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

Towards Crash-Tolerant Rotorcraft Design via Topology Optimization

F-0081-2025-0232

5/20/2025

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

Test and Analysis Methodology for Validating Crashworthiness of AW609 Tiltrotor

F-0078-2022-17503

5/10/2022

ABSTRACT

Anghileri, Marco, Miller, Ryan, DiRenzo, Andrea, Waterman, Jim, Turconi, Fabrizio

Development and Analysis of Energy Absorbing Subfloor Concepts to Improve eVTOL Crashworthiness

F-0078-2022-17501

5/10/2022

ABSTRACT

Putnam, Jacob, Littell, Justin, Reaves, Mercedes, Gardner, Nathaniel

Crashworthiness Optimization of Hydraulic Excavator Cab Roof Rail and Safety Prediction: Finite Element Analysis and Experimental Validation

2021-01-09254/6/2021

Off-road trucks, tractors and earth-moving machines are at high risk of accidents involving falling objects or rollovers. Therefore, these machines need proper protective structures to protect operators. This study investigates the crashworthiness optimization of a hydraulic excavator cab roof rail based on an improved bi-directional evolutionary structural optimization (BESO) method considering two different load cases (a lateral quasi-static load and an impact load from the top of cab, respectively). In the crashworthiness optimization problem, a weighted summation of external works done by the two different load cases is treated as the objective function while the volume of design domain is treated as the constraint. A mutative weight scheme is proposed to stabilize the optimization and balance the two load cases. Finite element (FE) model is established and two prototypes are fabricated based on the optimal design. Explicit FE analysis is used to predict the performance of roll

Ma, Chao, Liu, Zhe, Duan, Yuexing, Gao, Yunkai

Incidence and Mechanism of Head, Cervical Spine, Lumbar Spine, and Lower Extremity Injuries for Occupants in Low- to Moderate-Speed Frontal Collisions

2021-01-09024/6/2021

Automotive accidents and subsequent personal injury claims incur substantial costs annually. While three-point restraint usage, dual-stage airbags, and knee bolster and side curtain airbags have become more ubiquitous and, in some cases, governmentally mandated for front seat occupants, occupant safety and injury risk assessment continue to be at the forefront of automotive innovation. In this study, we combined analyses of the National Automotive Sampling System Crashworthiness Data System (NASS-CDS; 2007-2015) and the Crash Investigation Sampling System (CISS; 2017) with data acquired from vehicle-to-vehicle crash tests conducted with instrumented anthropomorphic test device (ATD) occupants. Together, these analyses were used to compare and relate field injury rates with potential injury mechanisms in low- to moderate-speed frontal collisions. First, low- to moderate-speed (delta-V ≤ 24 km/h) frontal crash data from NASS-CDS and CISS were analyzed to estimate the rate of AIS 2+ and

Davis, M., Mkandawire, C., Brown, T., Pasquesi, S.

Crashworthiness of a Lift plus Cruise eVTOL Vehicle Design within Dynamic Loading Environments

F-0076-2020-16258

10/5/2020

To aid in the development of electric Vertical Take-off and Landing (eVTOL) technology, the National Aeronautics and Space Administration has undertaken research initiatives to evaluate and optimize design features of eVTOL aircraft. One such initiative has been to develop energy attenuating design mechanisms to improve eVTOL vehicle crashworthiness. In this study, crashworthiness design mechanisms, implemented within a six-passenger lift plus cruise (LPC) eVTOL concept vehicle, were evaluated under multi-axis dynamic loading conditions. This work builds upon crashworthiness design concepts previously optimized within a simplified vehicle-loading environment. The results of this study found the effectiveness of energy attenuating design mechanisms to be dependent on the complexity of load environment in which they were employed. An increase in off-axis loading resulted in a decrease in occupant protective capability. These results indicate the necessity for evaluating vehicle design

Putnam, Jacob, Littell, Justin

Likelihood of Spinal Disc Herniations in Occupants Involved in Real World Side Impacts

