Maximum Crush Research Articles

Evaluation of crashworthiness parameters for foam-filled concentric tubes using explicit dynamics simulation

Global uncertainties have increased the crude oil prices historically and the depletion of fossil fuels are key reasons to innovate to improve fuel economy. Lightweight automotive structures are one of the prominent solutions which improve fuel economy and meet the crashworthiness requirement. Literature shows researchers are working on optimizing energy absorption and reducing the weight of the automotive structure by combining shape, size, and different categories of materials with different configurations of concentric tubes. Along with energy absorption, it is important to reduce the weight of vehicles by using lightweight materials grade. Promising lightweight materials such as foams and composites help to improve the crumple zone's crashworthiness by reducing weight and improving energy absorption. Foam improves crush stability and deformation pattern of the structure during impact loading. This research paper discusses a finite element analysis method using Ansys Explicit solver and its result validation with an experimental UTM compression test with some boundary conditions. This validated CAE model is used to predict the result of a quasi-static test, foam-filled tubes with various shapes and materials such as AA6063-T4 and Polyurethane (PU) foam and wall thicknesses (i.e., 1.5 mm and 1.7 mm) were evaluated in this paper. The quasi-static test's experimental and simulation findings were more than 80 % correlated. From CAE analysis of various combination foam-filled hexagonal structure with a 1.7 mm wall thickness showed better specific energy absorption (SEA): 10.69 KJ/Kg, lower maximum crush force (Fmax): 51.01 KN, and highest crush force efficiency (CFE): 67 % as compared to other structures. A velocity scaling method was used to improve the computational efficiency of the solver by increasing the time increment. Velocity scaling has a negligible effect on the accuracy of results which meet the result of quasi-static compression test performed on UTM machine.

Vehicle crashworthiness performance in frontal impact: Mathematical model using elastic pendulum

Vehicle occupant injuries due to collisions cause many fatalities every year. Safe vehicle design plays a critical role in averting serious injuries to occupants and vulnerable road users in the event of a crash. In this paper we study a full frontal vehicle crash against a rigid barrier introducing a Lumped Parameter Model (LPM) inspired by the elastic pendulum motion. The model uses polar coordinates to simplify the problem and the governing equations have been defined using Lagrangian formulation. The Simulink model has been validated against Finite Element (FE) data demonstrating good correlation with pitching angle and maximum crush of the vehicle. These parameters are crucial for designing vehicles which efficiently protect occupants.

Optimization and crush characteristic of foam-filled fender subjected to transverse loads

This research analyzed the energy absorption characteristics and crashworthiness design of a regular ship fender structure with varying geometric dimensions such as single foam fender (SFF), empty double fender (EDF), and foam-filled double fender (FDF). Furthermore, the research determined specific energy absorption (SEA) and maximum crushing force efficiency (CFE) of foam-filled fender. To calculate the crash responses, non-linear finite element analysis is carried using the explicit ABAQUS and the result compared to relevant reference. Therefore, this research aims to optimize the crashworthiness indicators of aluminum foam-filled fenders subjected to transverse loads. Multi-objective using NSGA II is applied to obtain the Pareto optimal solutions for maximum Crush Force Efficiency (CFE) and maximum Specific Energy Absorption (SEA). From the optimization result, it is found that FDF has the best performance, however it is recommended to change the conventional fender design.

Performance Evaluation of a Banana Pseudostem Chopper

The method of returning banana (Musa nana) pseudostems to the field can effectively maintain and improve the level of organic matter in the soil. In this article, we show that a small vertical-type banana pseudostem chopper can be used in banana plantations that do not need to be replanted. The aim of this study was to investigate the relationship among the blade type, cutting force, and cutting power. The effects of the blade roll angles, pitch angles, and feeding angles on the crushing qualification rate and crushing efficiency were obtained by comparing the decomposition characteristics of a banana pseudostem before and after crushing. The results showed that the arc-shaped blade exhibited the smallest cutting force and cutting power consumption. The maximum crush qualification rate and crush efficiency were obtained when the roll angle was 12°, the pitch angle was −5°, and the feeding angle was 5°. The weight reduction rate and average decomposition rate of the crushed pseudostem were 2.73 and 3.61 times greater than those of natural decomposition, respectively. The results can be used as a reference for the design and optimization of banana pseudostem choppers.

