Browse Topic: Crashworthiness

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Geometric Deep Learning–Based AI Framework for Nonlinear Crash Behavior of Extruded Rails15-19-03-00127/27/2026
Extruded Rails are critical energy-absorbing components in automotive structures designed to mitigate impact loads during the frontal collisions. Traditional crashworthiness design relies heavily on computationally expensive finite element simulations and iterative design exploration. This work proposes a machine learning–driven framework for rapid front extruded rails design using a trained geometric deep surrogate model. A design-of-experiments (DoE) was conducted by varying geometric parameters including width, height, and wall thickness of a thin-walled extruded rail structure. For each design variant, LS-DYNA simulations were performed to obtain performance metrics such as mean crush force and peak crush force. These simulation results were used to train an AI surrogate model capable of predicting crash responses directly from geometric parameters. The proposed approach significantly reduces computational cost by replacing repeated high-fidelity crash simulations with machine learning surrogate predictions. By enabling fast and accurate evaluation of crash response metrics, the workflow shortens design cycles and supports sustainability-driven crashworthiness assessment by reducing simulation resource usage. The framework establishes a scalable, simulation-driven engineering pathway across vehicle platforms and provides a foundation for future closed-loop, AI-assisted crash design workflows.
Kumar, Manik, Srinivasan, Sriram
Crashworthiness of WC19 Wheelchairs in Vertical Dynamic Aircraft Seating Tests09-14-02-00047/9/2026
Currently, people who use wheelchairs are not permitted to use their own wheelchairs as seats on commercial aircraft. To advance equitable aircraft travel for these passengers, we need to determine whether wheelchairs would be safe seating for their occupants and not pose a safety hazard for other passengers in case of emergency landing. We hypothesized that wheelchairs meeting the voluntary standards for vehicle crashworthiness (Rehabilitation Engineering Society of North America [RESNA] Section 19 Wheelchairs Used as Seats in Motor Vehicles [WC19]) would be able to pass the Federal Aviation Administration (FAA) vertical crashworthiness standards for aircraft seating. Wheelchairs were secured using surrogate 4-point strap tiedowns using the geometry specified by WC19. The FAA Hybrid III anthropomorphic test device (FH3 ATD) was restrained by both the wheelchair-attached lap belt and a vehicle-mounted lap belt identified as necessary to pass FAA dynamic horizontal test requirements. For the dynamic vertical testing with the wheelchairs oriented 60 degrees relative to horizontal, modeling demonstrated the suitability of using the trapezoidal pulse achieved with the UMTRI sled produced rather than the typical triangular shaped FAA pulse. Of the five manual and three power wheelchairs tested, four had broken components that would not impede emergency exit, four did not have visible damage, and the FH3 remained within the seat in all tests. The three power wheelchairs did not meet lumbar compression requirements. Based on these results, it may be feasible for people to use their own WC19-compliant wheelchairs on aircraft when secured to the aircraft with 4-point strap tiedown systems, supplemented by an occupant lap belt anchored to the aircraft, notwithstanding the lumbar force requirement.
Manary, Miriam A., Orton, Nichole Ritchie, Vallier, Tyler, Boyle, Kyle J., Klinich, Kathleen DeSantis
A Comprehensive Review of System Risk in Automotive Crash Safety15-19-02-00106/9/2026
Occupant protection has been at the forefront of risk evaluation regarding vehicle crashworthiness design. However, the vehicle is a member of a larger transportation system with varied stakeholders. This article identifies an opportunity for assessing risk in a crash event through emerging safety science paradigms. Conventional Safety I and Safety II frameworks handle well-defined hazards but falter with uncertainty, variability, and emergent behaviors in real crashes. A comprehensive literature review was performed on peer-reviewed research to situate automotive crash safety risk within the Safety III paradigms. The review addresses two questions: (1) How is “risk” defined across the crash safety literature and adjacent safety science domains? and (2) What limitations arise from these definitions in practice? Findings show a dominant probabilistic framing alongside a minority of system-oriented interpretations. Current crash safety practice lacks a coherent, system-level definition of risk that integrates uncertainty and knowledge strength, leading to fragmented methods and limited alignment with modern safety science. Based on this synthesis, the article proposes guiding principles for Safety III-aligned guidelines and recommendations that integrate consequences, uncertainty, and knowledge strength to improve transparency, traceability, and adaptability in crash safety decision-making.
Rye, Patrick J.
Occupant Sex Equity and Vehicle Safety: Historical Activities, Research, and Countermeasure2026-22-00025/28/2026
Since 2019, sex equity in traffic crashes has been a highly debated topic in vehicle safety, especially following the 2019 study by Forman et al. (1) claiming that female occupants face a 73 percent greater risk of serious injury in frontal crashes compared to male occupants. This was soon followed by a Consumer Reports Article by Keith Barry (2), which attempted to identify underlying factors contributing to the higher risk. These have been embraced by several parties since 2019. Firstly, it was alleged that vehicle design practice over the last four decades considered safety for the male population only and ignored that of the female as evidenced by the exclusive use of the mid-sized male Anthropomorphic Test Devices (ATDs) in Regulatory and Safety Ratings tests and not with an average sized female ATD. The absence of such an ATD for testing of vehicles “set the course for four decades’ worth of car safety design, with deadly consequences” (2). Secondly, although there is a recognition of the fact that Regulatory testing with a Small Female ATD, the Hybrid III-05F, was introduced in the FMVSS208 in 2003, this ATD was only a scaled version of the average male ATD of the 1970’s implying that this ATD is incapable of driving the design of restraint systems for females due to “They’re put together differently. Their material properties—their structure—is different” (2). Thirdly, according to a quote “These same trends have been observed in many, many studies in the past.” We assume that the trends refer to the apparent disparity in safety of females when compared to those of males. This document aims to outline historical activities, associated research and the development of countermeasures addressing crashworthiness concerns related to vehicle safety for females, as well as factors affecting both males and females, such as age-related impacts. This paper deals mainly with the frontal crash modes, mentions side impacts briefly as it affected designs of inflatable restraints for side impact to protect the smaller portion of the population from inflation induced injuries but the history behind the use of female ATDs by IIHS and NHTSA in full scale testing is not covered. Where ever possible, the time periods of reported activities related to female safety have been divided to pre-1997 corresponding to a change in US frontal crash regulation to address serious-to-fatal injuries to females and children, between 1997 to 2003 corresponding to the proposal by Canada for its frontal impact standard, and between 2003 and 2006 when the Advanced Restraint Regulation in the US FMVSS 208 was promulgated. This was followed by activities between 2007 and 2019, and post 2019 period.
Prasad, Priya, Dalmotas, Dainius J.
Letter from the Editor-in-Chief09-14-01-00015/13/2026
Letter from the Editor-in-Chief
Hardy, Warren N.
Maximizing Plastic Work in Crashworthy Rotorcraft Structures using Topology OptimizationF-0082-2026-02895/5/2026
We present a nonlinear topology optimization framework for designing crash--tolerant rotorcraft substructures by maximizing plastic work under prescribed crush displacement and volume constraints. The quasi-static response is modeled using a rate-independent elastoplastic formulation to capture path-dependent inelastic deformation of metallic components. A path-dependent adjoint method is developed to efficiently compute sensitivities of accumulated plastic work, revealing a mechanistic decomposition into elastic stiffness, deviatoric response, and yield surface contributions. Optimized 2D and 3D subfloor structures develop emergent plastic hinge networks and distributed deformation paths, significantly enhancing energy absorption compared to uniform designs. The results demonstrate that topology optimization can directly embed energy-dissipating mechanisms into primary rotorcraft structures, providing a practical framework for crashworthy rotorcraft and eVTOL airframe designs.