2020-01-05264/14/2020

The prevalence of spinal disc herniations in people with no spinal symptoms have been reported to increase with age; from about 20% in those below 40 years to about 30% in those above 40 years. Spinal disc herniations are usually associated with degenerative changes. Though rare, spinal disc herniations can also be caused by trauma. With an increasing number of older people on U.S. roads with a concomitant increase in the probability of getting injured in a vehicle collision, it is reasonable to expect that some of these occupants can present with clinical findings of spinal disc herniations after a side impact, and attribute these findings to the impact. In this study, we looked at the relationship between real world side impacts and the occurrence of spinal injuries, in particular disc herniations, in occupants involved in such impacts. We examined the reported occurrence of all spine injuries in side impact crashes in the National Automotive Sampling System - Crashworthiness Data

Lam, Tack, Ivarsson, B. Johan

An Innovative Approach to Component Testing Using an Impact Sled

2020-01-13314/14/2020

Historically, crash development component testing has been conducted using gravity-based vertical drop towers. The drop tower carriage is loaded to a specified weight, raised to a specific height to achieve an energy target, and dropped onto the part. This long-used approach has significant limitations with respect to achievable speed and energy, part orientation, impact angle, useable impact surface, component size, etc. With the wide variance in simulating today’s global crash scenarios, a better approach is being developed using an impact sled. The most significant advantage of this system is that there is a much higher achievable speed and energy which can be controlled with precise accuracy. This paper will provide an overview of the impact sled test system, as well as the methodology used to conduct the testing. The overview will include the challenges faced during the development of the impact sled, as well as the need for accurate and precise component fixturing methods

Kaleto, Helen, Pinelli, Alex, Briskey, Jacob P., Gizowski, John W., Reinitz, Aaron

Accident Statistical Distributions from NASS CDS - An Update

2020-01-05184/14/2020

The National Automotive Sampling System (NASS) Crashworthiness Data System (CDS) contains an abundance of field crash data. As technology advances and the database continues to grow over the years, the statistical significance of the data increases and trends can be observed. The purpose of this paper is to provide a broad-based, up-to-date, reference resource with respect to commonly sought-after crash statistics. Charts include up-to-date crash distributions by Delta-V and impact direction with corresponding injury severity rates. Rollover data is also analyzed, as well as historical trends for injury severity, belt usage, air bag availability, and the availability of vehicle safety technology.

Yaek, Jennifer L., Brown, Thomas, Goertz, Alan

The Effects of Front-Mounted Accessories on Air Bag Sensors and Crashworthiness

J2431_201910 (Current)10/9/2019

Almost all light trucks now are being manufactured with at least a driver side air bag and all will have dual air bags by 1998. The driving forces behind this feature are occupant safety, federal regulations, and competition in the industry. Along with the booming popularity of pickups and SUVs, they are commonly accessorized with a wide variety of products. Many accessories for four-wheel drives in particular are mounted on the front of the vehicle. These products include grille/brush guards, winches, snow plows, replacement bumpers, bicycle carriers, etc. Concerns have arisen over the compatibility of these accessories with the vehicle’s air bag system. The vehicle manufacturers are concerned because of their huge investment in design and crash test verification of the complete vehicle system and keen awareness of the federal regulations. The crushability of the front bumper and supporting structure are key elements in the system, so alterations to that area become logical concerns

Motor Vehicle Council

Safety Testing for AVs is Just Beginning

19AVEP03_093/1/2019

There is much work to be done in creating accurate, reliable tests for occupant crashworthiness tailored to new AV designs and seating configurations. NHTSA's plan to eventually update its New Car Assessment Program (NCAP) with new crash-test protocols is good news for both consumers and the mobility safety-systems industry. A revised NCAP will likely feature enhanced occupant safety testing as well as testing of active-safety features such as adaptive cruise control and automatic braking. It's also a positive step for autonomous vehicle (AV) developers. Studies show U.S. consumers are still resistant to the idea of self-driving cars, and such testing will provide the public with assurances that these vehicles are safe. This should serve to “warm up” consumers to the idea of a world with AVs, boosting demand and paving the way for an increasingly safer mobility future.

