Browse Topic: Failure analysis

Items (2,954)
Find
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
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
Research on Identification of Key Geometric Errors in Five-Axis Machine Tools Based on Global Sensitivity Analysis2026-99-01597/31/2026
The geometric error (GE) accounts for a significant factor affecting the machine tool’s machining accuracy, and in most cases, large GEs will result in a substantial deviation from the required shape of the machined workpiece. GEs are often observed in five-axis machine tools, and identifying and measuring these errors turns out to be challenging. In the present work, we proposed a novel GE identification approach based on simulations and tests conducted on a BC-type dual-rotary five-axis machine tool. Specifically, a machine tool volumetric error model (VEM), incorporating 41 GEs (the complete model), was constructed using the homogeneous coordinate transformation approach. Then, Sobol sensitivity analysis in conjunction with quasi-Monte Carlo estimation was introduced to the VEM to measure how much each GE contributed to the total volumetric error. The subsequent analysis identified 21 key geometric errors (KGEs). We also compared the simplified VEM and the complete model, and it was revealed that there was little difference between the two, which confirmed the effectiveness of our method. The present work is intended to provide a reference for simplifying VEMs, error element identification, and error compensation.
Zhang, Jinlong, Shi, Zhaoyao, Yang, Hongtao
Modelling Failure Propagation in Material-Driven Collaborative Manufacturing Networks Using Cellular Automata2026-99-01207/31/2026
Collaborative manufacturing networks enhance production efficiency but are increasingly vulnerable to cascading failures due to their complex interdependencies, particularly in critical processes like gear manufacturing. This study addresses this challenge by proposing a dynamic modelling framework based on Cellular Automata. Utilizing manufacturing resource and task scheduling data, a material flow-driven Directed Acyclic Graph (DAG) is constructed to capture the network’s hierarchical topology. Key innovations include state transition rules with memory effects, where dynamic failure probability integrates neighbouring node states and historical failure records, governing normal node failure, recovery, and re-failure (with an attenuation factor reflecting enhanced resilience). The case study focusing on the gear manufacturing industry, through simulations on a 100-node gear production network, reveals spatiotemporal failure propagation patterns. By implementing resource redundancy configuration and material flow optimization, iterations generally converge around 35 steps, demonstrating significant self-recovery potential and strong network robustness in collaborative manufacturing networks. This approach provides a scientifically grounded tool for identifying cascading risks in collaborative manufacturing networks.
Bai, Hao, Kou, Zhida, Liang, Jingya, Zhang, Cheng
Advancing Reliability Centered Maintenance: A Robust Statistical Approach for MTBF Estimation in Aero-Engine Fleets via Subgrouping Strategy and Dual Weibull Modeling2026-99-02137/31/2026
Fleet heterogeneity, from manufacturing variations and diverse operating conditions, complicates reliability analysis by obscuring true failure patterns in aero-engines. This is a critical challenge in an industry as inaccurate Mean Time Between Failures (MTBF) estimates threaten safety and inflate operational costs, by forcing a choice between inefficiently conservative maintenance or the risk of in-service failures. Conventional analysis often fails by pooling all fleet data. To address this, our paper presents an analytical framework that improves predictive accuracy by filtering, rather than aggregating statistical noise. The methodology uses a Randomized Block Design (RBD) and ANOVA hypothesis test to screen a diverse dataset and isolate statistically homogeneous subgroups. This filtration identifies a core fleet with a consistent failure signature, providing a purified dataset for modeling. This refined data is then modeled using both Weibull and the Exponentiated Inverse Weibull distributions to ensure the results are robust and not model-dependent. Applying this framework to a 25-engine dataset that experienced 66 failures, we isolated a stable failure pattern, yielding a primary MTBF of 171.16 hours and a cross-validated MTBF of 176.35 hours. The close 3% convergence between these models validates our approach. By providing a dependable MTBF, this work establishes a stronger foundation for data-driven Reliability Centered Maintenance (RCM). It empowers maintenance planners to move toward evidence-based intervals, safely extending engine time-on-wing, optimizing spare parts inventory, and significantly reducing direct operational costs for airlines.