Das, Ghanendra, James, Kai, Kennedy, Graeme
Frontal Crash Classification and Occupant Outcomes from 2017 to 2023 US Field Cases09-14-01-00245/4/2026
This study provides an updated characterization of real-world frontal crash types—considering overlap and obliquity—based on their overall frequency and associated injury outcomes. The results of this study will support an evaluation of how well NHTSA’s frontal oblique crash test condition addresses the current population of serious frontal crashes, as compared to frontal test modes in existing crashworthiness programs. U.S. field crash data from 2017 to 2023 were analyzed to classify frontal crashes by coded damage characteristics. Oblique frontal crashes were defined as those with principal direction of force between 10°–40° and 320°–350°. Non-ejected belted first and second row occupants in model year 2000 and newer passenger vehicles absent a rollover event were included. Occupants were stratified by sex, age, and body mass index, and injury outcomes based on moderate, serious, and fatal thresholds were analyzed across crash configurations. Among the belted first row occupants considered in this study, more than 45% were exposed to oblique crashes while full overlap colinear crashes accounted for 18% of the occupants. Oblique crashes represent a disproportionately large number of AIS 3+ injured and fatal occupants. Older occupants and females showed a trend of higher injury frequency despite less exposure. Full overlap crashes still account for a representative portion of serious injuries among frontal crashes. Limitations include restriction of cases to those with complete vehicle and occupant details. Assessment of impact type was dependent on generic vehicle class-specific reference values. The findings reinforce the enduring relevance of oblique frontal crash conditions which remain a substantial contributor to serious injuries and fatalities, especially for older adults and female occupants.
Rudd, Rodney W.
Effective Design Method for Lightweight Suite of Seats Considering Crashworthiness and Cost2026-01-04934/7/2026
This paper presents a methodology for designing and evaluating lightweight, crashworthy aircraft seats that meet 21g crash safety standards and injury criteria. Four seat classes—double economy, single economy, premium economy, and business—were developed using a modular design strategy focused on part commonality (family of parts) and manufacturability. A shared family of structural components was implemented across all seat types, with dimensional modifications applied only, when necessary, due to differences in seat width or height. In such cases, the same material systems and design principles were used to ensure consistency and reduce manufacturing complexity. The designs were evaluated using finite element simulations to verify performance under aerospace crash conditions. Each seat configuration was validated against regulatory crashworthiness criteria and injury thresholds, including pelvic, lumbar, and femur compressive forces, as well as head injury criteria (HIC) values. The final designs successfully passed all crash and most injury thresholds, achieving regulatory compliance while maintaining a lightweight structure. This marked a significant improvement over a baseline seat configuration that failed to meet crash or injury requirements. By combining modularity with performance-driven design, this approach delivers a flexible and manufacturable seat family that balances safety, weight, and cost. The methodology offers broader applicability for occupant protection systems in automotive and aerospace domains, where lightweighting and regulatory compliance remain critical design challenges.
Gray, Savannah, Orr, Mathew, Shi, Yifan, Park, Taeil, Lee, Jake, Wotten, Erik, LeFrancois, Richard, Huang, Yuhao, Patel, Anuj, Kim, Hansu, Burns, Nicholas, Jalayer, Shayan, Grant, Robert, Kok, Leo, Hansen, Eric, Kim, Il Yong
Optimizing Weld Placement in Automotive Structures Using Topology and Multi-Disciplinary Approaches2026-01-05144/7/2026
This work presents two approaches for weld optimization aimed at reducing manufacturing cost and process time, while meeting structural performance requirements in automotive structures. The first approach uses topology optimization to identify the most efficient weld layouts. A design space is generated along mating flanges, joints, and panel interfaces, where potential weld locations are defined. Welds are treated as discrete design variables, and the topology optimization systematically evaluates their contribution to global stiffness and load path integrity. Non-critical welds, those with minimal impact on stiffness, durability, or crashworthiness, are eliminated, resulting in a minimized weld pattern that maintains structural performance. The second approach applies Multi-Disciplinary Optimization (MDO) to balance weld reduction with performance targets across multiple domains, including linear and non-linear stiffness, crashworthiness, and fatigue. Using a preprocessing tool, welds are parameterized to allow flexible control of their placement. A Design of Experiments (DoE) is generated to simulate various weld configurations under relevant load cases. Surrogate models are then developed to approximate the relationship between weld layout and key performance metrics. These response surfaces enable efficient optimization that minimizes weld count while satisfying all structural requirements. Together, these strategies form a data-driven, simulation-based framework for weld design that supports aggressive cost and time reduction targets without compromising safety or durability. The results demonstrate the potential for integrating advanced optimization techniques into early design phases for more efficient and manufacturable vehicle structures.
Koppaka, Vinaya, Yoo, Dong Yeon, Chavare, Sudeep
A Study on the Relationship between Impact Conditions and Head Injury Criterion (HIC) in Powered-Two-Wheeler to Car Crashes2026-01-05714/7/2026
Road Traffic crash statistics highlight the importance of reducing fatalities among Powered-Two-Wheeler (PTW) riders, and suggest the necessity of a robust method to evaluate PTW crashworthiness performance. The objective of this study is to clarify the relationship between impact conditions and the Head Injury Criterion (HIC) to establish a fundamental basis for determining representative crash configurations for safety. A total of 1,272 PTW-front to car-side impact simulations were conducted by using production car and PTW models. HIC was used as a metric indicating likelihood of head injury. Velocities, impact angle, and impact locations were varied to create response surfaces. The surfaces were evaluated in terms of their accuracy in identifying the representative impact conditions. In addition, head trajectories were analyzed to clarify the kinematics until head impact. The Finite Element (FE) simulations produced the following findings. The HIC distribution by Head Impact Target can be categorized into 2 groups by the height of the car roof. Some of the low-roof car group results show a phenomenon of partial helmet removal, causing large variation in HIC. High HIC values are observed when the Y-direction displacement at the head impact is small. Structural stiffness and roof height may need to be considered when investigating a future test method that provides stable safety evaluation. These findings establish a fundamental basis for determining the representative crash scenario through an analysis of the relationship between crash conditions and the HIC.
Yanaoka, Toshiyuki, Gunji, Yasuaki, Zulkipli, Zarir Hafiz, Matsushita, Tetsuya, Carroll, Jolyon, Puthan, Pradeep, Mohd Faudzi, Siti Atiqah, D-Wing, Kak, Miyazaki, Yusuke
Multi-Material Topology Optimization Using Difference-Based Equivalent Static Load Method2026-01-01734/7/2026
Topology optimization (TO) has become a powerful tool for generating lightweight structural designs. TO has been widely applied to linear static problems, where analytical sensitivities are easy to obtain. However, crashworthiness design requires nonlinear dynamic analysis, for which analytical sensitivities are generally not available. To extend TO into crash problems, approximation methods such as the Equivalent Static Load (ESL) method have been developed. ESL replaces the nonlinear problem with a series of linear static subproblems, ensuring that the displacement fields match at certain time steps. These subproblems can then be efficiently solved using standard TO techniques. A key limitation of ESL is that it relies on the initial mesh for all subproblems, which reduces accuracy for highly nonlinear crash responses. To address this, Triller proposed the difference-based ESL (DiESL) method, which updates the mesh in each subproblem to the deformed configuration, therefore improving approximation accuracy. However, existing DiESL implementations are restricted to single-material topology optimization (SMTO), where elements can be either solid or void. In contrast, multi-material topology optimization (MMTO) allows multiple material candidates per element, offering greater design freedom and the potential for better solutions. For crashworthiness applications, MMTO can leverage low-density materials (e.g., aluminum or magnesium) to form thick members that resist buckling, while using high-strength, high-density materials (e.g., steel) in critical stress regions to prevent yielding. By combining MMTO with DiESL, nonlinear crash performance can be further improved, offering a promising framework for lightweight and crashworthy structural design.