O'Connor, Christopher

Evaluation of Lumbar-Load Criterion Based on Test Data and Field Performance Results of the UH-60 Black Hawk Crew Seat

F-0074-2018-12739

5/14/2018

ABSTRACT The BAE Systems legacy UH-60A/L Black Hawk Crew Seat has been in serial production for almost 40 years, and has garnered a reputation for providing a high degree of crash safety to its occupants. The seat has been dynamically tested over 150 times, providing a wealth of test data that are summarized in this paper. This paper also presents a review of data from actual UH-60A/L crashes that verifies the seat's excellent performance with regards to minimizing occupant compressive spinal injuries. In addition, this paper presents a compilation of test data containing ATD lumbar-load readings. The dynamic test results are then compared to the lumbar-load limits specified in JSSG-2010-7 and the more recent Full Spectrum Crashworthiness (FSC) Criteria for Rotorcraft. This comparison shows that the seat most likely would not have passed the FSC criteria, which indicates that either the FSC lumbar-load limits are set too low, or that the dynamic test pulses do not replicate the actual

Richards, Marvin

Analyses on Mechanical Properties of the Cylindrical Double-V Micro-Structure

2018-01-01184/3/2018

The double-V micro-structures (DVMS) are a type of auxetic materials showing the negative Poisson’s ratio which can contract under compression different from the conventional materials. Due to the unique properties, it can have higher stiffness and better impact resistance with lightweight. In this paper, a cylindrical honeycomb tube based on the double-V unit cell is proposed. Firstly, the nominal Poisson’s ration and Young’s modulus in the longitudinal and circumferential directions are derived analytically. The effect of the geometry parameters of the DVMS tube on the mechanical properties is studied thoroughly. Also, the effect of the width in the radial direction on these mechanical properties is analyzed. Secondly, the finite element (FE) method is utilized to obtain the numerical solutions and verify the accuracy of the analytical solutions. The results show that there is a good agreement between the results obtained by the two methods when the width is smaller enough. With the

Gao, Qiang, wang, Yuanlong, Ma, Zheng-Dong, Zhong, Hong

Studies on Impact Performance of Gradient Lattice Structure Applied to Crash Box

2018-01-01194/3/2018

The conventional crash box with thin-walled column conceals some limitations on pedestrian protection and lightweight. The metallic NPR metamaterials designed in this study are based on re-entrant lattice structures. Re-entrant structures are known to be one main class of axenic structures that display negative Poisson’s ratio (NPR), which can be manufactured by 3D printing technology. This kind of metamaterial has good designability and can be used as the filling structure of the crash box to improve the crashworthiness of the car. This paper starts from the relations between geometric parameters of the metamaterial. Considering the deformation characteristics of the crash box, the structure were designed into some gradient types. The mechanical properties of different gradient structures under the same impact conditions were compared to find the proper gradient structures. Based on the studies, the gradient lattice structure is applied to the automobile crash box. We made some

Wu, Xian, Zhang, Shuxian, Shao, Jianwang

Investigation of the Samples Size Effects on Hybrid Surrogate Model Component Surrogates for Crashworthiness Design

2018-01-10284/3/2018

Surrogate model based design optimization has been widely adopted in automotive industry. Hybrid surrogate model with multiple component surrogates is considered to be a better choice when simulating highly non-linear responses in vehicle crashworthiness analysis. Currently, the number of component surrogates has to be decided before-hand when constructing of a hybrid surrogate model. This paper conducts a comparative study on the performances of three popular hybrid modeling methods including heuristic computation strategy, and two kinds of optimal weighted surrogates. The effects of samples size on the number of individual surrogates that should be included into the final hybrid surrogate models for crashworthiness responses are investigated. Different hybrid modeling techniques and multiple validation criteria are evaluated. Some observations and conclusions on the selection of component surrogates in hybrid surrogate modeling are given in the end.