Jubaid, Mayin Uddin, Bebe, Gibson, Bigyen, Musa Pethuel, Anik, S M Kullul Mehedee, Yasmin, Ashrafi, Sahran, Mohamed Sideek Mohamed
Analytical Analysis of Wellbore Stresses under Fluid Pressure and In-Situ Stress in Three-Dimensional Wellbores2026-99-08317/30/2026
During fluid injection operations such as fracturing and well killing, the casing, cement sheath, and borehole wall rock are subjected to three-dimensional in-situ stresses and internal pressure. If the equivalent stress exceeds the material’s yield strength, component failure may occur, leading to wellbore failure or even blowout accidents. In order to investigate the stress distribution in wellbores under specific working conditions, a three-dimensional mechanical model of curved wellbores was established. By adopting the superposition principle and stress function method, the influence of horizontal in-situ stress non-uniformity on the fourth equivalent stress of various components was analyzed. The study demonstrates that under three-dimensional in-situ stress, the fourth equivalent stress of each component increases with the rise of horizontal in-situ stress load non-uniformity and azimuth angle. Meanwhile, borehole azimuth angle and in-situ stress load non-uniformity exert a greater influence on the fourth equivalent stress of the casing, while internal pressure has a lesser impact on it. The effects of azimuth angle, horizontal in-situ stress load non-uniformity, and internal pressure on the fourth equivalent stress of the casing are more significant than those on the cement sheath and borehole wall rock. The research results can provide theoretical and technical references for wellbore design and safety improvement, as well as for the structural safety assessment of components such as automotive chassis and body frames under complex dynamic loads.
Zhang, Wenzhe, Jiang, Wu, Guo, Ziwang, Cao, Yinping, Dou, Yihua
Research on the Structural Performance of a New Modular Fireproof Wall for Converter Station Valve Hall in High-Altitude Areas2026-99-08327/30/2026
Aligned with the “3060 dual carbon” goal, the rapid growth of new energy installation capacity in China’s western high-altitude regions has caused an urgent demand for UHV converter station construction. This paper suggests a prefabricated structural system by using embedded ear-shaped tongue-and-groove UHPC wall-column connections to meet the challenges of traditional cast-in-place concrete firewalls, such as prolonged construction periods and difficulty in quality control in harsh environments. The seismic performance of the connection was investigated through pseudo-static tests and finite element analysis. The results show that failure mainly occurs on the wall–column interface, with cracks mainly appearing at the wall panel corners. The scaled model demonstrated full hysteresis loops, indicating stable energy dissipation. The ear-shaped tongue-and-groove connection showed superior initial stiffness and ultimate load-bearing capacity (404.3 kN) compared with the straight-type connection (177.5 kN). An increase in the semicircular diameter improved load capacity, while the axial compression ratio had little effect. This study proposes a theoretical reference for the design and application of prefabricated valve hall structures in high-altitude regions.
Wang, Fengyun, Yan, Yong, Zeng, Cheng, Zhou, Ting, Ren, Zhaoyang
Research on Multi-Physical Field Accelerated Life Test for Long-Life Rotary Mechanism for Space Applications2026-99-08147/30/2026
The coupled multi-physical field environment in space, including vacuum, high-low temperature cycles, and temperature gradients, is the key factor affecting the life of the spacecraft’s rotary mechanism. Aiming at the use requirements of long-life space rotary mechanisms, this paper designs a multi-physical field accelerated life test scheme. This scheme simulates the vacuum environment, high-low temperature cycles, and temperature gradient conditions encountered during on-orbit operation. Ground-based accelerated life tests were conducted based on this scheme to verify the life of the mechanism under a comprehensive environment. Taking a certain type of space rotary mechanism as the test object, an integrated test platform was constructed, incorporating a vacuum simulation system, a temperature gradient control system, and a mechanism performance test system. Corresponding test procedures and failure criteria were established. Test results verified that after accumulating 130,000 ±7° small-angle reciprocating swings, the mechanism’s lifespan indicators met expectations. Post-test, the overall performance of the mechanism still satisfied the design requirements, with key moving components remaining in good condition. This study provides important experimental evidence for the on-orbit application of this mechanism type and offers valuable engineering reference for the design and evaluation of life tests for space mechanisms under multi-physical field coupling conditions.