Huang, Yuhao, Kim, Il Yong
Ambulance Patient Compartment Seating Integrity and Occupant RestraintJ3026_202602 (Current)2/18/2026
This SAE Recommended Practice describes the testing procedures that may be used to evaluate the integrity of ground ambulance-based occupant seating and occupant restraint systems for workers and civilians transported in the patient compartment of an ambulance when exposed to a frontal or side impact. This recommended practice was based on ambulance patient compartment dynamics and is not applicable to other vehicle applications or seating positions. This recommended practice is structured to accommodate seating systems installed in multiple attitudes including, but not limited to, side-facing, rear-facing, and forward-facing. Its purpose is to provide ambulance seating manufacturers, ambulance occupant restraint manufacturers, ambulance builders, and end users with testing procedures and, where appropriate, acceptance criteria that, to a great extent, ensures the occupant seating and occupant restraint system meet similar performance criteria as FMVSS 208 requires for seat belted passengers in light vehicles. The test conditions utilized are standardized orientations that do not reflect potential conditions that may exist prior to impact such as braking and/or steering and their effects on the initial positions of the occupants and surfaces relative to the occupants. Descriptions of the test setup, test instrumentation, photographic/video coverage, text fixture, and performance metrics are included.
Truck Crashworthiness Committee
Steering Control Systems - Heavy TrucksJ2425_202601 (Current)1/27/2026
This SAE Recommended Practice describes a laboratory test procedure and requirements for evaluating the characteristics of heavy-truck steering control systems under simulated driver impact conditions, as well as driver entry/egress conditions. The test procedure employs a torso-shaped body block that is impacted against the steering wheel.
Truck Crashworthiness Committee
Crashworthiness of WC19 Wheelchairs in Horizontal Dynamic Aircraft Seating Tests09-14-02-00011/23/2026
At present, commercial air travel rules do not allow people to sit in their own wheelchairs during flight. However, airline seating often does not meet medical needs. In response to current requests to allow this seating option, we researched the crashworthiness and safety of wheelchairs for potential use in aircraft. For motor vehicle travel, many wheelchairs meet voluntary standards for crashworthiness and safety per RESNA WC19. This project assesses whether WC19-compliant wheelchairs can meet FAA aircraft seating standards when secured using 4-point tiedowns. For the FAA horizontal impact testing, computer modeling indicated that a trapezoidal sled pulse was sufficient to represent the more typical triangular pulse, and that due to the flexibility of the tiedown webbing, the effect of the simulated pitch/roll element was minimal. During the initial two horizontal impact tests, fracture of the left front wheelchair caster was observed. The remaining five wheelchairs were tested with an added vehicle-mounted lap belt and were successful at meeting occupant retention and structural integrity requirements. The outcomes show that it may be possible for people to remain seated in a WC19-compliant wheelchair for air travel without a significant decrement in safety.
Klinich, Kathleen D., Manary, Miriam A., Boyle, Kyle J., Vallier, Tyler, Orton, Nichole R.
Enhanced Integrated Cooling-Protection Plate for Battery pack Underbody Impact Resistance in Electric Vehicles2026-26-01691/16/2026
In the quest for enhancing electric vehicle performance and safety, this paper presents a comprehensive investigation into the design and performance of high-voltage (HV) battery cooling plates featuring dedicated cooling channels, integrated with structural bottom protection members. The study aims to address the dual challenges of thermal management and crash protection in electric vehicles during bottom impacts. The research evaluates the cooling efficiency and structural resilience of the proposed design through a combination of design iterations, thermal performance evaluation, and crash simulations. Findings reveal that the integrated cooling plates not only maintain optimal battery temperatures under various operating conditions but also significantly improve the vehicle's crashworthiness. It was found that the cooling efficiency of the HV battery plates improved compared to competitor’s design, resulting in a more stable thermal environment for the battery cells. Moreover, dedicated cooling channels result in a lower maximum battery temperature, with the temperature difference within the heated surface being less than 5 °C under peak load conditions. This leads to a more uniform temperature distribution and significant reductions in hot spots. Additionally, integrating structural crash members increased the energy absorption capacity by 33%, enhancing the vehicle's crashworthiness during bottom impacts when compared to no integrated structural crash members. The combined design led to around 14% reduction in the overall weight of the battery module, contributing to better vehicle performance and efficiency.
Dusad, Sagar, Kummuru, Srikanth, Joshi, Amarja
Multi-Material Front Structures: A Pathway to Safer and More Sustainable Vehicle Design2026-26-04561/16/2026
Frontal crash structures play a vital role in occupant safety, but traditional designs often involve a trade-off between structural strength and weight efficiency. In the pursuit of safer and more sustainable mobility, this study explores a physics-based methodology that leverages the principle of dynamic equilibrium to guide the integration of dissimilar materials in front-end vehicle structures. Specifically, examined a novel configuration wherein aluminum High-pressure die cast (single HPDC part) is introduced which covers swan neck region as well as the base of the front longitudinal member, while retaining steel in the frontal crush zone. This arrangement aims to redistribute crash loads and control deformation mechanisms, enabling improved energy absorption without compromising structural integrity. To evaluate the proposed strategy, a series of detailed finite element simulations were conducted using LS-DYNA, a widely adopted tool for vehicle crash analysis. The results reveal that the dynamic equilibrium approach offers a rational and most efficient framework for material allocation, allowing for the optimization of crash performance metrics while simultaneously achieving weight reduction. Compared to conventional all-steel or all-aluminum designs, the hybrid structure demonstrate efficient, improved crashworthiness, with measurable mass savings. By grounding material decisions in mechanical principles rather than empirical iteration, this research presents a scalable methodology applicable to a wide-range of vehicle platforms. The outcomes offer a compelling case for the adoption of multi-material architectures as a pathway toward enhanced crash safety and reduced environmental impact.
Revanth, Goshika, Bhagat, Milind, Joshi, Vikas, Mankhair, Abhijit, Sudarshan, B.Sudarshan, Kollipara, Jahanavi
Influence of Impact Configuration on Rear Compartment Intrusion and Structural Countermeasures2026-26-04621/16/2026
The impact configuration has a strong influence on the rear seat survival space intrusion pattern during severe rear-impact collisions. The relative contributions of rear seat pan forward intrusion versus rear seatback intrusion vary depending on the nature of the crash. In underride impacts, the rear wheels are pushed forward into the occupant survival space from below, causing the rear seat-pan to move forward and upward relative to the vehicle interior. Conversely, override impacts tend to produce direct seatback intrusion into the rear compartment. This study used a validated computer model from the NHTSA website to simulate various types of rear compartment intrusions under different impact configurations. The analysis also assessed structural countermeasures designed to minimize occupant survival space intrusion. The results demonstrate that underride impacts primarily drive the forward motion of the rear wheels into the structure, establishing load paths that lead to structural failures and forward propulsion of the seat pan, in contrast to the seatback-dominant intrusion observed in override impacts. Furthermore, the study shows that structural reinforcements located above, and below the beltline are effective in mitigating survival space intrusion across different rear-impact scenarios.
Thorbole, Chandrashekhar, Vhanaje, Manoj G, Eknath Chopade, Santosh
Experimental Study on the Role of Hole Expansion Ratio in Enhancing Crashworthiness of Advanced High Strength Steel2026-26-02951/16/2026
To meet light weighting and safety targets, the automotive industry is increasingly using advanced high strength steel (AHSS) materials and advanced manufacturing techniques for complex body parts. To improve energy absorption of automotive body parts, various steel grades are developed by steel manufactures with variety of properties (YS, UTS, EL %, HER). Also, the formability of AHSS grades (TS > 980 MPa) is challenging due to its limited edge ductility. This study focuses on role of hole expansion ratio (HER) in energy absorption of AHSS material. In the study, different AHSS material with variety of microstructure and properties are experimented, with the aim to identify the optimum properties that can help to enhance crash worthiness of formed part. From experimentation, it is evident that hole expansion ratio plays an important role in determining edge ductility, as well as energy absorption. This study may not only help to improve crash performance but also help for light-weighting of automotive body parts.