Compression performance and mechanism of superimposed sine-wave structures fabricated by selective laser melting

A novel superimposed sine-wave (SSW) structure was designed and fabricated by selective laser melting (SLM) in this work. The energy absorption performance, deformation modes, and fracture mechanism of heat-treated SSW components under compression were studied. The formability was analyzed and the results showed that the SLM fabricated SSW components possessed nearly dense microstructure and smooth surface morphology. The numerical simulation model was established to show the stress distribution and deformation mechanism during compression, and the fracture morphologies of SSW components were investigated. Experimental results indicated that the SSW components exhibited a maximum crush force efficiency (CFE) of 73.06%, which was higher than most reported energy absorption structures. As the height of sinusoid 1 (H1) increased, the energy absorption (EA) and specific energy absorption (SEA) gradually increased to 37.73 J and 8.45 J/g, respectively. Simulation results revealed that the secondary trough had a large deformation during the compression process, which greatly enhanced the load uniformity of the structure. Fracture mode of SSW components was ductile fracture due to the post heat treatment. The SSW structures had the potential to be used in aerospace, protective armor, and automotive industries.

Injury risk curves in far-side lateral motor vehicle crashes by AIS level, body region and injury code

Objective The objective of this study was to develop injury risk curves as a function of change in vehicle velocity for occupants in far-side lateral motor vehicle crashes (MVCs) by AIS level, body region, and specific AIS codes that commonly occur in this crash mode. Methods The National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) years 2000–2015 database was queried, resulting in 4,495 non-weighted far-side crashes. For each case, occupant age, sex, and the following metadata were collected: vehicle model year, vehicle body type, lateral delta-v, normalized PDOF, multiple impacts, belt use, seat position, object contacted, striking vehicle body type, maximum crush extent and side airbag deployment. Multivariable logistic regression was used to develop risk curves for AIS 2+ through 5+ injuries, AIS 2+ injuries by body region (head, thorax, lower extremity), and for each of the 10 most frequent far-side AIS 2+ injuries. Significant covariates were determined by backwards elimination (p < 0.05). The full dataset and a subsampled dataset of only cases with side airbag deployment were used to develop risk curves. Results For AIS 2+ through 5+ injury, greater delta-V was associated with greater injury risk (OR’s: 2.48–3.66 per 11.9 kph increase) and belt use was associated with lower risk (OR’s: 0.04–0.36 compared to unbelted). Multiple impacts were significant predictors of increased AIS 3+, 4+ and 5+ injury risk (OR’s: 2.56, 2.27 and 2.83 compared to single impact). For AIS 2+ body region injuries, lateral delta-V and maximum CDC extent were positively associated with increased head, thorax and lower extremity injury risk while belt use was associated with lower risk. Increased lateral delta-v, unbelted status, and greater maximum CDC extent frequently increased injury risk for the most common far-side injuries. Side airbag deployment was not a significant covariate for the injury risk models. Conclusions The resulting risk models expand upon previous literature gaps to provide a more comprehensive view of contributors to injury risk for occupants in far-side MVCs. This study yields risk curves based on the latest available NASS-CDS data.

Crashworthiness performance of concentric structures with different cross-sectional shapes under multiple loading conditions

This paper evaluates the crashworthiness performance of concentric structures with different numbers of tubes (i.e. one to five) and cross-sectional shapes (i.e. hexagon, octagon, decagon and circle) under the multiple loadings of θ = 0, 10, 20 and 30°. An experimentally validated finite element model generated in LS-DYNA is employed to calculate the crashworthiness parameters including the specific energy absorption, maximum crush force and crush force efficiency. A total of 20 concentric structures are analyzed to explore the effects of number of tubes and cross-sectional shapes on the crushing performance. A multi-criteria decision-making method known as TOPSIS is also used to compare and rank the concentric structures in terms of crushing performance. Based on the results, the hexagonal structure including two tubes and octagonal, decagonal and circular structures including three tubes demonstrate the best results among their corresponding cross-sectional shapes. These structures show 9, 39, 38 and 39% higher specific energy absorption compared to their corresponding single tubal cases, respectively. However, in comparison to single tubal cases, they generate 4, 57, 57 and 58% higher maximum crush force, respectively. As such, the values for the improvement of the crush force efficiency are 3, 26, 25 and 21%, respectively. Furthermore, the decagonal structure including three tubes provides the highest energy absorbing characteristics as compared with all the other structures studied in this research. Meanwhile, taking into account all the multiple loading conditions, this structure shows 50% higher specific energy absorption than the hexagonal structure including single tube (as the weakest structure).