Wang, Haomiao, Du, Yuefei, Huang, Mengzhe, Yang, Jinping
Analysis of the Cause of Knocking Noise in a Marine Dual-Power Dual-Branch Transmission Gear System2026-99-16507/24/2026
This study investigates the knocking noise phenomenon in a marine dual-power dual-branch transmission gear system. Vibration mechanisms are analyzed, and potential failure modes are assessed. System vibration data were evaluated using time-domain and frequency-domain methods. Results show that overall vibration levels remained within acceptable limits, with no indication of imminent failure. Physical inspection confirmed that the shaft, gears, bearings, housing, and installation met specifications, with no observed performance degradation or structural damage. By correlating noise occurrence with vessel loading conditions, a strong relationship was identified among gear transmission torque, the power distribution ratio between high-and low-pressure turbines, and the onset of knocking. Specifically, under low-load conditions, uneven power and torque distribution among the four gear branches led to insufficient loading on the low-pressure side. This light-load state induced instability in the low-pressure gears, resulting in periodic tooth disengagement or back-side tooth contact, which is established as the root cause of the knocking noise.
Gu, Chengzhong, Xu, Hanwei, Luo, Rirong, Ren, Fushan
Calculation and Test on Ultimate Burst Strength of Tubing2026-99-16057/24/2026
Tubing Ultimate burst strength Full scale test
Cheng, Wenjia, Yang, Hongbin, Ge, Yuan, Zhong, Chongdi, Meng, Lingkun, Ji, Bingyin, Shi, Jiaoqi
Experimental Study on The Parameters of the Viscoelastic-Plastic Constitutive Model of a Certain Solid Propellant2026-99-16047/24/2026
The mechanical behavior of a certain solid propellant is not only obviously related to time, temperature, and load loading history, but also is a viscoelastic plastic material under certain conditions. Based on the principle of creep deformation superposition, the strain of the solid propellant material is decomposed into a viscoelastic part and a viscoplastic part, and the nonlinearity of the viscoelastic-plastic constitutive model is manifested by the introduction of nonlinear coefficients. According to the characteristics of the viscoelastic-plastic model of the solid propellant material, the relevant tests were designed. The viscoplastic parameters were determined by using the creep recovery test data of multiple cycles until the failure of the propellant material sample. The viscoelastic parameters of the solid propellant material were obtained by using the data from recovery tests performed under different stress conditions.
Zhang, Jianbin, Sui, Jiuling, Yao, Baotai, Cheng, Dong, Li, Yiming
Optimization of Turbine Discrete Noise by Non-Uniformly Distributed Blade Design2026-99-16177/24/2026
The Mellin non-uniformly distributed moving blade method was adopted to conduct CFD numerical analysis and sample experimental tests on the axial-flow turbines before and after optimization using the uniformly distributed and non-uniformly distributed design methods, respectively. In the original design, five blades were evenly distributed in the 360° circumferential direction, and the non-uniformly distributed angles were 46°, 102°, 46°, 83°, and 83°. CFD numerical analysis shows that due to the low rotational speed of the turbine and the absence of a sealing structure at the blade tip, factors such as tip noise leakage and backflow have little impact, and the flow field pulsation is mainly caused by the blades themselves. The non-uniformly distributed design can significantly enhance the work-doing capacity of the blades. At 90% of the blade height, the torque can be increased by up to 60%, but at the same time, the axial force on the blades also increases accordingly. Near 80% - 90% of the blade height, the axial force increases by 33%. The flow rate performance of the non-uniformly distributed design is slightly inferior to that of the uniformly distributed design, but the overall noise is better than that of the uniformly distributed design, with maximum optimization of 0.48 dB (A); the maximum values of the first three orders of discrete noise are significantly improved, with a maximum improvement of 0.75 dB (A), and the discrete noise orders of the non-uniformly distributed turbine can avoid blade - related factors and disperse the energy to nearby orders.
Wu, Aiping, Ma, Tianli, Wang, Shiming, Ding, Chengling
A Review of Physical and Digital Infrastructure Standards and Guidelines to Support Deployment of Automated Vehicles in Rural Environments12-09-04-00307/23/2026
Connected and Automated Vehicles (CAVs) represent a transformative innovation poised to revolutionize roadway transportation by leveraging automated driving systems equipped with advanced sensors, high-performance computing, and communication technologies. While urban areas are the primary focus of current CAV developments, rural transportation systems risk being left behind despite the significant benefits that CAVs can bring to these regions. This article, therefore, explores the physical and digital infrastructure requirements for the safe deployment of CAVs in rural areas, drawing insights from standards, recommendations, and guidelines developed by leading standard organizations. The study highlights the specific design of physical infrastructure, including traffic signs, traffic signals, and pavement markings, and digital infrastructure, including communication, sensing, and mapping, to ensure rural communities are effectively prepared to benefit from the potential of CAVs. As its primary contribution, this article provides a comprehensive review of existing standards and guidelines relevant to rural CAV deployment. By synthesizing guidance across multiple standard-setting organizations, this review delivers a structured analytical assessment of existing standards, revealing their limitations and misalignment with rural transportation contexts while highlighting emerging good practices. The article clarifies the applicability of current guidance to rural infrastructure, identifies systemic infrastructure-related failure modes, and informs context-aware planning considerations for efficient and scalable CAV deployment in rural areas.
