Browse Topic: Failure analysis

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Overtake Safety Margin Formula Blind Spot Characterization Using a Micro Transformer with Monte Carlo Dropout Uncertainty and CARLA Validation2026-28-0141To be published on 11/05/2026
Overtaking another vehicle on a two-lane road can turn dangerous within a few seconds, especially when the gap to an oncoming vehicle is short or that vehicle is moving fast. Many driver-assistance systems rely on a simple, fast rule called the Overtake Safety Margin formula to decide whether an overtaking maneuver is safe, without running a full traffic simulation. This study checks the formula's reliability using a physics-based simulator that models three vehicles: the car overtaking, the car being overtaken, and the oncoming car. One million generated overtaking scenarios were evaluated using both the OSM formula and the kinematic simulator to identify cases where the formula classified a maneuver as SAFE while the simulator predicted an UNSAFE outcome. These mismatches, called blind spots, represented 3.98% of the evaluated scenarios and were concentrated in high oncoming-speed, short-gap situations, pointing to a specific weakness rather than random error. To catch these blind spots automatically, a small and efficient machine-learning model, a micro-transformer, was trained on the simulator's results. It reached 96.3% overall accuracy and correctly flagged 86.9% of the formula's blind spots, outperforming LightGBM, which detected 73.2%. The model's confidence scores were well calibrated, so they can be trusted to trigger an extra safety check when needed. An uncertainty-based search then used these confidence scores to find risky scenarios efficiently: 187 of the 500 most uncertain cases turned out to be unsafe, about 9.4 times more effective than random selection. Finally, the 30 highest-priority cases were replayed in the CARLA driving simulator, and 27 were confirmed to reproduce unsafe outcomes. Together, these results show that pairing a fast rule-based formula with a calibrated learning-based monitor can catch dangerous situations the formula alone would miss, supporting the safety documentation required for automotive safety-of-the-intended-functionality standards.
Sekaran, Nikhil, Sehgal, Vishal
Smart-ROPS — Machine Learning-Based Rear Occupant Protection System2026-28-0149To be published on 11/05/2026
Children dying in hot cars is not a new problem. Since 1998, more than 1,000 children have died this way in the United States alone — roughly 37 every year. That number has barely been reduced, which tells something alarming: the solutions built so far aren't solving it completely. Door-based reminders are a good example of why. They trigger when a rear door opens, but opening a door doesn't confirm a child was left behind. Single-sensor setups have their own gaps too; no single sensor handles every real-world scenario reliably on its own. Multi-sensor systems get closer, but most use rigid threshold-based rules that fall apart the moment conditions deviate — a sleeping infant barely moves, a child under a blanket reads completely differently on a thermal sensor. This paper proposes Smart-ROPS (Smart Rear Occupant Protection System), an embedded ML architecture that targets these specific failure modes without needing expensive hardware or complex software. Four sensor types feed the system: millimeter-wave radar, CO₂, thermal infrared, and ultrasonic. Data from these passes through three layers — the Perception Layer handles initial sensor fusion, the Processing Layer runs a decision tree as the primary classifier, and when confidence is low, a shallow neural network steps in for ambiguous cases. If a risk is confirmed, the Intervention Layer manages the response: starting with a smartphone alert and cabin ventilation, escalating to emergency services if needed. This is presented as an architectural design contribution — hardware prototyping and real-world testing are left for future work.
Shrimal, Harsh
Option for Introducing Vehicle Crashlytics with SOVD2026-28-0215To be published on 11/05/2026
Automotive E/E architecture is getting transition from distributed ECUs to high performing Zonal architectures. Traditional diagnostic methodologies based on Unified Diagnostic Services (UDS/ISO 14229) is being followed for providing failure analysis. It is difficult when debugging complex software and to find issues where lies exactly at modular level called “stack trace”. This could provide solutions for software bugs, failures or even container-level crashes in Software-Defined Vehicle (SDV). This paper provides a remote diagnostic framework that makes use of the ISO 17978 (SOVD) standard to visualize a “Vehicle-wide Crashlytics” as analogous to modern mobile application analytics with Firebase SDK. Also, the comparison of failure management with traditional diagnostic method to handling fault management in remote framework with both ISO 17978 (SOVD) and ISO 20077/20078 (Remote Diagnostic) is made. It also speaks how methodology can be formed for software logs capturing and traces execution triggered by function software level anomalies. Also, the constrains such as V2X bandwidth and data is monitored and controlled with Diagnostic Saliency Algorithm that helps to determine only relevant telemetry is transmitted via 5G or V2N. This framework proposal is checked with a simple application failure scenario, which leads to the reduction in “Mean Time to Repair” (MTTR) for software bugs. The reduction in MTTR is achieved since actionable root cause of software issue is shared directly from vehicle’s run-time environment. Future development of vehicle functions (SaaS) is expected to be integrated with SOVD and cloud-native observability patterns. This is much needed towards the scalable and quick development and deployment of applications into Vehicle as Digital Hub.
Kalirajan, Vignesh, Annamalai, Viswachandar, Balakrishnan, Arun Shankar
Multi-Objective Robust Optimization Method for CFRP Laminates Based on a Dual Dimensionality Reduction Strategy2026-99-234510/30/2026
This paper presents a robust multi-objective optimization method for a symmetric carbon fiber reinforced polymer laminate under uniaxial tension. The study focuses on the combined design problem of failure strength and failure displacement under material uncertainty. A fast structural response model is built by using classical laminate theory, and the Hashin failure criterion is used to predict the first-failure state of the laminate. The model takes uncertain material properties into account, so it can describe the effect of random changes in stiffness and strength on the structural response. To reduce the computational cost, the method uses a dual reduction strategy. The first step reduces the parameter space. Latin hypercube sampling is used to generate random samples, and Spearman correlation analysis is used to identify the key uncertain parameters. The second step reduces the sample space. K-means clustering is used to group the reduced samples and generate representative scenarios. Based on these scenarios, the study defines robust failure strength and robust failure displacement by combining the mean value and the standard deviation of the responses. A multi-objective genetic algorithm is then used to search for the Pareto solution set. After that, two single-objective optimizations are carried out to obtain the best strength and the best displacement, and these two values are used to form an ideal point. The two objectives are normalized, and the Pareto point with the smallest distance to the ideal point is selected as the final design. The results show that the proposed method can capture the positive relation between failure strength and failure displacement, identify the main uncertain parameters that control the response change, and provide a balanced design with good strength and displacement performance under uncertainty.
Wang, Yaoqiang
Modeling and Supervisory Reconfiguration of a Dissimilar Redundant Flight Control System under Common-Mode Failures2026-99-235810/30/2026
Common mode failures may simultaneously impair multiple redundant channels, threatening redundancy independence and flight safety. Existing studies have mainly focused on safety architecture analysis, analytical redundancy design, and reliability allocation, while systematic research on failure propagation in closed loop flight control systems remains limited. In particular, insufficient attention has been given to channel degradation divergence and unified modeling for online reconfiguration. To address these issues, a unified framework for common mode failure propagation is established. On this basis, a dissimilar redundant control architecture is constructed by combining a state feedback channel and a proportional integral derivative channel. A supervisory reconfiguration strategy is developed by integrating multi source degradation assessment, credibility based control allocation, and hysteresis based hybrid mode switching. Simulation results from a longitudinal closed loop model show that the proposed strategy captures the divergent degradation of heterogeneous channels and triggers coordinated reconfiguration during fault propagation. As degradation increases, the control system transitions from baseline operation to weighted fusion and then to a safety preserving degraded mode, with control authority shifted toward the more credible channel. Compared with the case without reconfiguration, the proposed method yields smoother control responses and improved tracking performance.