Crushing analysis and multi-objective optimization of different length bi-thin walled cylindrical structures under axial impact loading

ABSTRACTThis article attempts to increase the crashworthiness characteristics of energy absorbers. It is found that the effect of the bi-tubular arrangement on the energy absorption and peak force is nonlinear. This nonlinearity is somewhat related to friction but is mostly related to the changing of buckling modes. Therefore, it is possible to reach higher Specific Absorbed Energy (SAE) in the bi-tubular case than with two tubes since the weight is the same in both arrangements while the energy absorption is higher in the bi-tubular case. To exploit this, multi-objective optimization of bi-thin walled cylindrical aluminium tubes under axial impact loading is performed. The absorbed energy and the SAE are considered as the objective functions while the maximum crush load is regarded as a constraint. Finally, the optimal dimensions of tubes are found in order to maximize the SAE and energy absorption for a specified maximum crushing force.

Foam filling options for crashworthiness optimization of thin-walled multi-tubular circular columns

There is an increasing trend in using aluminum foam-filled columns in crash management systems due to their light weight in automotive industry. The main goal of this study is to optimize the crashworthiness of aluminum foam-filled thin-walled multi-tubular circular columns under quasi-static loading. The existing studies in the literature considered only lateral foam filling (the foam lateral dimension is variable and the foam height is equal to the column height). In the present study, we considered both lateral and axial foam filling and compared the performances of these two options. In optimization, the column thicknesses, taper angle, foam density, and foam height/diameter are considered as design variables. The quasi-static responses of the columns are determined through explicit dynamic Finite Element Analysis (FEA) using LS-DYNA software, and validated with quasi-static tests conducted in our facilities. Response surface based crashworthiness optimization of the columns for maximum Crush Force Efficiency (CFE) and maximum Specific Energy Absorption (SEA) is performed. It is found that lateral foam filling is superior to axial foam filling in terms of both CFE and SEA maximization. The maximum CFE obtained through lateral foam filling is 19% larger than the maximum CFE obtained through axial foam filling. Similarly, the maximum SEA obtained through lateral foam filling is 6% larger than the maximum SEA obtained through axial foam filling. For both CFE and SEA maximization, the columns should be tri-tubular type and have a large thickness and a taper angle. To attain the maximum CFE, foam should be designed with large density and medium foam diameter. However, foam plays an adverse role in maximization of SEA because of its weight. The increase in energy absorption obtained by using foam does not compensate the additional weight introduced by the foam.

Numerical study for identification of influence of energy absorption and frontal crush for vehicle crashworthiness

According to the statistics it has been seen that everyday nearly 400 people are killed due to road accidents. Due to this it has become an important concern to concentrate on the safety of the passengers which can be done by improving the crashworthiness of the vehicle. During the impact, a large amount of energy is released which if not absorbed, will be transmitted to the passenger compartment. For the safety of the passenger this energy has to be absorbed. Front rail is one of the main energy absorbing components in the vehicle front structure. When it comes to the structure and material of the part or component of the vehicle that is to be designed for crash, it is done based on three parameters: Specific Energy of Absorption, Mass of the front rail and maximum crush force. In this work, we are considering different internal geometries with different materials to increase the energy absorbing capacity of the front rail. Based on the extensive analysis carried aluminium seizes to be the opt material for frontal crash.

Crashworthiness study and optimisation of free inversion foam-filled tubes under dynamic loading

ABSTRACTThe inversion processes of the proposed tubes under axial impact are simulated to investigate the detailed features of crushing process by using the explicit finite element FE code LS-DYNA. To validate the FE results, a new theoretical relation is developed . The validated FE model was then used for the parametric studies, to investigate the maximum crush distance and the effect of impact mass and the geometry parameters (i.e. wall thickness, foam density) on response of free inversion tubes under different strain rate loadings. Finally, a search algorithm combining Latin hypercube design (LHD) points and genetic algorithm is developed to carry out the multiobjective optimisation through the geometrical average method. The optimal design of the foam-filled free inversion tube demonstrates a significant improvement in the crashworthiness over the benchmark designs with the same loading conditions.