Chen, Chong, Zhan, Zhenfei, Dong, Wenxiang, YU, Huili, Zhao, Hui

Automotive Crashworthiness Design Optimization Based on Efficient Global Optimization Method

2018-01-10294/3/2018

Finite element (FE) models are commonly used for automotive crashworthiness design. However, even with increasing speed of computers, the FE-based simulation is still too time-consuming when simulating the complex dynamic process such as vehicle crashworthiness. To improve the computational efficiency, the response surface model, as the surrogate of FE model, has been widely used for crashworthiness optimization design. Before introducing the surrogate model into the design optimization, the surrogate should satisfy the accuracy requirements. However, the bias of surrogate model is introduced inevitably. Meanwhile, it is also very difficult to decide how many samples are needed when building the high fidelity surrogate model for the system with strong nonlinearity. In order to solve the aforementioned problems, the application of a kind of surrogate optimization method called Efficient Global Optimization (EGO) is proposed to conduct the crashworthiness design optimization. Based on

Fang, Yudong, Chen, Tao, Zhan, Zhenfei, Liu, Xu, Yu, Huili, Zhao, Hui

Effects of AHSS Sheared Edge Conditions on Crash Energy Absorption in Component Bend Test

2018-01-01134/3/2018

Edge fracture of advanced high strength steels (AHSS) can occur in both the stamping process and the crash event. Fracture due to poor sheared edge conditions in the stamping process was reduced with a recently developed optimal shearing process for AHSS. Currently, the improvement in the energy absorption due to the improved edge condition during crashes performed under different loading conditions had not been closely verified. The purpose of this study is to design and build a miniature component of AHSS and a three-point bending test for investigating the influence of various conditions of the sheared edge on the energy absorption in crashes. AHSS including DP600, TRIP780, DP980 and DP1180 were selected in the study. A small channel component was developed and fabricated using DP980 to simulate key features of the B-pillar. The exposed non-constrained, as-sheared edge was subject to stretch bending forces in three-dimensional space during the three-point bending test. Two bottom

Shih, Hua-Chu, Chen, Guofei

Next Generation Smart Crashworthy Crew Seats

F-0072-2016-11415

5/17/2016

The next generation smart crashworthy crew seats will need to include design features that provide an enhanced level of crash safety while reducing the crew discomfort during long military missions. This paper presents the results from the Active Crash Protection Systems Enhancements II Program jointly funded by the U.S. Army Aviation Development Directorate - Aviation Applied Technology Directorate (ADD-AATD) and The Boeing Company under a Technology Investment Agreement. During this program a prototype crew seat design concept with actively-controlled seat energy absorbers was developed and integrated with an aircraft active crash protection system. The actively-controlled seat energy absorber technology developed enables automatic adjustment of the stroking load of the energy absorbers based on the occupant weight, available seat stroke, and the predicted crash impact conditions in order to provide an increased level of crash safety to the crew. The paper also includes results and

Bolukbasi, Akif

Development of Beam Elements for Crashworthiness Analysis of Thin-Walled Beam Structures

2016-01-04014/5/2016

In this paper, a new beam element is developed for the purpose of capturing thin-walled beam’s collapse mechanisms under dynamic load such as impact load and will be validated in the next phase. Such beam element can be used to create simplified finite element models for crashworthiness analysis and simulation and, therefore, will significantly reduce the modeling effort and computing time. The developed beam element will be implemented into LS-DYNA and validated through crashworthiness analysis and simulation. This paper introduces the approach of deriving the new element formulation.