Peng, Cheng, Guo, Jianwei, Xu, Youping
Process and Performance Optimization Design of Metal-3D Braided Composite Joint Structures2026-99-234910/30/2026
The sleeve is the key assembly part of the high-speed internal electric spindle support of the high-precision CNC internal and external grinder, and its machining accuracy directly affects the running state of the spindle. The purpose of this study is to adjust the structural process to improve its bearing capacity in all directions. Combined with the refined mechanical simulation of 3D braided composites, the influence mechanism of joint thickness and surface pretreatment on the connection performance is studied from the aspects of stress distribution characteristics and damage failure mechanism. The overall performance analysis and design of the metal-composite sleeve are carried out. Experiments show that the thickness of the joint has a great influence on its bearing performance, and the effectiveness of the proposed pretreatment process is verified, which provides a reliable technical path for the realization of high-performance metal-3D braided composite connection structure.
Wang, Zijun, Chi, Xinfu, Li, Chengen, Li, Dinghua
Research on Failure Mode Verification of Civil Aircraft Based on Reliability Data2026-99-231410/30/2026
To verify the accuracy and completeness of FMEA and FTA, this paper proposes a comprehensive failure mode verification method based on reliability data. This method collects multi-source reliability data and identify actual failure modes occurring in equipment during operation firstly, thereby compiling a list of actual failure modes. Next, this list is compared with the FMEA report from the design phase to verify the failure modes themselves. A deeper qualitative verification of the causes, mechanisms, and impacts of the failures is then conducted, leading to the correction and updating of the FTA logical structure to ensure consistency between the safety analysis model and the actual failure logic.Building upon the qualitative verification, the method proceeds to quantitative verification. A comparative analysis is conducted between the actual failure rates of the failure modes and the estimated values in the FMEA. Using the validated failure rate data, the probability of the FTA top event is recalculated and compared against the safety target probability specified in airworthiness regulations to achieve quantitative verification of the failure condition probability. As a core innovation and enhancement of the method, this paper introduces sensitivity analysis. Through tools such as calculating Birnbaum importance and plotting tornado plots, it quantitatively assesses the sensitivity and impact of uncertainties in the failure rate parameters of each bottom event on the probability of failure condition, thereby identifying the key failure modes. The research findings provide theoretical support and a practical engineering foundation for evaluating the actual reliability level of the aircraft fleet, improving the accuracy of safety analysis during the design phase, and guiding preventive maintenance and design improvements.
Han, Bing, Li, Haiwei
High-Temperature Sealed Disc Spring Compression Load-Holding Performance Testing and Material Parameter Calibration2026-99-232210/30/2026
In high-temperature sealed assemblies, disc springs provide sustained preload to suppress leakage. However, at elevated temperatures, material creep and stress relaxation may reduce elastic recovery and accumulate permanent deformation, thereby degrading sealing reliability. Because the material properties of commercially procured disc springs vary with suppliers and production batches, they are difficult to apply directly in the analysis of high-temperature components. This study investigates Inconel-800 disc springs. Sustained compression tests were conducted at 600–900 °C to systematically obtain load–time responses and the temperature dependence of permanent deformation. The results show that, as temperature increases, the rate of force decay accelerates significantly and the residual load decreases markedly. At 800 °C and 900 °C, the permanent deformation approaches the compression limit, indicating that time-dependent material deformation becomes the dominant factor. Based on these results, a finite-element model consistent with the test conditions was established. Material creep parameters were calibrated from component-level compression data by minimizing the discrepancy between simulated and experimental curves. The identified parameters were validated under different temperature conditions and loading cases. The simulation results agree well overall with the experiments, and the errors remain within engineeringly acceptable limits. This study provides baseline data and an engineering method for obtaining material parameters to support material selection and structural optimization of high-temperature sealed disc springs.
Yang, Yuyao, Cai, Xianhui
Failure Tolerance of Male and Female Lower Extremities under Pure Bending and Combined Loading Modes09-14-03-001410/26/2026
Lower extremity injuries remain common in frontal motor vehicle crashes, with evidence suggesting increased vulnerability among female occupants. While prior research has established failure tolerances of midsize male lower extremities under bending and combined loading conditions, limited data exist for small female specimens. This study aimed to characterize and compare the failure tolerance of small female and midsize male postmortem human subject lower leg specimens under combined axial compression and posterior–anterior (PA) bending using consistent boundary conditions. Twenty-four lower leg specimens, including the tibia, fibula, and surrounding soft tissue, were obtained from 50th percentile male (n = 12) and 5th percentile female (n = 12) donors. Dynamic tests to failure were conducted at 1.5 m/s using a test apparatus designed to apply three-point bending in the PA direction with varying levels of superimposed axial compression (0, 2, 4, and 6 kN). When paired left and right legs from the same donor were available, they were assigned to different loading conditions to assess the influence of axial compression magnitude. Fracture timing was determined using force, strain, acoustic emission data, high-speed video, and post-test CT imaging. Results indicated that 18 specimens fractured at the tibial shaft, 5 near the potting interface, and 1 did not fracture. Under pure bending, mean failure moments were 255 ± 57 Nm for males and 156 ± 15 Nm for females. At 6 kN axial compression, failure moments decreased to 195 Nm and 72 Nm for male and female specimens, respectively. Among matched pairs, increasing axial load resulted in an average 21% reduction in bending moment at failure. These findings demonstrate reduced failure tolerance with increasing axial compression and highlight sex-based differences. The data provide a foundation for developing improved injury risk functions and scaling methodologies for diverse occupant populations as well as informing anthropometric test devices and human body models.
Carbon, Maria, Nazari, Isabella, Edinger, Timothy, Shin, Jeesoo, Hanggi, Connor, Kerrigan, Jason, Forman, Jason
LLM-Based Satellite Multimodal Knowledge Graph Construction: A Context-Aware Self-Interpretable Paradigm2026-99-290410/19/2026
This paper addresses three main bottlenecks in commercial aerospace multimodal data: semantic alignment difficulties, rigid ontologies, and context loss. We propose a method to construct satellite multimodal knowledge graphs (KGs) using Large Language Model (LLM).The process begins with layout analysis. This step preprocesses interleaved text-image satellite documents to align cross-modal semantics. To resolve ambiguity in technical terms, we developed a triple-positioning entity extraction mechanism. This mechanism directly identifies the original text, summaries, and entity types. For event nodes, we use an event-centric modeling paradigm. This paradigm captures spatio-temporal elements and other meta informations to ensure the nodes are self-interpretable. Entity normalization and automatic schema recognition rely on deep vector embedding. This embedding can semantic clustering the entities for the KG, eliminates the need for prior ontologies. We tested the method on real satellite datasets. The experimental results show high logical integrity and confirm its practical value for aerospace failure analysis.
Chen, Yanyu, Yu, Yeluo, Zhang, Jiliang, Bao, Junpeng
A Fuzzy Initiative-Yielding Mechanism for Space-Air-Ground Cooperative Communication2026-99-294110/19/2026
Space-Air-Ground Integrated Network (SAGIN) emerges as an appealing framework for implementing pervasive connections among diverse layers of space, air, and ground. The scheme relies on satellite deployment for extensive space coverage, Unmanned Aerial Vehicle (UAVs) acting as agile aerial relay stations, and ground robots for performing the final task assignment. Nevertheless, integrating heterogeneous nodes with varying mobility characteristics poses significant challenges: satellite operations are restricted by orbital dynamics, ground robot movements are restricted by topography constraints, whereas UAVs demonstrate flexibility and can establish line-of-sight connections with both satellites and ground robots. Current solutions usually adopt UAVs merely as passive relay nodes, causing inefficient adaptation mechanisms and excessive communication overhead when responding to dynamic perturbations or blocked connections. To overcome the aforementioned challenge, this paper proposes a novel fuzzy initiative-yielding coordination approach assigning two opposite behaviors. Initiative is assigned to UAVs in order to facilitate coordinated operations between layers, whereas Yielding refers to the adaptive response of satellites and ground robots. Contrary to previous research where behavioral assignments follow strict threshold rules, our fuzzy inference considers various parameters such as link quality, node state, and task priority, providing flexible behavioral assignments. Our predictive approach incorporates the Exponentially Weighted Moving Average (EWMA) technique to perform proactive failure avoidance. Based on five comprehensive experiments with 30 independent runs each, our approach obtains similar task completion rates (84.4%), but exhibits significantly lower communication overhead by up to 11 to 147 times compared to baseline methods. Furthermore, the proposed behavioral assignments avoid any coordination conflict (0 vs. 30.8), reduce completion time by 10.1%, maintain robust performance under 20% rule reduction, scale to 150-node mega-constellation scenarios, and exhibit higher fault tolerance under dynamic environments (81.5% vs. 79.8% of CBBA under high stress conditions).