Zakaria, Mohammed, Getahun, Tesfamichael, Tavasoli, Mahsa, Pandey, Venktesh, Sarrafzadeh, Abdolhossein, Karimoddini, Ali
Research and Application of the Requirement Maturity Model in Civil Aircraft2026-99-18547/17/2026
Civil aircraft, as typical complex product systems, exhibit characteristics such as a high concentration of high-tech technologies, strong interdisciplinarity, a high level of system integration, long development cycles, substantial project investments, and complex management. During the R&D process of civil aircraft projects, there are often high risks in performance, cost, and schedule. Delays in the schedule can lead to losses in project manpower and material resources, as well as project failure. A mature objective criteria system for maturity assessment provides a reference basis for determining whether the project has reached its optimal state at a specific stage, thereby reducing project management risks and increasing the probability of project success. This research will adopt a research approach combining theoretical studies with practical case analysis. First, it will conduct extensive and in-depth investigations into various maturity models and their applications across the entire product lifecycle within relevant fields. A requirement maturity model and requirement maturity KPI (Key Performance Indicator) indicators will be established to clarify the maturity status of requirements at different development stages, enabling judgment of whether the project is ready to proceed to the next development phase. Concurrently, by developing a KPI statistical system platform integrating application servers and data processing tools, a scientific and quantitative inspection mechanism will be implemented to visualize project development progress, status, and risk data. This will provide actionable insights for project decision-making and achieve effective project management and control.
Wang, Yi, Huang, Junkai, Zhang, Xinyu
Calculation and Analysis of Civil Aircraft Depressurization2026-99-18347/17/2026
Analysis of cabin depressurization is key to ensuring civil aircraft airworthiness safety. In this study, we use a comprehensive approach to analyze depressurization scenes under regulations such as CCAR 25.841. For cases with and without cabin altitude warnings, we calculated critical leakage areas using an orifice flow model and iterative numerical methods. This combines inputs like emergency descent envelopes, air supply rates, and cabin parameters. In our analysis, we evaluate system failure impact and structural breaches on cabin pressure dynamics. For cases where the critical leakage area failed to meet the limits, we use an equivalent safety analysis based on the Depressurization Exposure Index (DEI). This combines pressure and exposure duration to measure physiological risks. We validated this approach through Simulink simulations and case studies, and found that it supports airworthiness verification, emergency descent optimization, and structural design improvements. This method provides a robust framework for enhancing civil aircraft depressurization safety.
Zheng, Bian
Design and Testing of a Quasi-Zero-Stiffness Vehicle-Mounted Isolation System with Additional Inerter2026-99-05207/10/2026
Vehicle vibrations during precision instrument transport can cause damage and failure. Existing vibration isolators often lack reliability, mass production feasibility, and easy maintenance. In this paper, we design and analyze a quasi-zero-stiffness vehicle-mounted isolator with an inerter, decreasing dynamic stiffness while raising the effective mass. Theoretical, simulation, and experimental results show improved isolation performance, lower isolation frequency, and a broader isolation bandwidth.
Li, Kai, Lv, Sibo, Sun, Ning, Dai, Shijie
Research on the Influence of Suspension Characteristics on Ride Quality of Railway Wagon2026-99-05117/10/2026
With the country’s economy and people’s consumption capacity increasing, railroad transportation tasks have become more and more frequent, and it is growing the demand for the transportation of high-value goods, fresh produce, etc. Compared with traditional Freight vehicles, express freight vehicles have great advantages in terms of carrying capacity, mobility, and transportation cost, but when it run at a speed of 160 km/h, it often occurs that failure of axle-box rubber springs, primary vertical dampers, secondary lateral dampers, anti-yaw dampers, and air springs. How to ensure the safety and stability of the train under suspension system failure conditions is a problem that needs to be solved during the design process. In this paper, through multi-body system dynamics software, a nonlinear dynamics model of lateral and vertical coupling of the vehicle system is established to analyze the influence of suspension system failure on the stability of 160 km/h express freight vehicles. The analysis results show lowering the operating speeds can meet the Ride Quality of the Vehicles in special conditions.