Liu, Yucheng

Behavior of Adhesively Bonded Steel Double Hat-Section Components under Axial Quasi-Static and Impact Loading

2016-01-03954/5/2016

An attractive strategy for joining metallic as well as non-metallic substrates through adhesive bonding. This technique of joining also offers the functionality for joining dissimilar materials. However, doubts are often expressed on the ability of such joints to perform on par with other mechanical fastening methodologies such as welding, riveting, etc. In the current study, adhesively-bonded single lap shear (SLS), double lap shear (DLS) and T-peel joints are studied initially under quasi-static loading using substrates made of a grade of mild steel and an epoxy-based adhesive of a renowned make (Huntsman). Additionally, single lap shear joints comprised of a single spot weld are tested under quasi-static loading. The shear strengths of adhesively-bonded SLS joints and spot-welded SLS joints are found to be similar. An important consideration in the deployment of adhesively bonded joints in automotive body structures would be the performance of such joints under impact loading. Due

Deb, Anindya, Chou, Clifford C., Srinivas, Gunti R., Gowda, Sanketh, Kurnool, Goutham

Optimal Design of Cellular Material Systems for Crashworthiness

2016-01-13964/5/2016

This work proposes a new method to design crashworthiness structures that made of functionally graded cellular (porous) material. The proposed method consists of three stages: The first stage is to generate a conceptual design using a topology optimization algorithm so that a variable density is distributed within the structure minimizing its compliance. The second stage is to cluster the variable density using a machine-learning algorithm to reduce the dimension of the design space. The third stage is to maximize structural crashworthiness indicators (e.g., internal energy absorption) and minimize mass using a metamodel-based multi-objective genetic algorithm. The final structure is synthesized by optimally selecting cellular material phases from a predefined material library. In this work, the Hashin-Shtrikman bounds are derived for the two-phase cellular material, and the structure performances are compared to the optimized structures derived by our proposed framework. In comparison

Liu, Kai, Xu, ZongYing, Detwiler, Duane, Tovar, Andres

Crushing Analysis and Lightweight Design of Tapered Tailor Welded Hybrid Material Tubes under Oblique Impact

2016-01-04074/5/2016

The increasing demand for lightweight design of the whole vehicle has raised critical weight reduction targets for crash components such as front rails without deteriorating their crash performances. To this end the last few years have witnessed a huge growth in vehicle body structures featuring hybrid materials including steel and aluminum alloys. In this work, a type of tapered tailor-welded tube (TTWT) made of steel and aluminum alloy hybrid materials was proposed to maximize the specific energy absorption (SEA) and to minimize the peak crushing force (PCF) in an oblique crash scenario. The hybrid tube was found to be more robust than the single material tubes under oblique impacts using validated finite element (FE) models. Compared with the aluminum alloy tube and the steel tube, the hybrid tube can increase the SEA by 46.3% and 86.7%, respectively, under an impact angle of 30°. Parameter analyses were performed to reveal the influence of four geometrical variables on the

Wang, Da-Zhi, Cao, Guang-Jun, Qi, Chang, Sun, Yong, Yang, Shu, Du, Yu

Uncertainty Optimization of Thin-walled Beam Crashworthiness Based on Approximate Model with Step Encryption Technology

2016-01-04044/5/2016

Crashworthiness is one of the most important performances of vehicles, and the front rails are the main crash energy absorption parts during the frontal crashing process. In this paper, the front rail was simplified to a thin-walled beam with a cross section of single-hat which was made of steel and aluminum. And the two boards of it were connected by riveting without rivets. In order to optimize its crashworthiness, the thickness (t), radius (R) and the rivet spacing (d) were selected as three design variables, and its specific energy absorption was the objective while the average impact force was the constraint. Considering the error of manufacturing and measurements, the parameters σs and Et of the steel were selected as the uncertainty variables to improve the design reliability. The algorithm IP-GA and the approximate model-RBF (Radial Basis Function) were applied in this nonlinear uncertainty optimization. In order to improve the accuracy of the RBF model, a new step-encryption

Du, Qianqian

CFRP Crash Absorbers in Small UAV: Design and Optimization

2015-01-24619/15/2015

The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices. The specimens were produced with different auto-triggering configurations and fibers' continuity was interrupted in selected position and