Bao, Jie, Zhang, Yuping, Zhang, Ronghao
Optimal Low-Thrust GEO-to-DRO Transfers via a Multi-Layer Homotopy Strategy for Cislunar Applications2026-99-293710/19/2026
Low-thrust transfers from Geostationary Earth Orbit (GEO) to Distant Retrograde Orbit (DRO) are numerically difficult to compute because the underlying two-point boundary value problem is strongly affected by nonlinear cislunar dynamics, discontinuous control behavior, and the high sensitivity of indirect methods to the initial costates. Within the framework of the Earth-Moon Circular Restricted Three-Body Problem (CR3BP), this paper formulates an indirect optimal control model for GEO-to-DRO low-thrust trajectory design and develops a multi-layer homotopy strategy to improve the solvability of the problem. In the minimum-fuel formulation, the optimal throttle generally follows a bang-bang structure, which makes the associated shooting equations highly sensitive and often causes convergence failure. To reduce this difficulty, a smoothing homotopy is first introduced into the performance index, allowing the solution to evolve continuously from a minimum-energy problem with smoother control characteristics toward the target minimum-fuel problem. On this basis, a thrust continuation procedure is adopted to transfer the converged solution from an auxiliary high-thrust case to the desired low-thrust regime. However, when the conventional discrete continuation scheme becomes ineffective in a local thrust interval, a nonlinear intra-interval thrust homotopy combined with pseudo-arclength continuation is further employed to pass through the problematic region and maintain continuous tracking of the solution branch. Numerical results show that the proposed method can successfully overcome the local breakdown encountered in classical continuation and eventually obtain the minimum-fuel optimal transfer trajectory from GEO to DRO. The study indicates that the proposed framework enhances the robustness and continuity of indirect optimization for low-thrust transfers in the CR3BP, and it provides an effective computational approach for the design of cislunar transfer trajectories.
Liang, Jintang, Zhang, Zexu, Wang, Yiyu, Mao, Yicheng, Li, Yingshuo
An Electromagnetic-Thermal-Mechanical Coupling Model of the Three-Coil Wear Debris Sensors for Wide-Temperature and Kinematic Analysis2026-99-298510/19/2026
Real-time monitoring of metal wear debris in lubricating oil is crucial for accurately assessing aerospace equipment health and preventing catastrophic mechanical failures. Although three-coil differential inductive sensors are widely used due to their high sensitivity and robust structure, their detection performance inevitably degrades under the influence of multi-physics coupling effects inherent in complex industrial environments. Existing analytical models were primarily limited to single electromagnetic field simulations, failing to capture the intricate electromagnetic-thermal-mechanical interactions, which reduced analytical accuracy and hindered the optimization of sensor designs for extreme conditions. To overcome these challenges, this study established a comprehensive parametric simulation model to conduct a rigorous electromagnetic-thermal-mechanical coupled analysis of the differential sensor. Specifically, the research analyzed the underlying mechanisms by which wide temperature variations from -55 °C to 200 °C and specific debris kinematics exert varying degrees of influence on the induced voltage. Quantitative results indicated that both the isolated thermal and mechanical fields altered the voltage by a maximum of 0.649%, demonstrating that the sensor maintains a relatively stable response across extreme thermal gradients. Furthermore, the analysis revealed that increased debris velocity decreased the induced voltage amplitude due to the intensified motion-induced eddy current effects. Notably, in complex multiple debris scenarios, the strong dominant signals generated by ferromagnetic wear debris severely masked the weaker responses from non-ferromagnetic ones, indicating a substantial missed detection risk under mixed contamination conditions. Ultimately, this research successfully filled the critical simulation gap for evaluating these sensors under multi-physics coupling, providing robust theoretical guidance for their reliable deployment in complex industrial applications.
Shi, Xinfa, Duan, Chenhao, Zhen, Huanyi, Zhao, Yihe, Li, Min, Wang, Xiaozhang, Zhang, Qing, Li, Zhikang, Zhao, Libo
Acceleration Factor Derivation Using Test Bed and Field Failure Data of Automotive Engines2026-01-507710/19/2026
Reliability testing and validation are essential parts of any automobile development project. These tests mainly depend on two things: how much of the product’s target life is covered and whether enough samples are tested to capture variations. Today, most projects face tight timelines and cost constraints, which makes it important to design an optimized reliability test plan. Accelerated testing is widely used to reduce testing time, but finding the correct acceleration factor for a complex system like an automotive engine is difficult. Existing studies describe methods such as simple stress tests, step-stress tests, and degradation tests to shorten test duration. However, these methods need more samples at different stress levels to establish a clear relationship between stress and life and then calculate the acceleration factor. While such models work well at the component level, they become much more complicated at the system level because different components can have different acceleration behaviors. In this paper, a method is proposed to derive the acceleration factor by correlating engine test bed data with field failure and usage data. Test engineers often use standard accelerated test cycles for engines used in similar applications. As a result, organizations usually have historical test data and field data from earlier, similar products. The proposed approach models accelerated test data and field failure data separately and then links them to determine the acceleration factor. This derived factor can later be used in future engine development projects to convert test cycles into equivalent field mileage coverage. Weibull analysis and regression techniques are used to support the case studies presented in this work.
Koulage, Dasharath Baliram, Mondal, Kanchan
A Method for Evaluating System Robustness in Stochastic, High-Dimensional, Multi-Failure Mode Models2026-01-75289/22/2026
This paper introduces a method of predicting system robustness using engineering models with aleatory uncertainty. The Stochastic Robustness Evaluation and Categorization (SREC) method is useful for the design of systems where performance along some dimension is limited by several failure modes. SREC integrates and extends interaction plots and Monte Carlo methods to complex engineering models. These complex models are often difficult to evaluate and visualize due to the curse of dimensionality. SREC is effective for non-linear, non-convex, non-monotonic, and discontinuous models due to its basis in Monte Carlo methods. The method is based on the identification of low-performing solutions, the construction of probability density functions and intervals from these solutions, and the categorization of the input space based on the likelihood of low-performing solutions occurring. Using SREC in the late stages of the design process provides insight to the designer about possible improvements in the system’s robustness. A ground vehicle model based on a US Army test procedure is used to demonstrate the effectiveness of SREC on high-dimensional, multi-failure mode models.
Louis, Edward, Mocko, Gregory, Taylor, Evan
Physics-Constrained Procedural Generation of Synthetic Environments for the Robust Validation of Autonomous Maneuver and Logistics2026-01-75499/22/2026
The validation of Autonomous Ground Vehicles (AGVs) and intelligent logistics planners is frequently compromised by the ”Sim-to-Real” gap, where simulation environments fail to replicate the physical friction of operational deployment. Ideally, valid test cases must enforce strict mobility constraints and impose realistic sustainment penalties; however, many current generation tools rely on idealized terrain interactions and infinite-resource assumptions. We present a real-time procedural framework designed to generate high-friction validation environments that stress-test the robustness of the System Under Test (SUT). The architecture integrates gradient-based terrain analysis with a stochastic contested logistics model. It ingests synthetic heightmaps to precompute mobility corridors, ensuring that every generated evaluation episode adheres to vehicle-specific traversability limits. Simultaneously, a logistics kernel enforces fuel consumption scaled by terrain gradients and models supply chain interdiction as a parameterized Bernoulli process. We validate this framework through a ”Digital Twin” methodology, demonstrating that terrain-aware generation eliminates invalid initialization states (0% mobility violations) while the logistics model induces operationally relevant failure modes in the SUT. This unclassified, open-architecture approach supports DoD Verification, Validation, and Accreditation (VV&A) requirements by providing deterministic, reproducible edge cases for autonomous system evaluation.