Gao, Zhixiong, Ma, Kai, Xiao, Yanmei, Chen, Weidong, Wei, Xiao, Sha, Chengyu, Bian, Huihui
Identifying and Mitigating Resonance Effects in HV Powernets: A Comprehensive Investigation into Current Ripple Effects in HV Power Nets2026-01-07427/1/2026
HV Power nets of electric vehicles consist of various HV components such as batteries, inverters, auxiliaries and cables. During in-vehicle testing, multiple failures of an auxiliary inverter were observed, caused by resonance issues within the component filter. Initial investigations revealed that these resonances, absent during manufacturer testbench evaluations, were influenced by the vehicle power net and its impedance characteristics. To better understand the underlying causes and identify preventative measures, extensive simulations were performed. The results demonstrate a diminishing influence of the power net capacitance when significantly larger than the component capacitance. Also, they highlight the critical impact of cable inductance on the component resonance frequency when comparable to the component’s inductance. A simplified electrical equivalent circuit was used to derive an equation predicting the resonance frequency as a function of the component’s capacitance/inductance and the cable length to the main power net capacitances. Based on these findings, recommendations for component filter design and testing protocols were proposed to mitigate similar failures in future applications.
Schmiel, Fabian, Aurand, Tobias, Koehnlechner, Benjamin, Zimmer, Markus
Influence of Common-Mode Voltage Reduction Techniques on High-Frequency Sideband Vibrations in IPMSM Drives for EVs2026-01-06956/20/2026
Space vector pulse width modulation (SVPWM) induces common-mode voltage (CMV) in three-phase voltage-source inverters, producing steep voltage edges that can lead to high leakage currents. In electric drive applications, these currents accelerate motor bearing degradation and may cause winding insulation failure. Active-zero-state PWM (AZSPWM) and near-state PWM (NSPWM) have been proposed as alternative modulation strategies to mitigate CMV and reduce drive degradation. This paper investigates the noise, vibration, and harshness performance of AZSPWM and NSPWM in comparison with conventional SVPWM. The proposed CMV reduction schemes are evaluated in terms of both CMV mitigation and their impact on high-frequency sideband vibration harmonics. Experimental results demonstrate that the CMV reduction strategies are highly effective in lowering CMV levels relative to SVPWM; however, this benefit is accompanied by an increase in vibration levels, which may adversely affect the mechanical integrity of the drive system despite the reduction in bearing leakage currents.
Khamis, Mahmoud Aly, Tatar, Andrei Alexandru, Repecho, Victor, Doria-Cerezo, Arnau
Unidirectional Carbon Fiber Tape Epoxy Repair Prepreg, Vacuum Curing Part 2 - Qualification Program for Fiber, Carbon Fiber Tape Prepreg, and Film AdhesiveAMS6885/2 (Current)6/10/2026
AMS6885/2 gives specific information about the qualification program for unidirectional carbon fiber tape epoxy repair prepreg capable of curing under vacuum for repair of carbon fiber reinforced epoxy structures. The prepreg system shall include an epoxy film adhesive to be applied in a co-bonding process with the prepreg for solid laminate and sandwich bonding.
AMS CACRC Commercial Aircraft Composite Repair Committee
Improvement of rCF Behaviour through the Introduction of NF2026-37-00396/9/2026
This study investigates the structural improvement of recycled carbon fibre composites through hybridisation with continuous flax fibres to address sustainability concerns and performance limitations. Recycled carbon fibres, while environmentally beneficial, suffer from short, randomized orientations and lower mechanical properties limiting their application beyond decorative uses. This research explores whether incorporating unidirectional flax fibres can enhance rCF behaviour for structural applications. Six hybrid composite layup variants and two plain composites were manufactured using cold compression moulding with Ampro Bio Resin. Each hybrid configuration comprised eight layers, divided into four layers of recycled carbon and four layers of flax fibres oriented at 0°. Complete mechanical characterization was performed following ISO standards for tensile (ISO 527), flexural (ISO 178), and impact (ISO 179) testing. Results demonstrated significant performance improvements in hybrid composites. Among hybrids, layup 2 achieved 212.5 MPa tensile strength whilst layup 3 managed to achieve 20.5 GPa in stiffness. Flexural testing revealed layup 6 achieved the highest flexural modulus of 19.6 GPa among hybrids. Impact resistance improved dramatically with layup 3 demonstrating 186% improvement in energy absorption over recycled carbon fibre. The study confirms that hybridisation creates a positive effect, producing more predictable and durable materials. The complementary behaviour between brittle and ductile materials enhances damage tolerance and structural integrity, establishing a foundation for sustainable engineering materials suitable for automotive applications without compromising reliability.
