Lateral Impact Research Articles

Importance of impact boundary conditions and pre-crash arm position for the prediction of thoracic response to pendulum, side sled, and near side vehicle impacts

Two contemporary finite element Human Body Models (HBMs) were subjected to five lateral impact scenarios to investigate the sensitivity of thorax response to impact scenario and pre-crash arm position. The greatest increase in chest compression (UW-HBM: +140%, GHBMC-HBM: +100%) and Viscous Criterion (UW-HBM: +467%, GHBMC-HBM: +245%) occurred when the arm was aligned with the thorax in a full vehicle impact, moderate change for sled impacts, and only a minor change in response for pendulum impacts. This study highlights the importance of including full vehicle impact boundary conditions in parametric studies of occupant response in side impacts and assessing side-impact protection.

Numerical simulation and analysis of midfacial impacts and traumatic brain injuries.

BackgroundsThe maxillofacial region is the exposed part of the human body and is susceptible to injury due to the limited protective equipment. Due to anatomic proximity of the maxillofacial skeleton and cranium, the force can be transmitted directly to the brain in case of maxillofacial impact, maxillofacial injuries are often accompanied with craniocerebral trauma. Therefore, it is necessary to study the biomechanical response mechanism of trauma to improve prevention of traumatic brain injury (TBI).MethodsTo investigate the biomechanical mechanism between the two injuries, a finite element (FE) head model including skull, midfacial bones and detailed anatomical intracranial features was successfully developed based on CT/MRI data. The model was validated by comparing it with one classical cadaver experiment. During the simulations, three different load forces were used to simulate common causes of injury seen in the clinic including boxing-type impact injury and car accident-type impact injury, and four locations on the model were considered as common injury sites in the midface.ResultsTwelve common impact scenarios were reproduced by FE simulation successfully. Simulations showed that there was a linear relationship between the severity of TBI and the collision energy. The location of TBI was directly related to the location of the impact site, and a lateral impact was more injurious to the brain than an anterior-posterior impact. The relative movement between the skull and brain could cause physical damage to the brain. The study indicated that the midfacial bones acted as a structure capable of absorbing energy and protecting the brain from impact.ConclusionsThis biomechanical information may assist surgeons better understand and diagnose brain injuries accompanied by midfacial fractures.

WITHDRAWN: Analysis of structure on slopes infill shear wall at different locations

Abstract A comparative study on seismic resistance of a structure on slopes with infill shear wall carried out on residential working by considering the gravity lords and lateral loads as Earthquake loads and Wind loads incorporating the shear walls to reduce the lateral power impact on structural individuals. The structure situated in sloping territories are especially progressively inclined to seismic condition in contrast with the structures that are arranged in level ground. Because of the inclining ground the section stature varies as short and long segments. Henceforth the huge measure of parallel power is pulled in by short segment because of its higher solidness. It prompts extreme harm to structure and causes loss of human life and property. Subsequently to expand the seismic presentation of expanding on inclining ground the shear dividers assume exceptionally essential job. Subsequently in this investigation the endeavor is made to break down the skyscraper structures on normal and inclining ground having and not having shear dividers. A G + 15 skyscraper having with various ground slopes varying from as 0°, 10°, 20° and 30° having shear walls and including shear walls at center four sides, at corner and giving total outside dividers shear divider have been considered for the examination. The structure proposed is designed by Limit State Method according to IS: 456-2000, the wind load analysis according to IS: 875-(part-3) 2015 and seismic loads according to IS: 1893(part-1) 2016. Shear divider examination as indicated by IS: 13920-2016.

Lateral Impact Resilient double concave Friction Pendulum (LIR-DCFP) bearing: Formulation, parametric study of the slider and three-dimensional numerical example

Seismic isolation has been one of the best alternatives in protecting structures, being frictional isolators one of the most used devices in constructing isolation systems. Under extreme seismic inputs, the impact between the inner slider and the restraining rims of the plates could occur. This internal impact has been indicated as one of the main contributors to the failure of frictional pendulum bearings. This paper presents a new type of frictional device, the Lateral Impact Resilient double concave Friction Pendulum (LIR-DCFP) bearing. This device has an improved inner slider that enhances the dynamic behavior if the lateral capacity of the isolator is overcome. The three-dimensional formulation of the LIR-DCFP bearing is presented and proposed to perform dynamics analyzes. A parametric analysis was performed to evaluate the influence of the geometry of the inner slider. Finally, a comparative three-dimensional analysis between the dynamic response of a structure isolated using LIR-DCFP bearings and double concave Friction Pendulum (DCFP) bearings is presented. Important reductions in the base shear, inter-story drifts, and absolute accelerations are achieved using LIR-DCFP bearings.