Soykan, Bulent, Rabadi, Ghaith, Bochenek, Grace, Paul, Victor J.
Multimodal Digital-Twin Simulations for Off-Road Autonomous Vehicles2026-01-75509/22/2026
Research in autonomous driving has largely focused on structured, on-road environments in densely populated urban areas, leaving off-road autonomy comparatively underexplored despite its importance for applications such as search and rescue, agriculture, and defense. Progress in developing solutions for off-road autonomy is heavily constrained by the high cost, safety risks, and limited coverage of real-world off-road data collection, particularly for rare terrain-induced failure cases. To address these challenges, we introduce a large-scale simulation platform for off-road autonomous driving generated in the Unity3D engine. Our simulator provides indefinite data from multiple RGB cameras, LiDAR, GPS, and IMU sensors to support research in long-duration applications. Our platform also facilitates research in risk-aware planning through dynamic weather, lighting, and annotations for sequence-level failures like collisions and weather-induced sensor blockages. By combining long-duration temporal coverage, multimodal sensing, and procedurally generated terrain diversity, our simulator facilitates progress for systematic evaluation of learning-based autonomous driving models in unstructured, safety-critical environments.
Ross, Timothy, Boone, Julia, Afghah, Fatemeh
Efficient Integrated Reliability and Maintainability in a Digital Engineering Environment as Part of the Army Transformation Initiative2026-01-75319/22/2026
This paper presents an efficiently structured and integrated Reliability and Maintainability (R&M) process for implementation in a Digital Engineering (DE) environment during the product design phase, in support of the Army Transformation Initiative. This process links key R&M tasks to influence their execution and clarifies the relationship between a system's design risk and its R&M performance. The significant contributions of this process are: 1) establishing intra- and inter-task linkages for R&M activities within a comprehensive, systemic design process; 2) defining the direct impact on component and system-level R&M as a function of strategic design risk mitigation activities through a central Design Failure Modes and Effects Analysis (DFMEA); and 3) executing R&M tasks within a fully integrated, closed-loop R&M modeling and risk assessment approach, supported by a DE and AI-enabled environment.
Bieda, John, Gargrave, Jason, Damiani, Michael, Marlowe, Kasey, McGuinness, Sean
Intelligent Optimization Simulation Framework for Test and Evaluation of Autonomous Systems2026-01-75519/22/2026
This paper describes ongoing research and development of an efficient optimization/search–based modeling and simulation framework for rapidly identifying low-performance scenarios in advanced autonomous systems. Ensuring predictable, safe behavior across complex, integrated systems remains a core operational test-and-evaluation challenge. Our goal is to balance rigorous validation with timely deployment. We are developing TEAAS (Test & Evaluation of Advanced Autonomous Systems), a scalable, faster-than-real-time framework designed to uncover critical failure scenarios efficiently. Key features include GPU-accelerated parallel simulation and learning, computational intelligence–based search of optimal parameters, uncertainty quantification for reproducibility, and real-time physics-accurate sensor models. We conducted simulation experiments to evaluate and demonstrate the framework performance for two black-box ground-vehicle autonomous systems. Key results were that adequate uncertainty quantification can be achieved with as few as 10 repeated runs per simulation scenario, sensor realism has a significant effect on failure rate, distinct differences between the two autonomies failure modes were identified, and our efficient optimization/search methods identify critical performance regions in a small fraction of the number of simulations required by a naïve Monte Carlo search.
Snarski, S., Menozzi, A., Persons, B., Lazar, D., Khan, N.
Robust Fiber Optics for Ground Combat Vehicles: Unlocking the Bandwidth for the Mission2026-01-75419/22/2026
The U.S. Army’s Modular Open Systems Approach (MOSA) is driving data-centric vehicle architectures that demand higher bandwidth, faster decision loops, and greater cross-platform interoperability. Despite these needs, stakeholders hesitate to adopt fiber optics because of perceived fragility, field-retrofit FOD risk, and soldier-handling concerns. This paper characterizes common fiber failure modes in ground-vehicle environments and demonstrates how system-level ruggedization, connector design, and qualified components mitigate those risks. Drawing on demonstrated experience with hardened optics, connector-integrated transceivers, sealed media converters, and rugged cabling, we summarize practical architecture and field maintenance procedures that enable reliable fiber deployment in vehicles. Results show that, with appropriate component selection, installation practices, and built-in diagnostics, fiber optics can provide a robust, maintainable backbone for future ground vehicle networks.
Kouns, Heath, Simms, Marc, Weiss, Evan, Breedlove, Joe
Bridging Human Expertise and Machine Intelligence in Chassis System Teardown Evaluation2026-01-08059/14/2026
Teardown evaluation of chassis system components plays a critical role in benchmarking, failure analysis, and competitive product assessment. These inspections rely heavily on experienced engineers who interpret visual defect patterns, material conditions, wear signatures, and manufacturing variations. However, expert driven evaluation processes are often subjective, difficult to standardize, and challenging to scale across global engineering teams. This paper presents a structured AI-assisted expert evaluation framework developed to enhance consistency, preserve institutional knowledge, and enable continuous improvement in chassis component teardown analysis. The proposed system integrates convolutional neural network architectures, including ResNet18 and its variants, into a human in loop inspection workflow. AI models perform initial classification of component images (e.g., OK/not OK and defect subclasses) and provide associated confidence scores. These predictions are presented as decision support, while final authority remains with the evaluating expert. Experts can confirm or override AI outputs, annotate defect regions using bounding boxes, assign subclass categories, and provide structured technical comments. All expert interactions, including AI disagreements, are systematically recorded. Correction instances are analyzed to identify model limitations, ambiguous defect conditions, and data gaps. Expert validated evaluations are incorporated into the training dataset to enable iterative model refinement. This closed loop process supports progressive improvements in model robustness and classification accuracy across varying teardown conditions and component types. A centralized cloud-based repository maintains full traceability of inspections, including timestamps, AI confidence levels, expert modifications, and annotation metadata. This structured knowledge capture converts tacit engineering judgment into a persistent digital asset, supporting auditability, cross-site alignment, and accelerated onboarding of new engineers. The framework demonstrates how AI can be effectively deployed as an assistive technology in chassis teardown evaluation, improving repeatability, enhancing data driven benchmarking, and enabling scalable knowledge preservation without displacing expert authority.
Divakaruni, Saikiran, Vaibhav, Veer, Hansen, Scott, Hood, Trevor, Agrawal, Rahul
Safe State Definition and Verification for Distributed Multi-Controller EMB Architectures2026-01-08009/14/2026
The Electro-Mechanical Brake (EMB) system is an essential technology for safe braking in modern vehicles. However, the adoption of multi-controller architectures has introduced new challenges to conventional Safe State strategies. Traditionally, the Safe State defined in functional safety means "function shutdown," and in accordance with ISO 26262-1:2018 (Part 1: Vocabulary), aims for an "operational mode without risks exceeding reasonable levels." However, in the multi-controller architecture of EMB systems, the Fail-Operational Safe State concept is applied, where the system continues to provide limited functions even in the event of faults. It is essential to verify whether such operational modes actually satisfy the safety requirements of ISO 26262-3 and ISO 26262-4. This paper redefines the Safe State according to failure modes in EMB systems, analyzes system state transitions, and presents a coherence analysis methodology for validating the availability of resources required to provide limited functions in the Fail-Operational Safe State. Through this approach, potential design defects in multi-controller-based EMB systems can be detected early, validated across 1,149,952 fault scenarios with zero total-failure outcomes, and traceability of functional safety requirements can be established.