Troiani, Enrico, Falaschetti, Maria Pia, Taddia, Sara, Ceruti, Alessandro

Selectable Profile Energy Absorber System for Rotorcraft Troop Seats

F-0071-2015-10139

5/5/2015

ABSTRACT A selectable profile energy absorber (SPEA) system was developed for crashworthy helicopter troop seats. This system combines information from an on-seat sensor and the aircraft data bus to tailor the energy absorber force profile not only to the weight of the occupant, but also to the predicted crash severity. The development testing was conducted using a vertical seat orientation on a drop tower under the U.S. Army Aircrew Survivability Technologies Project. This second Transport Rotorcraft Airframe Crash Testbed (TRACT 2) presented the opportunity for Safe, Inc. to independently test the SPEA system on a troop seat in an airframe undergoing a combined vertical and forward crash impact. The SPEA system is designed to use the lowest possible EA force profile considering the available stroking distance. Despite a component failure, the SPEA delivered a peak lumbar force of 572 lbf in a 50th-percentile male ATD and stroked 10 of an available 12 inches.

Desjardins, Stanley, Labun, Lance, Woodhouse, Jin, Belden, Leda

Laboratory and Field Evaluations of Textile Energy Absorbers for Crashworthy Cargo Restraints

F-0071-2015-10140

5/5/2015

ABSTRACT Improvement of cargo tie-down systems is of utmost importance to help ensure rotorcraft crew safety in the event of a hard but survivable crash or hard landing. To this end, various load-limiting, energy-absorbing devices, placed in-line with conventional tie-down hardware such as straps and chains, have been evaluated for their ability to prevent the complete failure of a tie-down and the unconstrained movement of cargo in the vicinity of nearby personnel and structure during a high-acceleration event. The current investigation aims to further this line of exploration by evaluating the performance of textile-based energy absorbing devices in well-controlled laboratory experiments using a horizontal sled and in field experiments using crash-tests of CH-46 hulks. Textile-based energy absorbers of a capacity suitable for rotorcraft tie-down systems are shown to behave as designed in both types of experiments. The devices prevented the failure of a simulated tie-down point in

Little, Eric, Bakis, Charles, Bark, Lindley, Yukish, Michael, Miller, Simon, Smith, Edward, Willis, Robert

Multi-Criteria Optimization of Foam Reinforced Thin-walled Tube Shape under Crashworthiness Requirements

2015-01-13644/14/2015

The design of aluminum foam reinforced thin-walled tubes has garnered much interest recently due to the high energy absorption capacity of these tubes. As a new kind of engineering composite material, aluminum foam can hugely increase the crashworthiness capacity without sacrificing too much weight. In this paper, axisymmetric thin-walled hollow tubes with four different kinds of cross-sections (circular, square, hexagonal and octagonal) are studied to assess their performance for crashworthiness problems. It is found that the tube with square cross-section has the best crashworthiness performance under axial impact. To seek optimal designs of square aluminum foam reinforced thin-walled tubes, a surrogate modeling technique coupled with a multi-criteria particle swarm optimization algorithm has been developed, to maximize specific energy absorption (SEA) and minimize peak crash force (PCF). To improve the accuracy of the optimization process, meta-models of SEA and PCF were constructed

Wang, Tao, Wang, LIangmo, Wang, Yuanlong, Zou, Xiaojun, Guo, Fuxiang

Simulation Fidelity Improvement of H350 Lower Tibia Indices

2015-01-05784/14/2015

Finite element dummy models have been more and more widely applied in virtual development of occupant protection systems across the automotive industry due to their predictive capabilities. H350 dyna dummy model [1] is a finite element representation of the Hybrid III male dummy [2], which is designed to represent the average of the United States adult male population. Lower extremity injuries continue to occur in front crash accidents despite increasing improvement of vehicle crashworthiness and occupant restraint system. It is therefore desirable to predict lower tibia injury numbers in front occupant simulations. Though lower tibia loading/index predictions are not studied as much as the FMVSS 208 regulated injury numbers, the tibia indices are injury criteria that need to be assessed during IIHS and Euro NCAP frontal offset occupant simulations. However during front crash simulations, it is very difficult to achieve good correlations or predictions of lower tibia loadings. A common