Jain, Vikas, Bandru, Shreenu, Nadarge, Harshad, Misal, Swapnali, Deshmukh, Mansi, Paliwal, Lokesh
Crash Pulse Characterization for the Passenger Vehicle Fleet in India2026-26-00291/16/2026
A crash pulse is the signature of the deceleration experienced by a vehicle and its occupants during a crash. The deceleration-time plot or crash pulse provides key insights into occupant kinematics, occupant restraints, occupant loading and efficiency of the structure in crash energy dissipation. Analysing crash pulse characteristics like shape, slope, maximum deceleration, and duration helps in understanding the impact of the crash on occupant safety and vehicle crashworthiness. This paper represents the crash pulse characterization study done for the vehicles tested at ARAI as per the ODB64 test protocol. Firstly, the classification and characterization of the crash pulses is done on the basis of the unladen masses of the vehicles. The same are further analysed for suitability of mathematical waveform models such as Equivalent Square Wave (ESW), Equivalent Triangular Wave (ETW), Equivalent Sine Wave (ESW), Equivalent Haversine Wave (EHSW) as well as EDTW (Equivalent dual trapezia wave) or Bi Slope Approximation model for the characterization. These mathematical wave diagrams are then utilized for analysing the crash behaviour and its probable effect on the injury probability. Such a study can be used by design engineers to model the front-end stiffness of the vehicle frontal structure. This can further help to optimize the dummy restraint modifications to minimize the occupant injury.
Mishra, Satish, Kulkarni, Dileep, Borse, Tanmay, Mahindrakar, Rahula Ashok, Mahajan, Rahul, Jaju, Divyan
Safer Trucks for India: Smart Tech Fusion2026-26-00311/16/2026
Commercial vehicle sector (especially trucks) has a major role in economic growth of a nation. With improving infrastructure, increasing number of trucks on roads, accidents are also increasing. As per RASSI (Road Accident Sampling System India) FY2016-23 database, commercial vehicles are involved in 42% of total accidents on Indian roads. Involvement of trucks (N2 & N3) is over 25% of total accidents. Amongst all accident scenarios of N2 &N3, frontal impacts are the most frequent (26%) and causing severe occupant injuries. Today, truck safety development for frontal impact is based on passive safety regulations (viz. front pendulum – AIS029) and basic safety features like seatbelts. In any truck accident, it is challenging rather impossible to manage comprehensive safety only with passive safety systems due to size and weight. Accident prevention becomes imperative in truck safety development due to extremely high energy involved in front impact scenarios. The paper presents a unique safety development approach (for frontal impact safety development for N2 and N3 trucks) which enables smart synthesis of active and passive safety systems to comprehensively address real world safety. Four major areas are identified for truck safety development viz. structural crashworthiness, compatibility, occupant safety and ADAS (Advanced Driver Assistance System). The innovation lies in smart mix of these areas during product safety development. The study presents the safety development of light commercial vehicle (truck) with this approach. Structural crashworthiness & occupant safety are developed with extensive number of CAE simulations. Design is physically validated with frontal impact test. In addition, extensive mileage accumulation is generated across Indian roads to validate ADAS system performance.
Joshi, Kedar Shrikant, Gadekar, Ganesh, Date, Atul, Koralla, Sivaprasad
Optimization of Frontal Impact Force Scheme to Accelerate the Target Setting Process for Development of Front-End Structures in Vehicles2026-26-00011/16/2026
A passenger vehicle's front-end structure's structural integrity and crashworthiness are crucial to ensure compliance with various frontal impact safety standards (such as those set by Euro NCAP & IIHS). For a new front-end architecture, design targets must be defined at a component level for crush cans, longitudinal, bumper beam, subframe, suspension tower and backup structure. The traditional process of defining these targets involves multiple sensitivity studies in CAE. This paper explores the implementation of Physics-Informed Neural Networks (PINNs) in component-level target setting. PINNs integrate the governing equations into neural network training, enabling data-driven models to adhere to fundamental mechanical principles. The underlying physics in our model is based upon a force scheme of a full-frontal impact. A force scheme is a one-dimensional representation of the front-end structure components that simplifies a crash event's complex physics. It uses the dimensional and positional parameters of the components, along with their force-displacement curves, to estimate the vehicle's crash pulse. In this work, we have implemented PINNs to generate an optimized force scheme using the historical CAE test data. Using this approach promises to cut short the time and cost that goes into the conventional process of target setting.
Gupta, Ishan, Bhatnagar, Abhinav, Kumar, Ayush
Enhancing Energy Absorption in Rear Impact Events through Rail Extension Design and Material Variations2025-36-009612/18/2025
Safety improvements in vehicle crashworthiness remain a primary concern for automotive manufacturers due to the increasing complexity of traffic and the rising number of vehicles on roads globally. Enhancing structural integrity and energy absorption capabilities during collisions is paramount for passenger protection. In this context, longitudinal rails play a critical role in vehicle crashworthiness, particularly in mitigating the effects of rear collisions. This study evaluates the structural performance of a rear longitudinal rail extender, characterized by a U-shaped, asymmetric cross-section, subjected to rear-impact scenarios. Seventy-two finite-element models were systematically developed from a baseline configuration, exploring variations in material yield conditions, sheet thickness, and targeted geometric modifications, including deformation initiators at three distinct positions or maintaining the original geometry. Each model was simulated according to ECE R32 regulation standards, ensuring validity and compliance with relevant safety criteria. Specific energy absorption (SEA), load uniformity, and structural acceleration were used as key measures of crashworthiness. Simulation outcomes indicated that reductions in thickness significantly increased SEA due to enhanced deformability. Thinner configurations demonstrated greater energy absorption and improved load uniformity, whereas thicker components increased structural rigidity, resulting in decreased energy absorption and higher accelerations transmitted to the vehicle’s B-pillar. Material properties had moderate influence, with higher-strength materials elevating accelerations. Geometric modifications, particularly deformation initiators at specific positions, substantially improved SEA, achieving enhancements up to 42% compared to baseline. These findings highlight the potential of strategic adjustments in geometry, material selection, and thickness to significantly enhance vehicle crashworthiness and occupant safety.
Souza Coelho Freitas, Victor de, Pereira, Romulo Franco, Souza, Daniel Souto de
Cab Roof Strength Evaluation - Quasi-Static Loading Heavy TrucksJ2422_202507 (Current)7/22/2025
This SAE Recommended Practice describes the test procedures for conducting quasi-static cab roof strength tests for heavy-truck applications. Its purpose is to establish recommended test procedures that will standardize the procedure for heavy trucks. Descriptions of the test setup, test instrumentation, photographic/video coverage, and test fixtures are included.
Truck Crashworthiness Committee
Ambulance Equipment Mount Device or SystemsJ3043_202505 (Current)5/27/2025
This SAE Recommended Practice describes the dynamic and static testing procedures required to evaluate the integrity of an equipment mount device or system when exposed to a frontal or side impact (i.e., a crash impact). Its purpose is to provide equipment manufacturers, ambulance builders, and end users with testing procedures and, where appropriate, acceptance criteria that, to a great extent, ensure equipment mount devices or systems meet the same performance criteria across the industry. Prospective equipment mount manufacturers or vendors have the option of performing either dynamic testing or static testing. Descriptions of the test setup, test instrumentation, photographic/video coverage, test fixture, and performance metrics are included.
Truck Crashworthiness Committee
Towards Crash-Tolerant Rotorcraft Design via Topology OptimizationF-0081-2025-02325/20/2025
We present our ongoing efforts towards the development of crash-tolerant rotorcraft airframe structures through topology optimization, with the goal of enhancing energy absorption and occupant survival during vertical impact events. A high strain rate explicit dynamics solver has been developed, fully accelerated on GPUs, to enable rapid and accurate simulation of impact events critical to crashworthiness evaluation. In parallel, we have built a scalable three-dimensional topology optimization framework that enforces stiffness, weight, and frequency constraints simultaneously, driving structurally efficient and vibration-resistant designs. Benchmarking results demonstrate significant GPU-enabled speedups, facilitating high-fidelity crash simulations and large-scale optimization at practical turnaround times. This work establishes a computational foundation for future integration of crash-centric objectives and constraints into the optimization framework.