Kim, Kang San
Thermomechanical Fatigue Life Prediction of Grey Cast Iron Brake Rotors Using Advanced Material Models and Elastic-Plastic Fracture Mechanics2026-01-08169/14/2026
A unified thermomechanical fatigue (TMF) life-prediction methodology is presented for lamellar graphite (grey) cast iron brake rotors operating under the severe transient thermal loads that arise in brake dynamometer durability testing. The workflow links four ingredients within a single rotor-level framework: transient nonlinear finite-element analysis, temperature-dependent inelastic constitutive modeling, a mechanism-based short-crack TMF damage model, and an elastic-plastic (nonlinear) fracture-mechanics crack-growth simulation. Two constitutive descriptions are exercised for the structural analysis — the standard rate-dependent Chaboche viscoplastic model available in Abaqus, and a user material subroutine (UMAT) that couples Chaboche viscoplasticity with continuum damage in order to reproduce the tension–compression asymmetry of cast iron. The resulting stress, strain, and temperature histories drive a multiaxial thermomechanical fatigue Damage (DTMF) computation that estimates crack initiation and early extension, after which a nonlinear fracture-mechanics procedure simulates crack-front advance toward through-thickness failure. Both constitutive models correctly localize the crack-initiation site on the rotor inner diameter, consistent with the dynamometer observations; for the loading histories examined, the standard Chaboche model yields lives in closer agreement with test. The crack-growth simulation reproduces the rapid post-initiation propagation seen experimentally and resolves branch-wise differences in crack-front evolution through the rotor section.
Lee, Heewook, Garcia, Arnoldo, Liu, Yi, Hazime, Radwan, Boughanmi, Heni, Kassir, Abdallah
Numerical Calculation of The Ice-Breaking Resistance of the Icebreaker2026-99-15179/11/2026
This study investigates the governing characteristics of ice resistance encountered by icebreakers operating in multi-year ice regions, with particular emphasis on the effects of bow truncation length, vessel speed, and ice thickness. A numerical simulation framework was developed using the finite element platform LS-PrePost to reproduce ice bending, failure, and ship–ice interaction throughout the icebreaking process. The numerical predictions were subsequently validated against physical model test data. The results indicate that ice resistance exhibits an increasing trend as the bow truncation length, navigation speed, and ice thickness increase. The ice resistance of different bow truncation lengths in the multi-year ice area is different. By truncating the model ship at different positions from the bow and analyzing the ratio of the ice resistance of the truncated models to that of the full-scale model, researchers can better understand the effects of bow size. This can provide a theoretical basis for conducting ice resistance tests with truncated model ships in a limited-scale ice water tank, and has certain practical value for the design and optimization of the icebreaker’s hull lines.
Liu, Yanwei, Zhang, Xiufeng, Yu, Yingjie, Wang, Lucai, Zhao, Weihang
Numerical Investigation of In-Plane Antisymmetric Failure Modes and Load-Carrying Mechanisms of Steel Portal Piers2026-99-15949/11/2026
A nonlinear finite element model was applied to study the in-plane instability of steel portal piers, in which initial geometric imperfections, welding residual stresses, and material nonlinearity were considered. The modeling procedure was compared with experimental results from box-section members, and consistent tendencies in load level and deformation evolution were observed. In the numerical analyses, the initial elastic buckling configuration exhibited an in-plane antisymmetric form. As loading continued beyond the elastic range, this deformation pattern persisted. With further loading, the deformation remained purely axial while combining compression with bending. During this stage, plastic hinges appeared near the column tops, while lateral displacement became clearly observable. Comparison models with different geometric proportions show that variations in the span-to-height ratio and the beam–column stiffness ratio influence how instability develops and where plastic deformation tends to localize. From a design perspective, these trends can be considered when distinguishing instability characteristics and selecting stiffness proportions between beams and piers.
Li, Jie, Shangguan, Bing, Cheng, Zhangxu, Ruan, Furong, Bai, Fan
Research on Scalelike Adaptive Suction Flow for Wide-Speed Range Hypersonic Inlets2026-99-12529/4/2026
As critical components of aircraft, hypersonic inlets utilize shock wave compression effects to pressurize incoming flow. The interaction between shock waves and the boundary layer tends to generate separation zones, and it adversely affects inlet performance. As a method to significantly enhance inlet performance, suction technology can substantially reduce the size of separation zones when they form in the inlet. However, when the inlet is started and operating normally, suction configurations may cause mainstream leakage and make it difficult to meet the requirements of inlets with wider speed ranges. This paper designs an adaptive scaliform suction structure that utilizes a lift-generating design to induce a slight upward deflection of high-speed near-wall flow. It can reduce high-speed mainstream leakage without compromising the effectiveness in low-speed separation zones. Numerical simulations are employed to evaluate its suction performance in both inlet separation zone flow fields and supersonic mainstream flow fields. The internal flow mechanisms of the scaliform suction structure are investigated, and differences in its behavior across various suction flow fields, as well as its interference with the mainstream, are discussed. The study reveals that when the height of the scaliform suction structure is approximately 1/8 of the incoming flow’s velocity boundary layer height, the suction flow coefficient in the separation zone is twice that in the hypersonic mainstream. Furthermore, the loss in Mach number and total pressure recovery coefficient of the near-wall supersonic mainstream is controlled within 5%. This structure exhibits an adaptive suction capability for separation zones, thereby extending the starting speed range of the inlet.
Zhao, Xuening, Zhao, Yilong
A Method of Hamiltonian System for the Vibration Problem of Cracked Plates with Piecewise Boundaries2026-99-12599/4/2026
This paper focuses on analytical solutions for studying the vibrations of partially cracked orthotropic plates with piecewise boundaries using the symplectic elasticity method. Crack compliance coefficients are derived from the line spring model and introduced into the governing equations. In this paper, by establishing the Hamiltonian system and solving the Hamiltonian canonical equations, the vibration problem of cracked plates with piecewise boundaries can be reduced to finding the symplectic eigenvalues and symplectic eigensolutions. In the Hamiltonian system, the problem is transformed into seeking the solution of an algebraic equation system by the aid of symplectic eigensolutions and the adjoint symplectic orthogonal relations between the eigensolutions. Thus, for orthotropic plates with cracks under piecewise boundary conditions, this work presents a set of analytical solutions. Specifically, expressions for the free vibration behavior are derived. Furthermore, the steady-state response is determined. Finally, the transient dynamic response is also formulated and solved. The numerical results show that this method is effective and the natural frequency obtained in this paper is consistent with experimental results. A parametric investigation is performed, with the aim of comprehensively investigating the dynamic behavior of cracked plates subjected to piecewise boundaries. Significant findings include how aspect ratio, piecewise boundary conditions, and crack length affect structural vibration characteristics. For the plates containing cracks under piecewise boundaries, the frequency-response and the time-history curves for the forced vibration are plotted. These curves clearly illustrate the corresponding vibration characteristics of the plates. Some of the results can provide benchmarks for validating numerical or approximate methods. The method presented in this paper can provide a pathway for solving similar problems in the field.
Qu, Jianlong, Yu, Qinyu, Jia, Jufang, Xu, Xinsheng
Research and Analysis of Civil Aircraft Radio Altimeter Malfunction2026-99-12359/4/2026
The radio altimeter is an important navigation instrument on an aircraft, capable of accurately measuring the aircraft's true height above the ground or sea to ensure safe flight. This capability is crucial for ensuring normal flight operations, especially during critical phases such as takeoff, approach, and landing. Polar terrain is complex and continually changing. The vast, endless ice fields, crisscrossing glacier crevasses, towering icebergs, and weather conditions all add significant uncertainty to air travel. In such environments, the aircraft's navigation system is particularly important as a core device to ensure flight safety. This article provides a brief overview of the aircraft radio altimeter system. Using data and observations from production flight tests, it studies the specific challenges posed by radio altimeter failures encountered during these critical validation flights. The study synthesizes these findings and proposes a relatively general troubleshooting approach to address such issues. Furthermore, the effectiveness of this method has been rigorously validated through its application in solving a complex real-world radar altimeter failure case.