The effect of motorcycle helmet fit on estimating head impact kinematics from residual liner crush

Proper helmet fit is important for optimizing head protection during an impact, yet many motorcyclists wear helmets that do not properly fit their heads. The goals of this study are i) to quantify how a mismatch in headform size and motorcycle helmet size affects headform peak acceleration and head injury criteria (HIC), and ii) to determine if peak acceleration, HIC, and impact speed can be estimated from the foam liner’s maximum residual crush depth or residual crush volume. Shorty-style helmets (4 sizes of a single model) were tested on instrumented headforms (4 sizes) during linear impacts between 2.0 and 10.5m/s to the forehead region. Helmets were CT scanned to quantify residual crush depth and volume. Separate linear regression models were used to quantify how the response variables (peak acceleration (g), HIC, and impact speed (m/s)) were related to the predictor variables (maximum crush depth (mm), crush volume (cm3), and the difference in circumference between the helmet and headform (cm)). Overall, we found that increasingly oversized helmets reduced peak headform acceleration and HIC for a given impact speed for maximum residual crush depths less than 7.9mm and residual crush volume less than 40cm3. Below these levels of residual crush, we found that peak headform acceleration, HIC, and impact speed can be estimated from a helmet’s residual crush. Above these crush thresholds, large variations in headform kinematics are present, possibly related to densification of the foam liner during the impact.

Crashworthiness research and optimisation design of sandwich multi-cell conical tube under axial impact

A novel sandwich multi-cell conical (SMC) tube was designed and analysed by using Abaqus/Explicit. The performances of three different conical tubes, i.e., ordinary conical tube, four cell conical tube and SMC tube, were compared. The variables that influence the performances of crashworthiness were investigated. Then, according to this investigation the optimisation goal and design variables are determined. Optimal Latin hypercube design method was adopted to define the sample points for establishing and evaluating the surrogate model. Finally, a numerical simulation on the sample points was performed by utilising Abaqus/Explicit. The surrogate model with three different indicators, i.e., the specific energy absorption, the maximum crush force, and the crush force efficiency, was constructed by using kriging method and the simulation results. The accuracy of surrogate model was evaluated with four distinct methods. Finally, the non-dominated sorting genetic algorithm-II was utilised to optimise the multi-objective problem.

Crashworthiness research and optimisation design of sandwich multi-cell conical tube under axial impact

A novel sandwich multi-cell conical (SMC) tube was designed and analysed by using Abaqus/Explicit. The performances of three different conical tubes, i.e., ordinary conical tube, four cell conical tube and SMC tube, were compared. The variables that influence the performances of crashworthiness were investigated. Then, according to this investigation the optimisation goal and design variables are determined. Optimal Latin hypercube design method was adopted to define the sample points for establishing and evaluating the surrogate model. Finally, a numerical simulation on the sample points was performed by utilising Abaqus/Explicit. The surrogate model with three different indicators, i.e., the specific energy absorption, the maximum crush force, and the crush force efficiency, was constructed by using kriging method and the simulation results. The accuracy of surrogate model was evaluated with four distinct methods. Finally, the non-dominated sorting genetic algorithm-II was utilised to optimise the multi-objective problem.

Dynamic Response and Residual Helmet Liner Crush Using Cadaver Heads and Standard Headforms.

Biomechanical headforms are used for helmet certification testing and reconstructing helmeted head impacts; however, their biofidelity and direct applicability to human head and helmet responses remain unclear. Dynamic responses of cadaver heads and three headforms and residual foam liner deformations were compared during motorcycle helmet impacts. Instrumented, helmeted heads/headforms were dropped onto the forehead region against an instrumented flat anvil at 75, 150, and 195J. Helmets were CT scanned to quantify maximum liner crush depth and crush volume. General linear models were used to quantify the effect of head type and impact energy on linear acceleration, head injury criterion (HIC), force, maximum liner crush depth, and liner crush volume and regression models were used to quantify the relationship between acceleration and both maximum crush depth and crush volume. The cadaver heads generated larger peak accelerations than all three headforms, larger HICs than the International Organization for Standardization (ISO), larger forces than the Hybrid III and ISO, larger maximum crush depth than the ISO, and larger crush volumes than the DOT. These significant differences between the cadaver heads and headforms need to be accounted for when attempting to estimate an impact exposure using a helmet's residual crush depth or volume.

Finite Element Model Prediction of Pulmonary Contusion in Vehicle-to-Vehicle Simulations of Real-World Crashes

Objective: Pulmonary contusion (PC) is a common chest injury following motor vehicle crash (MVC). Because this injury has an inflammatory component, studying PC in living subjects is essential. Medical and vehicle data from the Crash Injury Research and Engineering Network (CIREN) database were utilized to examine pulmonary contusion in case occupants with known crash parameters.Method: The selected CIREN cases were simulated with vehicle finite element models (FEMs) with the Total HUman Model for Safety (THUMS) version 4 as the occupant. To match the CIREN crash parameters, vehicle simulations were iteratively improved to optimize maximum crush location and depth. Fifteen cases were successfully modeled with the simulated maximum crush matching the CIREN crush to within 10%. Following the simulations, stress and strain metrics for the elements within the lungs were calculated. These injury metrics were compared to patient imaging data to determine the best finite element predictor of pulmonary contusion.Results: When the thresholds were evaluated using volumetric criteria, first principal strain was the metric with the least variation in the FEM prediction of PC.Conclusions: A preliminary threshold for maximum crush was calculated to predict a clinically significant volume of pulmonary contusion.