Pelvic Injury Risk Curves for the Military Populations From Lateral Impact.

Current methods for transporting military troops include nonstandard seating orientations, which may result in novel injuries because of different types/directions of loading impact. The objective of this study is to develop pelvic injury risk curves (IRCs) under lateral impacts from human cadaver tests using survival analysis for application to military populations. Published data from lateral impacts applied to whole-body cadaver specimens were analyzed. Forces were treated as response variables. Demographics and body mass index (BMI) were covariates. Injury risk curves were developed for forces without covariates, for males, females, 83 kg body mass, and 25 kg/m2 BMI. Mean and ± 95% confidence interval IRCs, normalized confidence interval sizes at discrete risk levels, and quality indices were obtained for each metric-covariate combination curve. Mean age, stature, total body mass, and BMI were 70.1 ± 8.6 years, 1.67 ± 0.1 m, 67.0 ± 14.4 kg, and 23.9 ± 3.97 kg/m2, respectively. For a total body mass of 83 kg, peak forces at 10%, 25%, and 50% probability levels were 5.7 kN, 7.4 kN, and 9.6 kN, respectively. For males, peak forces at the 10%, 25%, and 50% probability levels were 4.8 kN, 6.4 kN, and 8.4 kN, respectively. For females, peak forces at the 10%, 25%, and 50% probability levels were 3.0 kN, 4.0 kN, and 5.2 kN, respectively. Other data and risk curves are given. The IRCs developed in this study can be used as injury criteria for the crashworthiness of future generation military vehicles. The introduction of BMI, sex, and total body mass as covariates quantified their contributions. These IRCs can be used with finite element models to assess and predict injury in impact environments to advance Soldier safety. Manikins specific to relevant military anthropometry may be designed and/or evaluated with the present IRCs to assess and mitigate musculoskeletal injuries associated with this posture and impact direction.

Built-up battened steel columns under impact loading: Experimental and numerical analysis

In this work, experimental and numerical investigations are employed to examine the performance of the built-up battened steel columns under lateral impact load. The columns consist of four equal angle sections connected using batten plates. Drop-hammer impact tests were performed on six specimens, in which 3 impact energies were employed. Modes of failure, impact force-time histories and permanent deformations were obtained in the test. Subsequently, finite element (FE) models were established using ABAQUS, in which the strain-rate effects of steel material and initial global imperfections were considered. In addition, the validated FE models were utilized to analyze the whole dynamic response and investigate the influences of key parameters, including the impact energy, impact location, boundary condition and axial-load level etc., on the impact behaviour. A further discussion on the non-dimensional parameter of the energy absorption capacity (EAC) was conducted to qualify the behaviour of the built-up battened steel columns under impact load.

Development of a detailed human neck finite element model and injury risk curves under lateral impact

Advanced neck finite element modeling and development of neck injury criteria are important for the design of optimal neck protection systems in automotive and other environments. They are also important in virtual tests. The objectives of the present study were to develop a detailed finite element model (FEM) of the human neck and couple it to the existing head model, validate the model with kinematic data from legacy human volunteer and human cadaver impact datasets, and derive lateral impact neck injury risk curves using survival analysis from the upper and lower neck forces and moments. The detailed model represented the anatomy of a young adult mid-size male. It included all the cervical and first thoracic vertebrae, intervening discs, upper and lower spinal ligaments, bilateral facet joints, and passive musculature. Material properties were obtained from literature. Frontal, oblique, and lateral impacts to the distal end of the model was applied based on human volunteer and human cadaver experimental data. Corridor and cross-correlation methods were used for validation. The CORrelation and Analysis (CORA) score was used for objective assessments. Forces and moments were obtained at the occipital condyles (OC) and T1, and parametric survival analysis was used to derive injury risk curves to define human neck injury tolerance to lateral impact. The Brier Score Metric (BSM) was used to determine the hierarchical sequence among the injury metrics. The CORA scores for the lateral, frontal, and oblique impact loading conditions were 0.80, 0.91, and 0.87, respectively, for human volunteer data, and the mean score was 0.7 for human cadaver lateral impacts. Injury risk curves along with ±95% confidence intervals are given for all the four biomechanical metrics. The OC shear force was the optimal metric based on the BSM. A force of 1.5 kN was associated with the 50% probability level of AIS3+ neck injury. As a first step, the presented risk curves serve as human tolerance criteria under lateral impact, hitherto not available in published literatures, and they can be used in virtual testing and advancing restraint systems for improving human safety.