Song, Mingming, Mi, Yujie
Traffic-Load Fragility Assessment of Prestressed Concrete Hollow Slab Bridges Considering Load Characteristics2026-99-12999/4/2026
Assessing the vulnerability of bridges to traffic loads is critical for ensuring their long-term operational safety. The reliability of bridges under design vehicle loads or simulated random traffic flows constitutes the primary focus of existing research. Current research often lacks analysis that incorporates actual traffic load conditions. This paper proposes a traffic-load fragility assessment method for prestressed concrete hollow slab bridges considering load characteristics. The methodology integrates Metropolis-Hasting sampling algorithm with Copula functions to simulate random traffic flow, calculates resistance levels corresponding to structural cracking, yield, and failure states, and employs Monte Carlo sampling for failure probability calculation. Finally, a case study of four prestressed concrete hollow slab bridges is conducted to analyze their traffic load fragility. The results show that, under the same traffic load characteristics, different bridges have varying vulnerabilities corresponding to different failure states. The traffic-load fragility assessment approach put forward in this study can offer important technical support for both bridge design work and the development of vehicle load restriction policies.
Zhou, Yihang, Yang, Gan
Experiments on Effects of Self-Locking on Mechanical Response of Origami Metamaterials2026-99-12069/4/2026
Motivated by the negative Poisson’s ratio tetrahedral-trihedral polyhedron (TMP), this study systematically examines the role of self-locking mechanisms in determining the mechanical response and energy absorption capacity of rigid origami metamaterials. Quasi-static compression tests were conducted on specimens exhibiting three distinct geometries (B19, B22, B23) and four wall thicknesses (0.8–2.0 mm). The results of these tests revealed two unique self-locking behaviors. Type I self-locking originates from inter-wall interlocking, characterized by progressively decreasing inter-wall spacing during compression; Type II self-locking originates from interlocking between creases, characterized by creases contacting each other during compression. The fabrication of the specimens was accomplished through the utilization of FDM-based additive manufacturing, employing PEEK material. The results obtained from this study revealed two distinct locking behaviors: It has been demonstrated that type I locking enables sustained deformation without load reduction. In contrast, type II locking has been shown to result in premature collapse and diminished energy absorption capacity. The B22 configuration has been demonstrated to trigger both locking mechanisms concurrently, thereby significantly enhancing performance metrics. This has been evidenced by improvements in both crush force efficiency (CFE) and specific energy absorption (SEA), whilst also delaying densification. In contrast, structures dominated by a single locking mechanism exhibit premature failure (B19) or inefficient energy absorption (B23). These findings emphasize the pivotal role of synchronized self-locking activation and geometric configuration in enhancing impact resistance and energy dissipation, thereby establishing a foundational theoretical framework for the design of advanced metamaterials in protective engineering.
Wu, Baoji, Wang, Hairui, Jiang, Heng
Validation Study of the Jaguar Land Rover Aerodynamic Computational Fluid Dynamics Process Using Metric-Based Assessment Criteria2026-01-50729/3/2026
Credibility of simulation data has always been fundamental in aerodynamic vehicle development, as a significant amount of early design phase work is conducted virtually before a physical test property is made. As the automotive industry pivots toward artificial intelligence and machine learning techniques to assist in aerodynamic development, training these models with simulation data requires a comprehensive understanding of the accuracy and validity of the underlying simulation. It is critical these systems are trained from reliable data with a full understanding of both the limitations and predictive performance of the computational fluid dynamics (CFD) process and the wind tunnel facility it is benchmarked against. Validation and verification studies have been a long-established set of guidelines to determine if the simulation model appropriately reflects reality (validation) or if it has been set with robust numerical schemes, mesh settings, or boundary conditions (verification). The work presented here shows a comprehensive validation study with more than 400 test configurations and 18 vehicle properties. It evaluates Reynolds-averaged Navier–Stokes (RANS) and detached eddy simulation (DES) approaches using moving reference frame (MRF) and rigid body motion (RBM) to account for wheel rotation and comparing STAR-CCM+ CFD process and the FKFS Aeroacoustic Wind Tunnel (AAWT). The results demonstrate that DES—particularly when wheel rotation is modeled using RBM—provides the highest overall predictive performance, with a drag accuracy from −2% to +4% for 80% of cases with corrections applied, which gets to ±2% for over 95% cases with an additional calibration step. A metric-based assessment criterion that combines key performance metrics into a single detection event (DE) score derived from failure mode effects analysis (FMEA) principles is proposed with an example shown for the 2021 Range Rover Velar. The benefit being that it removes a more judgement-based, qualitative approach, aiding toolset selection and methods development gaps.
Beves, Christopher, Simmonds, Nicholas, Dalmau Graells, Eric
DESIGNING OUT corrosion at the wheel26AUTP09_049/1/2026
The case for advanced powder coatings. Corrosion in automotive components is often framed as a cost problem, but for design and manufacturing engineers it is more accurately understood as a system-level failure mechanism. Nowhere is this more visible than in wheel assemblies, where environmental exposure, mechanical damage, and coating performance intersect. For wheel manufacturers, corrosion is not simply a maintenance concern; it is a function of material selection, geometry, surface preparation, and coating system design, all interacting under real-world conditions. The global cost of corrosion is frequently cited in trillions of dollars annually. Estimates from the Association for Materials Protection and Performance (AMPP) place this figure at over $3 trillion, with up to 35% considered preventable through improved design, material selection, and protective strategies. For engineers, the more relevant point is that a significant proportion of corrosion-related failure can be addressed through earlier-stage decisions. In practice, this means designing components and processes that limit the initiation and propagation of corrosion, rather than relying on coatings as a final barrier alone.
Carvalho, Gustavo
High-temperature JOINT RELIABILITY26AUTP09_039/1/2026
Why preload retention matters more than fastener grade. In exhaust and thermal management applications, joint failures are frequently attributed to fastener fracture or rotation-driven loosening. In practice, many joints in these systems fail through a different mechanism entirely: gradual preload loss that occurs without fracture, without visible nut rotation, and without any indication during installation or room-temperature inspection that the joint is degrading. Understanding this distinction is becoming more important as exhaust system temperatures increase, assemblies get lighter, and vibration environments remain demanding. The gap between what a room-temperature validation protocol confirms and what a joint actually experiences in service has widened considerably in recent years, and conventional fastener selection methods have not kept pace.
Kapa, Kyle
Simulation of Gas Diffusion in Nanoscale Microchannels at the Parallel Seam-Weld Interface2026-99-04198/28/2026
Driven by the stringent service conditions of aviation, aerospace, and military equipment, parallel seam welding, as an advanced resistance-welding packaging process, has been widely applied in ceramic-metal packages that require high hermeticity, owing to its excellent sealing performance and reliability. In this study, targeting the hermeticity failures that appear in parallel seam-welded ceramic packages after temperature cycling, molecular dynamics simulation is used to systematically investigate helium diffusion in nanoscale interfacial microchannels and its effect on hermeticity. On the LAMMPS platform, a three-region model is constructed that includes a helium-charging region, a wall-channel region composed of Fe, Ni, and Au, and a vacuum leak region. The Lennard-Jones potential is used to describe interatomic interactions, and a thermal-cycling environment conforming to MIL-STD-883, with a temperature range from -50°C to +125°C, is simulated to represent actual service conditions. The simulation results show that when the channel diameter is less than or equal to 1.2 nanometers, the number of leaked helium atoms remains constant at approximately 22 and is not affected by temperature; when the diameter is greater than or equal to 1.6 nanometers, the leakage exhibits significant temperature dependence. For example, in a 2.6-nanometer channel, 212 atoms leak at 423 K and 176 atoms at 223 K. Both leakage flux and leak rate increase markedly with channel size. OVITO analysis confirms that helium diffusion exhibits molecular-flow characteristics; at very small apertures, atomic escape efficiency is limited by the frequency of collisions with the wall. These findings provide insight for improving hermetic packaging and reliability of critical electronics used in aviation, aerospace, and military equipment.