Das, Ghanendra, James, Kai, Kennedy, Graeme, Webb, Lonnie, Oluwalana, Daniel
Occupant Restraint and Equipment Mounting Integrity - Rear Impact Ambulance Patient CompartmentJ3044_202505 (Current)5/20/2025
This SAE Recommended Practice describes the test procedures for conducting rear impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mount testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Occupant Restraint and Equipment Mounting Integrity - Side Impact Ambulance Patient CompartmentJ2956_202505 (Current)5/20/2025
This SAE Recommended Practice describes the test procedures for conducting side impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mounting testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Impact of Harness Integrated Crash RestraintsF-0081-2025-02705/20/2025
The Crashworthy and Escape Systems Branch at NAWCAD has been developing an integrated restraint harness concept for several years, with the intent of developing a novel method of providing improved occupant protection in a crash scenario. A series of tests was conducted on the Horizontal Accelerator at NAS Patuxent River to evaluate the performance of the prototype integrated-restraint system under MIL-STD-58095 conditions with the 50th percentile male Hybrid III Anthropomorphic Test Device (ATD). While occupant flail was the primary metric being analyzed in this effort, ATD instrumentation was also captured, showing that the integrated restraint system demonstrated a significant reduction in head flail compared to five-point restraints while maintaining injury criteria within acceptable levels.
Anderson, Eric, Minnich, Shannon
Development of a Generic Nearside Impact Test Fixture for Evaluating In-Vehicle Crashworthiness of Wheelchairs2025-22-00025/13/2025
Current voluntary standards for wheelchair crashworthiness only test under frontal and rear impact conditions. To help provide an equitable level of safety for occupants seated in wheelchairs under side impact, we developed a sled test procedure simulating nearside impact loading using a fixed staggered loading wall. Publicly available side impact crash data from vehicles that could be modified for wheelchair use were analyzed to specify a relevant crash pulse. Finite element modeling was used to approximate the side impact loading of a wheelchair during an FMVSS No. 214 due to vehicle intrusion. Validation sled tests were conducted using commercial manual and power wheelchairs and a surrogate wheelchair base fixture. Test procedures include methods to position the wheelchair to provide consistent loading for wheelchairs of different dimensions. The fixture and procedures can be used to evaluate the integrity of wheelchairs under side impact loading conditions.
Boyle, Kyle, Hu, Jingwen, Manary, Miriam, Orton, Nichole R., Klinich, Kathleen D.
Influence of Strain Rate Effect on Mechanical and Crashworthiness Properties of CFRP Composite Structures05-19-01-00025/6/2025
Composite materials are increasingly utilized in industries such as automotive and aerospace due to their lightweight nature and high strength-to-weight ratio. Understanding how strain rate affects the mechanical and crashworthiness properties of CFRP composites is essential for accurate impact simulations and improved safety performance. This study examines the strain rate sensitivity of CFRP composites through mechanical testing and finite element analysis (FEA). Experimental results confirm that compressive strength increases by 100%–200% under dynamic loading, while stiffness decreases by up to 22% at a strain rate of 50 s−1, consistent with trends observed in previous studies. A sled test simulation using LS-Dyna demonstrated that the CFRP crash box sustained an average strain rate of 46.5 s−1, aligning with realistic impact conditions. Incorporating strain rate–dependent material properties into the FEA model significantly improved correlation with experimental crashworthiness data, reducing discrepancies in peak acceleration, mean acceleration, and displacement by 6.5%, 5.9%, and 6.3%, respectively. These findings reinforce the necessity of accounting for strain rate effects in crash simulations and composite structure design, ensuring more accurate predictions of impact performance and structural integrity in safety-critical applications.
Badri, Hesam, Jayasree, Nithin Amirth, Loukodimou, Vasiliki, Omairey, Sadik, Bradbury, Aidan, Lidgett, Mark, Page, Chris, Kazilas, Mihalis
A Low-Entry Bus Body Structure Performance under the Conditions of the New Car Assessment Program Frontal Crash Tests09-13-02-00074/9/2025
The New Car Assessment Program (e.g., US NCAP and EuroNCAP) frontal crash tests are an essential part of vehicle safety evaluations, which are mandatory for the certification of civil means of transport prior to normal road exploitation. The presented research is focused on the behavior of a tubular low-entry bus frame during a frontal impact test at speeds of 32 and 56 km/h, perpendicular to a rigid wall surface. The deformation zones in the bus front and roof parts were estimated using Ansys LS-DYNA and considered such factors as the additional mass (1630 kg) of electric batteries following the replacement of a diesel engine with an electric one. This caused stabilization of the electric bus body along the transverse axis, with deviations decreased by 19.9%. Speed drop from 56 to 32 km/h showed a reduction of the front window sill deformations from 172 to 132 mm, and provided a twofold margin (159.4 m/s2) according to the 30g ThAC criterion of R80. This leads to the conclusion about the recommendation to reduce the regulatory NCAP speed for city buses to ensure a sufficient safety margin, especially considering the city speed limit of 40–50 km/h. The novelty consists in the application of the NCAP regulations, which is not typical for buses, with the formation of conclusions about the higher danger for passengers compared to UNECE R29 due to the much deeper penetration of plastic deformations into the bus body (up to the rear axle). The obtained results can influence accident prevention strategies and the revision of the city bus certification approaches and regulations.
Holenko, Kostyantyn, Dykha, Aleksandr, Koda, Eugeniusz, Kernytskyy, Ivan, Royko, Yuriy, Horbay, Orest, Berezovetska, Oksana, Rys, Vasyl, Humeniuk, Ruslan, Berezovetskyi, Serhii, Chalecki, Marek
Exploring Hybrid TPMS Designs for Improved Energy Absorption2025-01-87264/1/2025
Triply Periodic Minimal Surface (TPMS) structures have gained significant attention in recent years due to their excellent mechanical properties, lightweight characteristics, and potential for energy absorption in various engineering applications, particularly in automotive safety. This study explores the design, manufacturing, and mechanical performance of both general and hybrid TPMS structures for energy absorption. Three types of fundamental TPMS unit cells—Primitive, Gyroid, and IWP—were modeled using implicit functions and combined to form hybrid structures. The hybrid designs were optimized by employing Sigmoid functions to achieve smooth transitions between different unit cells. The TPMS structures were fabricated using Selective Laser Melting (SLM) technology with 316L stainless steel and subjected to quasi-static compression tests. Numerical simulations were conducted using finite element methods to verify the experimental results. The findings indicate that hybrid TPMS structures exhibit superior energy absorption characteristics compared to individual unit cells, with notable improvements in specific energy absorption and structural stability under compressive loads. Furthermore, this study demonstrates the potential application of hybrid TPMS structures in automotive crash box, offering enhanced crashworthiness and multi-stage energy regulation.
Liu, Zhe, Wang, MingJie, Guo, Pengbo, Li, Youguang, Lian, Yuehui, Zhong, Gaoshuo
Material Characterization of Newly-Developed Advanced High Strength Steels for Prediction of Crash Performance2025-01-82204/1/2025
New highly ductile advanced high strength steel (AHSS) grades with tensile strength greater than 980 MPa have been developed with the aim of achieving a combination of high strength and excellent formability. The new jetQTM-Family [1, 2] offers high local and global ductility, which is expected to contribute to the improvement of vehicle crash performance. For the reliable design and management of vehicle crash performance, material modeling, including work hardening behavior and material failure strain, plays an important role in numerical simulation. Especially, the accuracy of material failure prediction is important for the development of crash performance. In this study, the fracture behaviors of 980jetQTM, 1180jetQTM, and conventional Dual-Phase (DP) steels are investigated through simple tensile and V-bending fracture tests incorporating experimental-numerical hybrid ductile fracture analysis. Based on the experimental results, the ductile fracture parameters in the Hosford-Coulomb fracture model [3] are determined for numerical crash simulation. To investigate the validity of the calibrated ductile fracture model, axial crushing tests of hat-shaped square columns are performed for the 980 MPa grade. Numerical simulations of axial impact are also performed by ANSYS LS-DYNA [4] under the same conditions as in the experimental tests, and three-point bending tests are carried out for the 1180 MPa grade to simulate side crash deformation. Both the numerical simulations of the axial crash and the three-point bending crash show good agreement with the experimental results. The developed material model can express the excellent local elongation performance of the jetQ materials. The crash simulation with the material model shows good crash performance with a low risk of fracture during crash deformation.