Hnatyk, Dawid, Chrysanthou, Andreas, De Vuyst, Tom, Ismail, Sikiru
Novel Material Architecture for Enhanced High Cycle Fatigue Life in Turbofan Engine Fan Blades2026-26-07486/1/2026
High Cycle Fatigue (HCF) is a critical failure mode in turbofan blades, primarily driven by resonance phenomena when the blade’s natural frequency aligns with engine-induced excitations. Traditional approaches to mitigate HCF often involve geometric modifications or damping treatments, which can adversely affect aerodynamic performance or increase component weight. This study explores alternative methodologies to strategically alter the natural frequency of turbofan blades while maintaining aerodynamic efficiency and structural integrity. A novel material architecture is proposed, consisting of a dual-metallic configuration with a high-stiffness core and a lightweight, fatigue-resistant outer shell. This design enables precise tuning of the blade’s dynamic response by leveraging the contrasting mechanical properties of the core and outer materials. The dual-metallic structure shifts the natural frequency away from critical excitation zones, thereby reducing the risk of resonance-induced fatigue failure. Additionally, the hybrid configuration contributes to weight reduction compared to conventional monolithic blade designs, offering further performance benefits. Comprehensive Finite Element Analysis (FEA) is employed to evaluate modal characteristics and stress distribution of turbofan blades. Results indicate that the proposed architecture achieves a favorable balance between dynamic stability, structural robustness, and aerodynamic performance. The dual-metallic blade design not only improves HCF life but also provides a scalable framework for future turbofan blade optimization.
S, Ravivarman, Inamdar, Prachi, De, Rohit
Effect of Fluid Flow/Time Duration on Static Voltage Generation for Aerospace Hose Assembly2026-26-07576/1/2026
Static electricity is an electrical imbalance on the surface of a material which can interact with other components having same or different materials. Fluid flow within the hose assembly generates static voltage due to friction caused by fluid flow in pipes, that needs to be appropriately quantified and dissipated. Accumulation of such static charge may lead to sudden discharge leading to spark generation. Spark generation around fuel flow might lead to system failure and failure in aircraft engines. Test experiments were conducted to analyze static voltage generated in hose assembly due to fuel flow with the objective that voltage achieved is within the acceptable range to avoid ESD (Electrostatic Discharge) failure. Procedure includes flow rate monitoring and voltage measurement using fuel as test fluid. The testing revealed that the curvature of the hose affects the readings, highlighting the importance of consistent meter alignment. Using a grounding strap is essential to prevent electrical damage and ensure accurate reading. Other functional factors such as proper set up and cleaning methods are crucial were also studied. It's important to check electrical continuity using an ohmmeter before testing. Initial results showed static voltage values beyond acceptable limits which may have resulted in ESD failure. The readings were optimized through electrical grounding and changes in the cleaning process. The revised static voltage readings increased with the flow rate non-linearly emphasizing that voltage testing is critical for aircraft safety.
Waghmare, Shashank
Hybrid Digital Twin for Aero-Engine Bearing Prognostics: A Physics-Informed Machine Learning Approach to RUL Prediction2026-26-07186/1/2026
Unscheduled maintenance due to the failure of critical components, such as aero-engine rolling element bearings, is a leading cause of costly Aircraft-on-Ground (AOG) events; consequently, current time-based maintenance practices are inefficient and prone to risk. This paper develops a resource-efficient Hybrid Digital Twin (HDT) model for an engine bearing, focusing on the dynamic prediction of spall growth due to Rolling Contact Fatigue (RCF), thereby enabling a condition-based maintenance paradigm. The HDT architecture integrates two core models: (1) a physics-informed model that uses established life and fatigue theory to define initial degradation thresholds, and (2) a data-driven Recurrent Neural Network (RNN), specifically a Long Short-Term Memory (LSTM) network, for dynamic degradation rate modeling. The methodology utilizes a Monte Carlo simulation coupled with RCF progression equations to generate a large, high-fidelity synthetic run-to-failure dataset under varying operational loads, accurately simulating realistic mission profiles. This approach addresses the critical "data scarcity" challenge in aviation. To ensure operational reliability, the framework incorporates Uncertainty Quantification (UQ) using Monte Carlo Dropout and addresses the "Sim-to-Real" gap through Transfer Learning on the NASA IMS bearing dataset. The HDT demonstrates a significant improvement in prognostic accuracy, achieving a Root Mean Square Error (RMSE) reduction of over 71% compared to baseline models. Furthermore, a cost-benefit analysis suggests a potential fleet savings of $240,000 per 100 engines by avoiding false negatives. This computationally efficient approach supports the Digital Engineering Transformation theme by providing a scalable blueprint for the virtual qualification of critical mechanical components.