Li, Xiangyang, Gong, Yubing, Zheng, Xianling
Stress Analysis and Simulation Study of Propane Spherical Tanks2026-99-03348/14/2026
As special pressure-bearing vessels, spherical tanks are widely used in chemical, oil refining, and other fields. However, their safe operation faces the dual challenges of structural failure and leakage diffusion. Meanwhile, due to its low lower explosive limit and the low ignition energy required, propane will evaporate rapidly after leakage to form an explosive mixed gas, which may further trigger severe accidents such as combustion and explosion. Therefore, this paper takes a 3000 m3 propane spherical tank as the research object, comprehensively applies the finite element analysis method, and systematically researches stress distribution, aiming to provide theoretical support for the safety design of spherical tanks and accident prevention and control.
Huang, Yuanxuan, Tao, Gang, Zhang, Lijing
Reliability Calculation and Analysis of Influencing Factors for Girth Welds in High-Grade Steel Pipelines Based on HMC-SS2026-99-03428/14/2026
Fracture failure of girth welds in high-grade steel pipelines poses a critical threat to pipeline integrity. Leveraging enhanced digitalization in pipeline engineering, a statistical database has been developed to support reliability analysis based on actual operational data. This study utilizes real project data to analyze the failure probability and key influencing factors of girth welds containing crack defects, thereby providing theoretical support for safety design and risk management. To overcome the conservatism of traditional deterministic methods, a probabilistic reliability model was established, incorporating a modified PRCI-CRES ultimate tensile strain criterion. Addressing the inefficiency of standard Monte Carlo (MC) simulation in high-dimensional low-probability contexts, an efficient Hamiltonian Monte Carlo-Subset Simulation (HMC-SS) strategy was introduced. Results show that HMC-SS improves computational efficiency by 99.95% over MC, with only 0.90% relative error. Key findings include: crack depth has the strongest influence – variation from 0.92 mm to 3.68 mm, which increases failure probability by 103 times; the strength matching coefficient is dominant, and higher values reduce failure risk; strain demand exhibits a positive correlation with failure probability and couples with material properties. It is concluded that high- or equal-strength material matching should be emphasized in welding, and reliability-informed design should account for multi-parameter interactions to ensure global safety.
Yang, Kai, Wang, Kaihong, Wang, Bin, Shao, Jia, Yu, Weichao, Zhang, Dong
Anti-splash System of Sprinkler Based on Millimeter Wave Radar and Machine Vision Fusion2026-99-03238/14/2026
In view of the problems that it is difficult to accurately control the spraying area of the mining sprinkler, and the resource waste caused by the mis-spraying material stacking area, as well as the failure of traditional radar monitoring in the complex electromagnetic environment, this paper proposes an anti-splashing system for the mining sprinkler. By combining millimeter wave radar and visual recognition fusion technology, the overall scheme of the anti-splash system is proposed. Then the control simulation of the whole system is carried out. The results show that the problem of poor control in traditional sprinkler operation can be effectively solved, and the sprinkler area can be adjusted intelligently. Finally, in order to verify the accuracy of the algorithm used in this paper, different algorithms are used for comparative experimental verification. The results show that the Modified YOLOv4 algorithm has a high accuracy of 98.75 %, which has good applicability and provides a theoretical basis for subsequent research.
Hou, Lin
Design of Adaptive Overtorsion Sliding Mode Observer Based on Logarithmic Gain Law and Estimation of Satellite Disturbance Torque2026-99-03158/14/2026
The vigorous rate of new spacecraft being launched has made the accurate estimation of in-orbit environmental disturbances torques paramount to reducing attitude control performance corrosion. Leveraging telemetry from an asset in low-earth-orbit, we present a novel Adaptive Super-Twisting Sliding-Mode Observer, which interlinks three techniques heretofore decoupled: 1) saturation-constrained angular-acceleration adaptation; 2) Kalman-filter preconditioning of angular velocity; and 3) state-weighted logarithmic gain with dual leakage. Denoising of raw Euler angle sequences and detection of quasi-steady epochs are achieved with a customized Kalman update, while an adaptive band-pass stage isolates the torque-related acceleration signature. Casting these filtered data into the super-twisting form, we update the log gain on-the-fly, and twin leakage terms remove excess energy with accompanying chatter rejection—without compromising bandwidth. Head-to-head telemetry tests show a positive margin headroom on noise attenuation that has to be compared with the power-gain type counterpart and that increases with the signal roughness, thereby validating the fact that this technique refines environment torque estimates and hence strengthens robustness design envelopes in next-generation attitude-control systems.
Yin, Xu, Deng, Yuhui, Chi, Dongxiang
Design of a Four-Wheel Turning Tobacco Harvester Suitable for Hilly Areas2026-99-03338/14/2026
To address the core requirement of “layered ripeness and non-destructive harvesting” in tobacco-growing hilly regions of China, a specialized tobacco leaf harvester was developed. Considering the challenges posed by scattered plots and complex terrain, a four-wheel steering chassis system was proposed. The platform adopts a four-wheel independent drive and steering (4WID-4WIS) configuration, powered by DC servo motors and integrated with a microcontroller-based ROS system. The resulting drive chain—comprising motors, gear reducers, and off-road tires—achieves a maximum operating speed of 0.5 m/s. A novel rotary cross-blade harvesting module was designed in conjunction with a conveyor-based transmission mechanism, enabling stratified harvesting and leaf transport. Full-condition field tests were conducted. In terms of mobility, the harvester achieved stable operation at 0.5 m/s on cement roads, 0.1–0.2 m/s in fields, and demonstrated slip-free climbing on 20° slopes. In terms of harvesting performance, the system’s adjustable modules accommodated varying plant heights; however, issues with blade grip were observed when handling irregularly slanted stalks, affecting collection efficiency. During continuous field entry and exit operations, no mechanical failures occurred, verifying the prototype’s operational stability. This study introduces an innovative combination of omnidirectional mobile chassis and stratified blade modules, offering technical support for the modernization of tobacco agriculture. Further refinement of the harvesting strategy will be pursued to enhance practicality.
Guo, Ting, Gu, Jin, Li, Wen, Tang, Xiaoming, Long, Chao, Yang, Dongchao
Failure Analysis of the Safety Valve Spring in a Dangerous Goods Tanker2026-99-03138/14/2026
During the operation, a spring in the built-in safety valve of a dangerous goods tanker. A comprehensive failure analysis of the material was conducted through macroscopic and microscopic inspections, metallographic analysis, energy spectrum analysis (EDS), and hardness tests. The failure mode of the broken spring was brittle fracture. The fracture morphology was like that of ice sugar, and the chemical composition of the spring steel met the specified requirements. The main cause of fracture failure is the mechanical damage to the inner surface during the spring manufacturing process, which leads to stress concentration in the damaged area and ultimately results in fracture. In addition, manufacturers should strengthen and standardize the production process to prevent mechanical damage and select high-purity spring steel to improve the durability of the springs.
Yang, Lijun, Li, Qingshan, Xiong, Mingming, Liu, Mingming, Wu, Junyao, Yu, Lang, Zhang, Zewei, Xie, Xumeng
Research on the Cumulative Damage Mechanism of Special Equipment Steel Structures Based on Complex Load2026-99-10118/7/2026
Steel structures subjected to complex loading conditions undergo various types of damage, including fatigue, crack propagation, plastic deformation, and corrosion. As time and loads accumulate, these damages may lead to structural failure. The investigation of the damage mechanisms and constitutive models for special equipment steel structures under complex loading has been a significant challenge in engineering. This study develops a constitutive model for steel structure damage under static and dynamic loads, as well as vibration disturbances, through a normalization approach. The proposed model is validated via simulation to assess its feasibility. The findings offer a theoretical foundation for the design, life prediction, and health monitoring of steel structures in special equipment, aiming to enhance their safety and reliability. This research provides critical insights into damage analysis, failure prediction, and the optimization of repair strategies for steel structures, with significant practical implications in engineering applications.