Dynamic responses of reinforced ultra-high performance concrete members under low-velocity lateral impact

This paper presents a combined experimental and numerical study on the low-velocity lateral impact behavior of reinforced ultra-high performance concrete (UHPC) members. Firstly, a total of eleven steel bar reinforced UHPC and two reinforced normal strength concrete (NSC) control specimens with the identical dimensions (300 mm × 300 mm × 2200 mm) were prepared and tested under drop hammer impact. By examining the influences of impact energy (16.66–33.32 kJ) and the axial force (140–1400 kN) on the dynamic damage and responses of specimens, the outstanding impact resistance of UHPC members is validated and assessed quantitatively. Besides, the presence of axial force can effectively improve the lateral impact resistance of the UHPC members, particularly the recovery of deformation. Secondly, based on the commercial finite element (FE) program LS-DYNA, a FE model was established to predict the impact behavior of UHPC members. The Continuous Surface Cap (CSC) model for NSC was adopted, and the corresponding model parameters for UHPC were calibrated based on a series of test data, i.e., static compressive and direct tensile tests, dynamic compressive and tensile tests, triaxial compressive tests, and hydrostatic tests. Furthermore, the generation method of CSC model parameters for UHPC was proposed, which was fully validated by comparing with the present and existing low-velocity impact test data on reinforced UHPC and UHPC filled steel tube (UHPC-FST) members.

Experimental and numerical studies on square steel-reinforced concrete-filled steel tubular (SRCFST) members subjected to lateral impact

Steel-reinforced concrete-filled steel tubular (SRCFST) structures were proposed in recent years and have been employed in engineering practices. To date, the existing studies mainly focused on the behaviours of SRCFST structural members under static or seismic load. Only very limited studies of the SRCFST structural members subjected to impact load, which might cause severe damage and even structural collapse, can be found in literature. In this study, experimental and numerical studies on square SRCFST specimens under lateral impact load are conducted. A total of eighteen square SRCFST specimens are fabricated and tested via a drop hammer impact device. Various parameters (i.e. impact velocity, boundary condition, impact direction, cross-section of steel profile and axial load level) are considered to evaluate their effects on impact responses of square SRCFST members. The damage modes, impact forces, mid-span displacement responses and energy absorption capacities of the tested specimens are extracted from testing data and analysed. Furthermore, by using the software ABAQUS, numerical model is established and validated with the testing results. With the validated numerical models, the damage evolution, sectional stress and energy distribution of the structure with different parameters and impacting scenarios are evaluated. The impact behaviours of square SRCFST and concrete-filled steel tubular (CFST) members are also compared and discussed.

Experimental Study on the Impact Resistance of Closed‐Cell Aluminum Foam Protective Materials to RC Piers under Lateral Impact

In this study, the lateral impact tests of six RC piers which were protected by closed‐cell aluminum foam (CCAF) were carried out by making use of an ultrahigh drop hammer horizontal impact test system. The protective effects of CCAF with different densities on the piers were then analyzed. The data regarding the piers’ impact force, displacement, reinforcement strain, and crack and damage development were mainly collected during the experimental testing processes. The results indicated that, when the impact energy was less than 7258 J and the density of the CCAF was 0.45 g/cm3, the cumulative impact force and displacements of the piers decreased by 67% and 35%, respectively. Therefore, it was considered that the CCAF with a density of 0.45 g/cm3 had displayed the best protective effects at that stage. It was also observed that when the impact energy was greater than 7258 J and the density of the CCAF was 0.55 g/cm3, the cumulative impact force and displacements of the piers decreased by 25% and 18%, respectively. Therefore, the CCAF with a density of 0.55 g/cm3 had displayed the best protective effects at that stage. Furthermore, under the conditions of constant accumulative impact energy, the protective effects of CCAF on the piers were observed to be weakened if it entered the densification stage too early and high‐yield platforms were formed due to the density levels becoming too high. However, it was found that reasonable density and thickness increases could effectively delay the entry of CCAF into the densification stage, which effectively reduced the shearing effects which occurred when the impact speeds were too high, thereby preventing the shear failure of the piers.

System configuration of instrumented half-scaled armoured vehicle to enhance handling performance due to lateral firing impact

Yaw disturbance rejection control (YDRC) is developed to improve the handling performance of armoured vehicle due firing impact. Therefore, a complete system configuration of instrumented half-scaled armoured vehicle is required to interface the YDRC algorithm with integrated measurement and control (IMC) data acquisition system, inertial measurement unit (IMU) and rotary encoder sensors. By using this configuration, the impact of firing test has been evaluated at maximum firing angle of 90° and vehicle speed of 40 km/h. Based on the actual testing, the handling response of the armoured vehicle in terms of yaw rate and angle, lateral displacement and acceleration has been improved compare to passive armoured vehicle up to 45% of reduction.