Mohamed, Abbas
Hybrid Physics-Informed Neural Network and PID Control for Fault-Tolerant Autonomous Multi-Copters2026-26-07706/1/2026
This paper addresses the critical challenge of fault-tolerant control in autonomous multi-copters, particularly under conditions of one or two rotor failures a scenario that often leads to severe instability and a complete loss of directional control due to unbalanced torque and resultant autorotation. Existing advanced control strategies, including optimal approaches such as LQR, typically require precise system modeling and state estimation, which are difficult to achieve in real-world, dynamic failure scenarios. Alternative methods like fuzzy logic, sliding mode control, and gain-scheduling either lack robust generalization or are impractical for enumerating all possible failure cases. In this work, a hybrid control framework integrating Physics Informed Neural Networks (PINN) with a standard PID controller is proposed for fault-tolerant operation of autonomous multi-copters subject to multiple actuator failures. PINNs incorporate governing physical laws as regularization in their loss functions, allowing them to learn optimal counter-torque actions and thrust balancing necessary to arrest autorotation and stabilize flight, despite limited training data and uncertainty in failure conditions. The calculated moments and thrust commands are executed via a robust PID scheme, enabling reliable real-time implementation and minimizing residual oscillations. This hybrid control architecture demonstrates significant potential to enhance the resilience and operational safety of autonomous multi-copters during unexpected motor failures. By leveraging PINN’s physics-based generalization and PID’s consistent execution, the proposed method offers an adaptive, model-agnostic approach for maintaining stable flight and directional control under severe actuator faults, with implications for next-generation fault-tolerant UAV systems deployed in complex environments.
Charapalle, Samruddhi, Venugopalan, Nandagopalan, Nerkundram Muralidharan, Arun, Sundararaj, Laveen
Mitigating Cracking in COP Optics through Annealing and Step-Torquing2026-26-07646/1/2026
Polymeric optical materials such as Cyclo Olefin Polymer (COP) are adopted in aerospace lighting systems due to their excellent optical clarity, dimensional stability, moldability and weight saving advantages over glass. However, their relatively low toughness and the presence of residual molding stress make them prone to crack initiation during mechanical fastening. During its installation, crack formation was consistently observed around self-tapping screw interfaces, raising concerns over reliability, maintainability, and compliance with durability requirements. A structured Design of Experiments (DOE) was performed to identify root causes and evaluate potential mitigation methods. The investigation revealed that residual stresses in the COP material, combined with localized stress concentrations during screw tightening, were the primary drivers of crack initiation. Two complementary process improvements were identified and validated as part of mitigation plan: (i) annealing of the optics prior to assembly to relieve internal stress, and (ii) using step-torquing method to fasten the screws, to gradually distribute applied loads and reduce localized stress peaks. Post-assembly observation over three days confirmed a significant reduction in crack initiation. The combined annealing and step-torquing approach demonstrated a substantial reduction in crack generation probability, providing a practical and repeatable process for enhancing the robustness of polymeric optic assemblies. This work contributes a generalizable methodology for mitigating assembly-induced failures in advanced polymer materials and supports broader adoption of lightweight, high-performance optics in aerospace applications.
S, Nikhil, Singh, Abhimanyu Kumar, Katageri, Praveen, SP, Pradeep, Chandra, Praveen
Assessment of Injection Gate Location Effects on Mechanical Performance of Short Fiber Reinforced Plastic Components Using Digimat2026-26-07466/1/2026
The mechanical performance of short fiber-reinforced plastic (SFRP) components is highly sensitive to fiber orientation, which is significantly influenced by the injection gate location during the molding process. Traditionally, gate placement decisions are driven by warpage minimization strategies, often overlooking mechanical performance under diverse load cases. This research introduces an automated workflow within Digimat-MS that integrates injection gate optimization into the early design phase, leveraging Integrated Computational Materials Engineering (ICME) principles. The proposed methodology enables engineers to upload either Marc, Abaqus or Ansys input decks, select a component of interest, assign material cards, and define gate scenarios. A Design of Experiments (DOE) is then executed locally or remotely, allowing Digimat to evaluate multiple gate configurations. The system aggregates results and identifies optimal gate locations based on the initiation of failure under quasi-static loading conditions, thereby reducing reliance on trial-and-error and expert intuition. This approach not only streamlines the simulation process but also ensures that gate placement decisions are informed by comprehensive mechanical assessments across multiple load cases. The integration of Digimat’s ICME capabilities enhances simulation accuracy, leading to improved reliability and performance of SFRP components.