Li, Wei, Cheng, Yi-Pen, Furton, Lisa

Fracture Prediction for Automotive Bodies Using a Ductile Fracture Criterion and a Strain-Dependent Anisotropy Model

2015-01-05674/14/2015

In order to reduce automobile body weight and improve crashworthiness, the use of high-strength steels has increased greatly in recent years. An optimal combination of both crash safety performance and lightweight structure has been a major challenge in automobile body engineering. In this study, the Cockcroft-Latham fracture criterion was applied to predict the fracture of high-strength steels. Marciniak-type biaxial stretching tests for high-strength steels were performed to measure the material constant of the Cockcroft-Latham fracture criterion. Furthermore, in order to improve the simulation accuracy, local anisotropic parameters based on the plastic strain (strain dependent model of anisotropy) were measured using the digital image grid method and were incorporated into Hill's anisotropic yield condition by the authors. In order to confirm the validity of the Cockcroft-Latham fracture criterion, uniaxial tensile tests were performed. It was found that the accuracy of the

Takada, Kenji, Sato, Kentaro, Ma, Ninshu

Performance of CH-46 Pilot seats in NASA Full Scale Crash Test

F-0070-2014-9480

5/20/2014

This paper analyzes the performance of two CH-46 crew seats that were included in the full-scale CH-46 airframe crash test conducted on 28 August 2013 at the NASA Langley Research Center. The CH-46 crashworthy armored crew seat is an adaption of the H-53 Sea Stallion crashworthy armored crew seat and was qualified by similarity. During the crash tests, the CH-46 crew seats met the required structural performance for the test; specifically, they remained attached to the floor of the aircraft (without failing the floor structure), maintained the seat's structural integrity, and restrained the occupants. This paper compares the full-scale test performance to the qualification test performance of the seat. For the co-pilot seat, the MA-16 inertia reel was augmented with a Pre-tensioning Aircrew Restraint System (PARS), which may have resulted in some differences in the test results compared to the pilot position, most notably an improvement in the measured lumbar load. The test results

Bark, Lindley, Harris, Alex

An Investigation into the Effects of Body-borne Equipment on Occupant Injury Under Simulated Vertical Impact with Seat 'Bottom-out'

F-0070-2014-9474

5/20/2014

Over recent years, military personnel have been required to carry increasing amounts of equipment, raising the overall mass of the occupant. A crashworthy seat is designed to a specified mass range, including equipment; and only provides energy absorption protection to the occupant within its designed mass and velocity range. If the increased mass causes the impact energy to be excessive, a phenomenon called bottoming out will occur when the seat stroking mechansim is exhausted and the occupant is exposed to excessive and likely injurous loads. In this study, an 8-degree-of-freedom mass-spring-damper system was modelled to represent an occupant with body-borne equipment and simulated under a crash test. Equations to represent a fixed load energy absorption device on a seat and a spring stiffness to characterize bottoming out were developed. The model was solved using the fourth-order-Runge-Kutta method in Matlab and the results indicate that with increased equipment mass, bottoming out

Thomson, Rodney, Aggromito, Daniel, Chen, Bernard, Yan, Wenyi, Wang, John

Impact Tests and Simulations of Crashworthy Composite Structures Using Variable Load Concept

F-0070-2014-9477

5/20/2014

Composite materials are used extensively in modern helicopter structures to reduce weight. Applications include energy absorption components necessary to meet crashworthiness requirements, where composite material can offer higher Specific Energy Absorption (SEA) than traditional metallic materials. However, the constant force energy absorbers that are currently used exhibit some limitations, such as under-utilisation of the crushing stroke leading to inefficient material usage and therefore higher than necessary decelerations to the occupants in some crash scenarios. This paper describes the results of a project to develop an improved system for crashworthiness. As part of this project, a novel Variable Load Concept (VLC) has been introduced to improve the performance of the energy absorption components. The crushing force can be controlled through the radius size of trigger mechanism and the use of pressurised composite tubes. The concept and the system were developed and further