Injury prediction in a side impact crash using human body model simulation

BackgroundImproved understanding of the occupant loading conditions in real world crashes is critical for injury prevention and new vehicle design. The purpose of this study was to develop a robust methodology to reconstruct injuries sustained in real world crashes using vehicle and human body finite element models. MethodsA real world near-side impact crash was selected from the Crash Injury Research and Engineering Network (CIREN) database. An average sedan was struck at approximately the B-pillar with a 290 degree principal direction of force by a lightweight pickup truck, resulting in a maximum crush of 45cm and a crash reconstruction derived Delta-V of 28kph. The belted 73-year-old midsized female driver sustained severe thoracic injuries, serious brain injuries, moderate abdominal injuries, and no pelvic injury. Vehicle finite element models were selected to reconstruct the crash. The bullet vehicle parameters were heuristically optimized to match the crush profile of the simulated struck vehicle and the case vehicle. The Total Human Model for Safety (THUMS) midsized male finite element model of the human body was used to represent the case occupant and reconstruct her injuries using the head injury criterion (HIC), half deflection, thoracic trauma index (TTI), and pelvic force to predict injury risk. A variation study was conducted to evaluate the robustness of the injury predictions by varying the bullet vehicle parameters. ResultsThe THUMS thoracic injury metrics resulted in a calculated risk exceeding 90% for AIS3+ injuries and 70% risk of AIS4+ injuries, consistent with her thoracic injury outcome. The THUMS model predicted seven rib fractures compared to the case occupant's 11 rib fractures, which are both AIS3 injuries. The pelvic injury risk for AIS2+ and AIS3+ injuries were 37% and 2.6%, respectively, consistent with the absence of pelvic injury. The THUMS injury prediction metrics were most sensitive to bullet vehicle location. The maximum 95% confidence interval width for the mean injury metrics was only 5% demonstrating high confidence in the THUMS injury prediction. ConclusionsThis study demonstrates a variation study methodology in which human body models can be reliably used to robustly predict injury probability consistent with real world crash injury outcome.

Similarity scoring methodology for comparing real-world cases to crash test standards

A National Automotive Sampling System–Crashworthiness Data System (NASS–CDS) based Similarity Scoring Methodology (SSM) is presented for the quantitative comparison of real-world crashes to crash tests. Using NASS–CDS 2000–2008, five categorical and five continuous crash, vehicle and occupant parameters were utilised for frontal and side impacts. Mahalanobis metric results revealed that 1% of frontal and 23% of side NASS–CDS cases scored received similarity scores of <0.14 demonstrating greater similarity to standard crash tests. These included 20,334 frontal and 442,511 side impact case occupants (weighted). On average, the best scores occurred for NASS–CDS cases compared to FMVSS 214 side crash tests. The majority of real-world crashes had lower delta-Vs and maximum crush than associated crash tests. The results will aid in the study of occupant safety and vehicle crashworthiness by helping researchers identify population groups to study real-world injuries versus the injury risk predicted by anthropomorphic test devices.

Packaging Mechanical Properties of Composite Paperboard

The effects of different kinds of pulp on structure and packaging mechanical properties of composite board. The results show that in order to obtain maximum ring crush strength of composite board, in the forming process of composite board, wheat straw pulp is used as outer layer because it has strong bonding force and higher fibrosis degree. Waste news paper pulp is used as inner layer because its cost is low.

자동차 정면충돌에서 자동차 영구 변형량에 따른 승객 상해 추정

The estimation of occupant injury risk at crash accident is one of the most important assessments for the vehicle crashworthiness performance. The design of safety devices such as occupant restraining system also depend on the kinematics of occupant and its injury risk. The real world in-depth accident investigation provides detailed and realistic information of vehicle damage and occupant injury as well as the accident conditions. This paper introduces a statistical analysis of NASS/CDS database and domestic accident data to correlate speed change, vehicle damage extend, and occupant injury at frontal crash. The maximum crush extend shows a linear relationship with the effective impact speed. The injury risks of the occupant with and without restraining were also respectively quantified with the crush extend. This result can be effectively used for the emergent rescue of crash victims with automatic crash notification system.