Kauthale, Tanmay, Madhavan, Vinay, Soni, Ganesh
Polymer vs. Metal Seals: A Comparison In Critical Space Systems26AERP06_036/1/2026
Sealing systems in space applications must perform reliably under demanding conditions in engineering: cryogenic temperatures, vibration, leakage control, ultra-high vacuum, ionizing radiation, abrasive particulates, and repeated thermal cycling. Each factor strains conventional sealing technologies. In combination, they can rapidly cause failure in systems where margins are unforgiving and maintenance is impossible. As spacecraft architectures evolve toward longer operational lifetimes and broader mission profiles, sealing requirements continue to tighten. Launch vehicles, satellites, and exploration platforms now operate across wider temperature ranges and in contact with more aggressive propellants and media. As a result, both metal seals and engineered polymer alternatives are evaluated-and selected-against increasingly specific, measurable performance criteria.
Reliability Program Standard Implementation GuideJA1000/1_202108 (Current)5/26/2026
The importance of reliability in design engineering has significantly grown since the early 1960’s. Competition has been a primary driver in this growth. The three realities of competition today are: world class quality and reliability, cost-effectiveness, and fast time-to-market. Formerly, companies could effectively compete if they could achieve at least two of these features in their products and product development processes, often at the expense of the third. However, customers today, whether military, aerospace, or commercial, have been sensitized to a higher level of expectation and demand products that are highly reliable, yet affordable. Product development practices are shifting in response to this higher level of expectation. Today, there is seldom time, or necessary resources to extensively test, analyze, and fix to achieve high quality and reliability. It is also true that the rapid growth in technology prevents the accumulation of historical data on the field performance of their products. Unfortunately, some reliability methods have depended upon the availability of historical data, other experiential information, or learning through extensive and time consuming tests. The new realities require innovation and creativity in the selection and use of reliability methods, and teamwork and collaboration in the management of product development programs. There must be a shift from seeking to eliminate complaints in products, to eliciting praise for them. To enable this transition, reliability efforts must be directed toward anticipating problems and designing-in features that assure the achievement of quality and reliability, concurrent with the development process, instead of trying to assess quality and reliability downstream. The gains in time-to-market and cost savings from such an approach can be significant. More recent reliability programs tend not to prescribe reliability tasks or methods to be performed by suppliers. Rather, suppliers are considered equal partners in the effort to produce a reliable product and work with the companies in deciding which reliability methods provide most value in achieving objectives. Nevertheless, developing reliable products and achieving reliability goals often requires different approaches for various product sectors. For example, in the defense/aerospace sector, the number of customers is relatively small. The product development cycle may span several years, while the product life cycle may last from mere minutes to as long as decades. Furthermore, it is not unusual for several design iterations of technologically different hardware and software to be developed before the final version is incorporated into the production product. Production volumes may range from rates of less than ten to hundreds per year. Also, the reliability discipline in this sector is generally a separate activity from the design discipline. The commercial sector, in contrast to the defense/aerospace sector, usually has a higher number of different customers. Development cycles could range from months to a few years while life cycles are often measured in years. Production volumes may run up to thousands per day. The reliability discipline is treated usually as an integral part of the up-front design process rather than a separate activity. Thus, developing a reliability implementation guide to meet the needs of all industry sectors is a formidable challenge. It recognized that this Guide will not strictly apply to all situations or industries. The suggestions made in this Guide must be interpreted in the context of the industry, its accepted practices, and unique company policies. The following statement will be repeated several times in this document to emphasize its importance: “The selection of methods is a highly individualized process. This point cannot be overemphasized and this document does not attempt to prescribe any given method or set of methods. There is no right answer that will apply across the board to every organization or every product development. Suppliers and customers need to determine which methods are most applicable to their specific product developments.”
G-41 Reliability
Items per page:
1 – 50 of 2954