Sato, Kentaro, Sakaidani, Tomohiro, Ohnishi, Yoichiro, Paton, Adrian, Roesen, Hartwig
Application of 1.7GPa Martensitic Steel in Dash Lower Cross Member to Enhance Automotive Frontal Impact Safety2025-01-82184/1/2025
The rapid growth of electric vehicles (EVs) has led to a significant increase in vehicle mass due to the integration of large and heavy battery systems. This increase in mass has raised concerns about collision energy and the associated risks, particularly in high-speed impacts. As a consequence, crashworthiness evaluations, especially front-impact regulations, have become increasingly stringent. Crash speed between the vehicle and the Mobile Progressive Deformable Barrier (MPDB) is increasing, reflecting the growing emphasis on safety in the automotive industry. Moreover, a new frontal pole crash scenario is under consideration for future regulatory standards, highlighting the continuous evolution of crash testing protocols. To ensure occupant protection and battery safety, manufacturers have traditionally used Hot Blow Forming technology for producing closed-loop dash lower cross member components. However, this process is both costly and energy-intensive, necessitating more efficient alternatives. This study explores the development of a closed-loop dash lower cross member using 1.7GPa Cold Rolled Martensitic steel, produced through roll forming and CNC bending. The research addresses critical material aspects, including comprehensive hydrogen embrittlement analysis to evaluate the material’s long-term durability and safety. Furthermore, the study focuses on the crash performance of the closed-loop cross-sectional dimensions 1.7GPa steel grades components. The findings of this study aim to contribute to the design of safer and more efficient structural components for modern EVs, meeting both regulatory requirements and industry needs.
Lee, Jongmin, Kim, Donghyun, Jang, Minho, Kim, Geunho, Seongho, Yoo, Kim, Kyu-Rae
Elevated Fracture Resistance of Q&P1180 Steel after Forming and Paint-Baking2025-01-82214/1/2025
According to several precedent studies, most of the cold-forming advanced high-strength steel (AHSS) grades can obtain reinforced yield strength from the automotive forming and paint-baking treatments without losing their fracture resistance like some aluminum alloys. Concisely, the mechanism of such behavior can be mainly attributed to the ‘Cottrell Atmospheres,’ some thermally mobilized interstitial atoms that cluster around and impede mobile dislocations during only the yielding stage of the plastic deformation but cannot continue durably enough to affect the fracture. Nevertheless, an exception, Q&P1180, was discovered from precedent studies and characterized in this work. Different from other AHSSs, this grade exhibited distinctively elevated fracture resistance and yield strength after the pre-straining and baking. Such uniqueness was speculated to be caused by 1) no soft ferrite in the microstructure and 2) the transformed fresh martensite induced by the plastic deformation being tempered-softened by the paint-baking cycle. Such two microscopic features narrowed the micro-hardness differences among the neighboring multi-phases in the deformed and baked Q&P1180 microstructures, which consequently retarded the micro-voids creation and coalescence to the macroscopic fracture. To support this speculation, a series of mechanical experiments were conducted, including various treatment conditions, stress-state, and strain-rate dependencies, on the pre-strained and baked Q&P1180 samples. As a comparison, other multi-phase AHSS grades, such as Q&P980 and DP980LCE, were also tested to indicate their lack of such behavior. Eventually, the test results characterized the consistently elevated fracture resistance of Q&P1180 under all the investigated conditions and accordingly highlighted this target material’s advantageous crashworthiness in the automotive applications.
Hu, Jun, Sun, Yeting, Thomas, Grant
Crash Performance Study on High-Speed Electric Two-Wheeler Battery Enclosure2025-28-02032/7/2025
The usage of Electric Vehicles (EVs) and the annual production rate have increased significantly over the years. This is due to the development of rechargeable electrical energy storage system (battery pack), which is the main power source for EVs. Lithium-ion batteries (LIBs) pack is predominantly used across all major vehicle categories such as 2-wheelers, 3-wheelers and light commercial vehicle. LIB is one of the high energy-dense sources of volume. However, LIBs have a challenge to pose a risk of short circuits and battery pack explosions, when exposed to damage scenarios. In the present study, the controlled crash analysis is performed for various velocities ranging from 50 kmph to 72 kmph against an obstruction directly and at an offset from the wheel, so as to mimic the real-world crash of high-speed two-wheelers. The behavior of the battery enclosure is examined through evaluating the structural integrity of the battery enclosure used in a realistic two-wheeler after crash at various colliding velocities. The study focuses on analyzing the battery enclosure for structural deformation in mild steel and comparing with a light-weight composite material. The energy absorption behavior of the enclosure is investigated through impact simulation. Mild steel is the commonly used material for battery enclosure in EVs. Strategically the design of battery enclosure for EVs can be improved by knowing the influence of materials on weight and crashworthiness. By decreasing weight and increasing the efficiency, this optimization not only enhances overall safety, but also improves the vehicle performance. As the electric vehicle landscape evolves, these findings become instrumental in shaping safer, efficient, and high-performing EVs. The results indicate that carbon fiber based composites are better compared to mild steel based on the structural integrity.
Venkatesan Sr, Aiyappan, Nelson, N Rino, Hariharan Nair, Adarsh
Basic Science and Art of Aircraft Wreckage Reconstruction, Second EditionR-58712/2/2024
Discover the Art and Science of Aircraft Wreckage Reconstruction "Provides excellent guidance on the documentation and reconstruction process and is a good field guide for anyone investigating an aircraft accident." ― Anthony T. Brickhouse, Embry-Riddle Aeronautical University Dive into the essential aspects of aircraft crash investigation with the new edition of Basic Science and Art of Aircraft Wreckage Reconstruction. Written by industry veteran Don Knutson, this comprehensive guide covers the intricacies of investigating crashes, the mindset needed for thorough investigations, and the step-by-step processes for on-scene reconstruction. Designed for practitioners, students, and enthusiasts alike, this book offers detailed references for further reading and research. Through generic yet real-life scenarios, Knutson provides valuable insights into aircraft crash investigations. Whether you're with a government aviation agency, a manufacturer, the military, an insurance company, law enforcement, or a law firm, this book is an indispensable resource. Anthony T. Brickhouse, an esteemed professor at Embry-Riddle Aeronautical University, endorses this book for its practical guidance and field applicability. His students have benefited from Knutson's blend of professional experience and personal stories. Basic Science and Art of Aircraft Wreckage Reconstruction is a must-read for anyone passionate about understanding the meticulous process of aircraft accident investigation. Enhance your knowledge and skills with this authoritative resource.
Knutson, Donald F.
Effect of Local Ductility on Crash Performance of Automotive Structures Considering Press Forming Strain of Advanced High Strength Steels2024-01-22414/9/2024
A fundamental study on the ductility of high strength steels in crash deformation is carried out to investigate the effect of the local ductility of various materials on automobile crashworthiness, considering the prestrain induced by press forming in the manufacturing process. In this study, a newly developed 980 MPa-grade steels [1], ‘jetQTM’, is investigated to clarify its advantage in term of crashworthiness in comparison with the conventional DP (Dual Phase) and TRIP steels. Quasi-static axial crushing tests are performed to evaluate the crashworthiness of the different types of steel. Based on the experimental results, the effect of the local ductility of high-strength steel on the risk of material fracture is discussed. In this paper, a new bending test method, orthogonally reverse bending, (ORB), is proposed to simulate the fracture that occurs during crash deformation considering press-forming strain. The test method is developed using a combination of the V-bending process and the tight radius bending method (based on VDA 238-100). The V-bending process is used to induce the pre-strain in the test sample, simulating the strain caused by press-forming, and the second bending process is performed to evaluate the fracture angle and local ductility of the high strength steel after the press-forming process. The proposed ORB method shows that the local ductility of TRIP steel is decreased by the press-forming due to transformation of the microstructure, while jetQ steel displays higher local ductility even after press-forming. A numerical simulation model is also developed to understand the fracture behavior in the ORB process. The simulation shows that fracture strain occurs in the local bending area with prestrain by the V-bending process. Finally, the applicability of the developed high strength steel to automobile body structures to realized light-weight body structures is discussed.