Wang, Jun, Yu, Zhen, Huang, Yong-qiang, Chen, Wei-bi
Research on Corrosion and Friction Behaviors of 8Cr4Mo4V Bearing Steels in Corrosive Medium Environments2026-99-10068/7/2026
Corrosion-wear damage behavior affects the bearing life and reliability seriously in a corrosive environment. The accurate evaluation of the tribocorrosion behavior of 8Cr4Mo4V bearing steel samples is critical for the application and protection of bearings. The present work seeks to establish the relationship between laboratory salt spray accelerated experiments and the corrosion of 8Cr4Mo4V steel samples in real outdoor marine atmosphere exposure, and investigate the tribological behavior in the corrosion-wear process under artificial seawater. Results show that salt spray corrosion tests can well simulate the corrosion of 8Cr4Mo4V steels in marine atmospheric exposure. The tribocorrosion performance of 8Cr4Mo4V steels under artificial seawater conditions is affected by the temperature effect of the corrosive liquid and the working conditions. Increased normal load and reduced rotational speed can improve the anti-friction performance. This work offers the possibility and reference of precise control of corrosion-wear-coupled damage failures for bearings.
Zhao, Chao, Ying, Lixia, Nie, Chongyang, Zhu, Tianlin, Sun, Dong
683 Guidance for Electronic Shop Reports in Aviation MaintenanceARINC683 (Current)8/4/2026
The purpose of this standard is to provide guidance for the content, format and two-way electronic exchange of data between a Service Provider and the Customer. The standard is focused on the production of an electronic Shop Findings Report by the Service Provider, and to promote automated electronic data exchange.
Aviation Maintenance Committee
Why your bearing isn't enough: A guide to designing a maintenance-free pivot26TOFHP08_068/1/2026
Engineers designing pivot points for outdoor and heavy-duty equipment have long accepted the familiar routine: grease it, run it, regrease it and repeat. This approach may work well enough. But as equipment pushes into harsher environments and tighter service windows, “well enough” is no longer the standard. Maintenance-free pivots - pivots that run dry, resist corrosion and hold their tolerances through seasons of hard use - offer an increasingly compelling alternative. Designing one requires rethinking what a pivot point actually is, with most engineers focusing only on the bearing itself. While this instinct is understandable, it's also incomplete. A pivot consists of a bearing, shaft and housing working together, requiring a systems-level approach. Optimize only one element and you may still end up with a failure.
Prokopec, John
Analysis of Leakage Causes of 6ADG011VR Branch Pipe in a Power Plant2026-99-02317/31/2026
The socket-welded branch pipes of a power plant leaked and failed in the ADG System. To find the cause of the failure, this paper analyzed the failure reasons of the socket-welded branch pipes through macroscopic inspection, chemical composition analysis, mechanical performance test, metallographic inspection, and fracture microscopic analysis. The results show that the failure mode leading to leakage in socket-welded pipelines is fatigue cracking, which initiated at the weld toe on the outer wall and propagated inward. The vibration generated by the system environment is the main cause of fatigue cracking of socket-welded branch pipes.
Zhu, Jinhui
Effects of Arrangement Patterns on Static Stability and Leakage Characteristics in Hybrid Labyrinth-Honeycomb Seals2026-99-01667/31/2026
In this work, three-dimensional models of axial hole labyrinth-honeycomb seals (AHLHS) and circumferential hole labyrinth-honeycomb seals (CHLHS) were established by CFD to investigate the influence of different arrangement patterns on the static stability and leakage characteristics of two seals under choked and unchoked flow conditions and various eccentricities with different values. The results show that the two configurations have different advantageous ranges, and the hole arrangement pattern will not significantly change the pressure difference distribution between the two seals. Under most studied conditions, AHLHS maintains lower absolute values of stiffness coefficients, pressure difference groove, and negative cross-coupled stiffness coefficients, resulting in higher stability.
Li, Qing’an, Gao, Tongxin, Li, Zeze, Pang, Shuai, Lü, Yanjun, Zhang, Yongfang
Research on Fault-Tolerant Control Strategy for Drive System Failure of Corner Module-by-Wire Chassis Vehicles2026-01-50547/31/2026
As an emerging research focus, corner module-by-wire chassis vehicles overcome the limitations of traditional chassis in flexibility, cost, and development efficiency, serving as a key infrastructure in the autonomous driving era. However, their numerous actuators raise significant actuator failure risks. This paper analyzes the characteristics of such vehicles and studies fault-tolerant control for drive system failures. Firstly, a vehicle model for the corner module-by-wire chassis was established based on CarSim and Simulink. Then, a hierarchical lateral stability control strategy was designed for the non-faulty actuators: the decision control layer employed sliding mode control (SMC) and fuzzy PID control, selecting the optimal method to output additional yaw moments; the control allocation layer distributed the upper-level target yaw moments based on the vertical load of the tires, converting them into individual wheel torques to meet the constraints. For the drive system, potential fault scenarios were analyzed and their fault modes were classified. By using the non-faulty actuators for torque reconstruction, fault-tolerant strategies were designed for single-motor, diagonal dual-motor, and coaxial dual-motor faults. A co-simulation platform was built using MATLAB/Simulink and CarSim, testing the stability control strategies under three fault modes in constant-speed straight-line and double-lane change conditions. Simulation results show that the designed drive system fault-tolerant control strategy effectively maintains the vehicle’s expected dynamic performance and stability.
Zheng, Hongyu, Zhang, Tianhao, Zhang, Yuzhou
Reliability Evaluation of Five-Axis Machining Center based on Improved FAHPEWM-Extension Theory2026-99-01027/31/2026
To address the challenge of accurately assessing the reliability of complex equipment, a reliability evaluation system for a five-axis machining center was developed based on extension theory. By collecting and analyzing the failure modes and data of various subsystems, the strengths of the Fuzzy Analytic Hierarchy Process (FAHP) and the Entropy Weight Method (EWM) were combined to determine the weight of reliability evaluation indicators for both the machining center and its subsystems. A comprehensive assessment of the five-axis machining center's overall reliability was conducted. According to the principle of maximum membership, the reliability grades for the spindle system and the feed system were both rated as “excellent.”
Fei, Shouxiang, Wang, Dechao, Piao, Chengdao, Zheng, Shengkui
Research on Failure Analysis of Aircraft Windshield Outer Layer Fracture Caused by Arc Fault2026-99-01287/31/2026
The malfunction of the aircraft windshield electric heating system, particularly arc discharge, poses a serious threat to flight safety by causing glass breakage. A systematic study was conducted on the causes and effects of arc faults on windshield structural integrity, employing macroscopic observation, microscopic analysis, and energy dispersive spectroscopy (EDS) following a windshield fracture incident. The results indicate that arc discharge typically occurs at the interface between the heating film busbar and adjacent structures. Localized high temperatures cause the outer glass to fracture, generating radial cracks. The ablation of the busbar silver coating and the carbonization of the PVB interlayer are direct evidence of arc action, whereas the heating wire remains a passive component affected by the high-temperature environment. The fault is primarily attributed to local disbonding at the busbar interface and moisture ingress. Based on the findings, recommendations are proposed for process optimization and inspection method improvement, providing a basis for the safe design and maintenance of windshield structures.
Chen, Li, Feng, Yanpeng, Ding, Keqin
Engineering Practice of Sealing Design and Testing Technology for the Solar Array Drive Assembly of Tianhe Core Module2026-99-02437/31/2026
The Core Module of the space station is the first module of China’s Space Station, responsible for controlling the key parameters such as orbit, speed, and pressure of the entire space station, and serving as the control center of the assembly. The Solar Array Drive Assembly is a part of the Core Module. It needs to participate in the functional requirements of the whole cabin sealing of the cabin body, so it adopts the design scheme of semi-sealed. By adjusting the compression ratio and volume fraction of the sealing ring, and the roughness of the sealing surface, the overall sealing performance is improved. A small cavity leak detection hole is added to realize the sealing effect of detecting the second-layer seal separately. The real leakage rate of the drive mechanism is detected effectively by using multiple calibration schemes in the leak detection process, and the semi-sealing technology of the Solar Array Drive Assembly is verified, which has guidance and reference significance for the subsequent spacecraft design requiring a sealing function.
Dai, Fei, Zhu, Jiahao, Huang, Mengzhe, Qian, Zhiyuan
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