Sato, Kentaro, Sakaidani, Tomohiro, Komine, Shinsuke, Wang, Fangyi, Nakagaito, Tatsuya
A Novel Approach for Mechanical Characterization of Angle-Ply Composite Laminates2024-01-24354/9/2024
Composites made of continuous fibers generally have higher strength-to-weight ratios in fiber directions as compared to those made of discontinuous fibers. However, the latter tend to display quasi-isotropic properties which can be of advantage when directions of mechanical loading can vary. For many real-world applications such as robust design of vehicle body components for crashworthiness, impact loads are stochastic in nature both in terms of magnitude and direction. Hence, in order to realize the true potential of laminated composites with continuous fibers, instead of orthotropic laminates which are most common due to the ease of design and manufacturing, angle-ply laminates are necessary. The latter category of laminates introduce a high degree of flexibility in design options but are also simultaneously challenging in terms of mechanical characterization due to the presence of a larger number of material parameters, as compared to orthotropic laminates, with coupled normal and shear behaviors. A computationally attractive approach in large-scale numerical analysis of laminated composite structures lies in the modeling of laminates with equivalent homogeneous anisotropic properties. A practical strategy in published literature appears to be lacking on the determination of various elastic stiffness or compliance coupling coefficients for a generally-anisotropic angle-ply laminate. In the current exposition, a novel approach is demonstrated whereby using coupon specimens for tensile tests extracted at different directions with respect to a global x-direction for a square angle-ply laminate and one simple in-plane shear test, the membrane normal-shear coupling compliance parameters are determined by solving a set of linear simultaneous equations derived based on transformation of stresses and strains from global to off-axis directions. The current methodology obviates the necessity of using lateral strain gages traditionally deployed in uniaxial tests thereby making material characterization of anisotropic angle-ply laminates less time-consuming and more cost-effective.
Tanaya, Sushree, Deb, Anindya
Multi-Material and Multi-Objective Topology Optimization Considering Crashworthiness2024-01-22624/9/2024
Recently, topology optimization (TO) has seen increased usage in the automotive industry as a numerical tool, greatly enhancing the accessibility and production-readiness of optimal, lightweight solutions. By natural extension of classic single material TO (SMTO), a wealth of research has been completed in multi-material TO (MMTO), enabling simultaneous determination of material selection and existence. MMTO is effective for linear static analyses, making use of structural responses that are continuously differentiable, giving itself to efficient gradient-based optimization engines. A structural response that is inherently nonlinear and transient, thus providing difficulty to the mainstay MMTO process, is that of crashworthiness. This paper presents a multi-objective MMTO framework considering crashworthiness using the equivalent static load (ESL) method. The ESL method uses a series of linear static sub-models to approximate the transient crashworthiness model. Then, the sub-models can be optimized sequentially, using a conventional MMTO program. The limitations of the existing framework are: (1) its sole focus on intrusion minimization using displacement constraints, (2) some results have checkerboard patterns despite the use of a filter. In this paper, an improved framework aims to support the weighted sum of multiple objectives such as compliance and aggregated stress, which would affect multiple performance metrics, such as intrusion, deceleration, and energy absorption. Also, the ESL load generation method is updated to reduce checkerboarding. Firstly, the MMTO theory and ESL method are introduced. Second, the operational flow of the framework is discussed. Finally, the multi-objective solutions of an example academic model are compared using Pareto Frontiers. The optimized results show 6.4% reduction of maximum intrusion and 1.5% reduction of maximum deceleration.
Huang, Yuhao, Shi, Yifan, Morris, Zane, Teoli, Mira, Tameer, Daniel, Kim, Il Yong
Ambulance Patient Compartment Seated Occupant Excursion Zone EvaluationJ3059_202401 (Current)1/19/2024
This SAE Information Report describes the testing and reporting procedures that may be used to evaluate and document the excursion of a worker or civilian when transported in a seated and restrained position in the patient compartment of a ground ambulance when exposed to a front, side, or rear impact. Its purpose is to provide seating and occupant restraint manufacturers, ambulance builders, and end-users with testing procedures and documentation methods needed to identify head travel paths in crash loading events. This is a component level test. The seating system is tested in free space to measure maximum head travel paths. The purpose is not to identify stay out zones. Rather, the goal is to provide ambulance manufacturers with the data needed to design safer and functionally sound workstations for Emergency Medical Service workers so that workers are better able to safely perform patient care tasks in a moving ambulance. Descriptions of the test set-up, test instrumentation, photographic/video coverage, text fixture, and reporting requirements are included.
Truck Crashworthiness Committee
Damage Prediction and Crashworthiness Optimization of FOBEVs in Positive Crashes for Battery Electric Vehicles2023-01-707212/31/2023
The Mobile Progressive Deformable Barrier (MPDB) is a standardized automotive crash scenario that comprehensively evaluates the safety of battery-electric vehicles (BEVs) in a crash. In an accident, the deformation pattern of the Front of Battery Electric Vehicle (FOBEV) structure, the efficiency of energy absorption, the acceleration pulse, and the degree of intrusion into the passenger compartment combine to affect the safety of the driver and passengers. In order to simulate and calculate the damage state of FOBEV in MPDB more efficiently and to construct a collision damage dataset in the entire velocity domain, a FOBEV equivalent model is proposed. The acceleration pulses from numerical simulations and impact tests were compared to verify the model’s validity. On this basis, the prediction accuracies of the Support Vector Machine model (SVM), Gaussian Process Regression model (GPR), and BP neural network model (BP) in FOBEV collision events are compared and analyzed, and BP is taken as the most suitable model and further improved. Taking a BEV under development as an example, the application of the accident damage prediction method based on the FOBEV equivalent model in the optimal design of BEV crashworthiness is illustrated. The results show that the constructed FOBEV equivalent model exhibits high consistency in the impact test. The accuracy of the improved Tent-SSA BP model increased by 34.85%. The neural network prediction technique with multiple input parameters is used to study the crash damage of FOBEVs over the entire speed range, revealing the relationship between the parameters of FOBEVs on the crashworthiness of BEVs in highly nonlinearly varying crashes.
Liu, Ke, Liao, Yinghua, Wang, Hongrui, Xue, Xiangdong, Liu, Changzhao
Optimization of Energy Absorption and Deformation Characteristics of Aluminium Crash Box with the Effect of Groove along with a Screw2023-28-008911/10/2023
The Crash box is the mechanical component that absorbs the impact energy by axial deformation. When an accident occurs, energy absorption and deformation play a vital role in the Automobile safety aspects, and also grooves and triggers are the ones included in the crash box for axial folding and uniform deformation. Here in this research paper, the energy absorption of kinetic energy and deformation parameter is going to be compared with the crash box with the groove at different thicknesses, also the groove is added through the vertical axis along with axial crush occurs. The modeling is done in Hyper mesh 2021 and the simulation and result validation in LS Dyna. The primary goal of this research project is to increase the crash box’s efficiency and enhance the crashworthiness and the passive safety of the passenger vehicle. It is also observed that the groove plays a vital role in reducing the acceleration transmitted to the surrounding area. The box sleeve with screw run through the groove first which almost absorbs 20% of impact energy and the remaining will be absorbed during full axial folding of the crash box. The rupture will happen along with the failure of the grooves when the screw moves, thus improving the energy absorption in the crash box, this kind of screw-type crash box was also easy to replace after the collision. Further, this simulation result will be compared with the crash box without a groove. The improvisation of crashworthiness in the crumple zone of the passenger car is the primary goal of this research. The research findings provide a valuable reference for the design of crash box constructions.
SK, Vignesh, Mayakrishnan, Jaikumar, König, Peter
Study of Vehicle-Based Metrics for Assessing the Severity of Side Impacts09-12-01-000410/30/2023
A research program has been launched in Iran to develop an evaluation method for comparing the safety performance of vehicles in real-world collisions with crash test results. The goal of this research program is to flag vehicle models whose safety performance in real-world accidents does not match their crash test results. As part of this research program, a metric is needed to evaluate the severity of side impacts in crash tests and real-world accidents. In this work, several vehicle-based metrics were analyzed and calculated for a dataset of more than 500 side impact tests from the NHTSA crash test database. The correlation between the metric values and the dummy injury criteria was studied to find the most appropriate metric with the strongest correlation coefficient values with the dummy injury criteria. Delta-V and a newly created metric T K 200 Y , which is an indicator of the kinetic energy transferred to occupants in a 200 ms time interval and in the lateral direction, were found to be the most appropriate metric for assessing the crash severity of side impacts with strong correlation coefficients with head injury criteria such as HIC36 and HIC15, resultant spinal acceleration, and moderate correlation coefficients with average rib deflection and abdominal forces. Due to the need to calculate the metric based on EDR measurements, T K 200 Y was chosen as the side impact severity metric for the research program.
Sadeghipour, Emad
Crashworthiness Performance of Rear Underrun Protection Device under Simulated Car Collision15-16-03-00146/6/2023
A rear underrun protection device (RUPD) plays a fundamental role in reducing the risk of running a small car beneath the rear or the side of a heavy truck because of the difference in structure heights in the event of a vehicle collision. Even in cars with five-star safety ratings, crashing into a truck with poorly designed RUPD results in a passenger compartment intrusion (PCI) more than the maximum allowable limit as per the United States (US) American National Highway Traffic Safety Administration (NHTSA) standards Federal Motor Vehicle Safety Standard (FMVSS). In this article, mild steel was used to fabricate the new designs of RUPD. The design was analyzed using finite element (FE) analysis LS-DYNA software. Simulations of a Toyota Yaris 2010 and Ford Taurus 2001 were performed at a constant speed of 63 km/h at the time of impact. The ability to prevent severe injuries in a collision with the rear side of the truck was estimated to optimize the underrun design. The new design has achieved the goal of decreasing the head acceleration beyond the limit, which is less than 60 g. It has achieved a reduction in acceleration by 66.116% and zero PCIs even in collisions with different safety ratings cars.
Albahash, Zeid Fadel, Sharba, Mohaiman, Hasan, Bahaa Aldin Abass
Multi-Material Topology Optimization Considering Crashworthiness2023-01-00304/11/2023
There is an increasing need for lightweight structures in the transportation industry, and within these lightweight structures occupant safety is continually important to all stakeholders. Standard single and multi-material topology optimization (MMTO) techniques are effective for designing lightweight structures subjected to linear objectives and constraints but cannot consider crashworthiness. Crashworthiness must be evaluated using explicit dynamic simulation techniques, as a crash event contains geometric and material nonlinearities which cannot be captured by linear static finite element simulations. Explicit dynamic simulations prevent the calculation of sensitivity derivatives required for conventional gradient-based structural optimization strategies. This paper describes a design tool for multi-material topology optimization considering crashworthiness using the equivalent static load (ESL) method. The ESL method is used to generate linear static sub-problems which replicate the dynamic structural response of explicit dynamic crash simulations in the linear regime. The ESL sub-problems are input to a standard MMTO, optimized results from which are used as input for subsequent crash analyses to update the ESLs for additional sub-problems. The ESLs evolve as the design changes – convergence occurs when the design does not change significantly between subsequent sub-problem optimizations. The objective of this paper is to demonstrate a methodology for an efficient design tool for MMTO considering crashworthiness. Firstly, the ESL and competing methods for crashworthiness optimization are introduced and compared. Next a discussion of the tool’s operation flow as well as the sensitivity equations are presented along with two academic examples demonstrating its implementation. The design tool generates optimized multi-material designs which outperform single-material optimized designs in terms of mass by 7.5% and 17.6% in 2D and 3D models respectively when subjected to crash load cases.
Hardman, Andrew, Sirola, Tim, Huang, Yuhao, Morris, Zane, Shi, Yifan, Kim, Il Yong, Pamwar, Manish, Sangha, Balbir
Design of a Crease Pattern for Pre-Folded Origami Structures to Improve Vehicle Crashworthiness2023-01-06374/11/2023
To promote the progressive collapse of thin-walled vehicle structures and improve their energy-absorbing capabilities, designers allocate collapse initiators such as holes, grooves, humps, and creases. The use of some traditional origami patterns in pre-folded tubes has been particularly effective in this task. However, selecting the optimal origami pattern is a complex multidimensional combinatorial problem. This paper introduces a new origami pattern that triggers an extensional progressive collapse mode in a wide range of thin-walled tubes with a square cross-section. The parameters of the proposed pattern are optimized using a multi-objective Bayesian optimization algorithm to minimize the peak crushing force and maximize the mean crushing force. The crash simulations are supported by the commercial finite element solver Radioss. The optimized pre-folded origami structure depicts extensional progressive collapse under axial loads. Compared to alternative designs, results demonstrate significant improvement in crashworthiness indicators.
Chaudhari, Prathamesh, Valladares, Homero, Tovar, Andres
Crashworthiness analysis of a corkscrew rollover event2022-36-00182/10/2023
The objective of this work is to capture the final deformed shape of a vehicle after a rollover caused by a corkscrew event (ramp). With this study, it will be possible to understand the vehicle structural behavior during this event and be able to improve the vehicle safety in this specific condition. For this proposal, it will be presented a virtual methodology using available commercial CAE tools and perform a crashworthiness analysis of the desired event. The first step is to capture the dynamic event through a Multibody analysis that represents the interaction among the vehicle tire, suspension components (Springs, Dampers, Jounce Bumper, Bushings, Stabilizer Bar etc.), vehicle structural stiffness, mass, center of gravity and inertias when exposed to a corkscrew standard ramp, that initiates the rollover event. This methodology will represent with fidelity all dynamic aspects of rollover event before the vehicle touches the ground. At this point, comparison of the analysis velocities output with experimental data can be achieved. After this step, a second non-linear structural analysis in the time domain, will be performed with the vehicle positioned, with all 6 DOF matrix velocities inputted from the Multibody analysis output, at the instant of time before touching the ground. Thus, it will be possible to capture the structural behavior and deformation when the vehicle hits the ground and rolls by itself. The final structure deformed shape will be compared with physical tests results.
Tedim Terra, Rafael, Santiago, Klemer, Santos, Alex, Sobral Genaro, Piero, Capusso, Rafael
Ambulance Modular Body Evaluation - Quasi-Static Loading for Type I and Type III Modular Ambulance BodiesJ3057_202302 (Current)2/6/2023
This SAE Recommended Practice describes the test procedures for conducting quasi-static modular body strength tests for ambulance applications. Its purpose is to establish recommended test practices which standardize the procedure for Type I and Type III bodies, provide ambulance builders and end-users with testing procedures and, where appropriate, provide acceptance criteria that, to a great extent, ensures the ambulance structure meets the same performance criteria across the industry. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Load-Driven Multidisciplinary Topology Load Path Study on Car Body05-16-02-001112/14/2022
A set of multidisciplinary topology optimization (MTO) and fast validation method is discussed, which can be applied in the car body concept design stage. First, considering seven typical loading cases, optimized load path is obtained by MTO. Then an equivalent car body model is built up with new load path. In order to verify its linear and nonlinear performances quickly, original and optimized path models are established, respectively, by using macro elements. The results show that rigidity and collision performance of the optimized path are better than that of the original one. In the meantime, reduce the validation time from hours to minutes.
Zhang, Zichun, Shi, Lei
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