System configuration of instrumented half-scaled armoured vehicle to enhance handling performance due to lateral firing impact

Yaw disturbance rejection control (YDRC) is developed to improve the handling performance of armoured vehicle due firing impact. Therefore, a complete system configuration of instrumented half-scaled armoured vehicle is required to interface the YDRC algorithm with integrated measurement and control (IMC) data acquisition system, inertial measurement unit (IMU) and rotary encoder sensors. By using this configuration, the impact of firing test has been evaluated at maximum firing angle of 90° and vehicle speed of 40 km/h. Based on the actual testing, the handling response of the armoured vehicle in terms of yaw rate and angle, lateral displacement and acceleration has been improved compare to passive armoured vehicle up to 45% of reduction.

Axial Compression Performance of Reinforced Concrete Columns after Lateral Impact Load

Axial Compression Performance of Reinforced Concrete Columns after Lateral Impact Load

Development of structural testing equipment for impact and complex loading

ABSTRACT This paper summarizes the author’s work of developing various impact testing equipment and equipment for simulating complex earthquake loading for structural research. The equipment include large diameter split Hopkinson pressure bars (SHPB), large-scale drop-weight testing equipment, field-test facility of truck collisions and multi-axes seismic loading equipment. Several types of building and bridge components were tested under axial or lateral impact loads, simulating vehicular impact actions, sudden collapse and blasts. For vehicular impact action, a procedure of establishing simulative equivalent vehicular frame is proposed, making the vehicular loading tests much easier. Fundamental tests on concrete cylinders and confined concrete cylinders under high-strain rate impacts were also carried using the large-diameter equipment. Large to full-scale reinforced concrete or steel structures were also studied experimentally, using the developed equipment.

Test on residual ultimate strength of pultruded concrete-filled GFRP tubular short columns after lateral impact

This paper presented the experimental investigations and numerical analyses on the compressive behavior of pultruded concrete-filled GFRP tubular (CFGT) short columns after lateral impact. Taking the thickness of GFRP tube, concrete compressive strength, impact height, and impact location as influential factors, 117 CFGT short columns were tested under axial compression, including 108 specimens after lateral impact and 9 specimens without impact. Tear-up and Tear-up included local buckling were two main failure characteristics of specimens under axial compression. Test results indicated that the increase of thickness of GFRP tube remarkably enhanced the residual ultimate strength of specimens subjected to lateral impact. The impact height exerted negative effects on the residual ultimate strength and axial stiffness of the CFGT short columns. The residual ultimate strength of the specimens decreased significantly as the impact height increased, especially for the thin-walled specimens. However, the impact location only showed a limited influence on the residual ultimate strength of CFGT short columns. According to the experimental results and theoretical analyses, the design formulas were proposed to estimate the residual ultimate strength of CFGT short columns after lateral impact.

Dynamic plastic behavior of single and nested rings under lateral impact

This paper aims to investigate the dynamic plastic behavior of single and nested circular rings traditionally used as energy absorbers. The response characteristics of these structures are experimentally and numerically determined when they are subjected to high rate lateral impacts. It should be emphasized that a gas gun is employed in order to conduct experimental tests in which a load cell is utilized to measure the force-time response at the distal end. Furthermore, the finite element software LS-Dyna is employed to obtain numerical results in which the Johnson-Cook constitutive equation is used to take into account the strain rate and hardening effects. It is revealed that employed single rings as energy absorbers are absorbing input energies while transmitting small amounts of forces particularly peak loads to protected specimens or occupants. Moreover, it is determined that circular rings having smaller thicknesses and greater inner diameters are much more efficient energy absorbers. However, it is found that single rings have low energy absorption capacity leading to high peak loads for high input energies. It is shown in the presented paper that nested rings can be used as suitablealternatives since they can absorb much more energy and transmit much fewer forces compared to single rings.

Effect of graphene on the methyl methacrylate beam under lateral low-velocity impact

PurposeThis paper aims to present the potential of using aligned single-layer graphene sheets to reinforce the methyl methacrylate cantilever beam in low-velocity impact problem.Design/methodology/approachThe Halpin–Tsai law is applied to compute the mechanical properties of isotropic polymer beam reinforced by aligned graphene sheet. Using both longitudinal and lateral displacements in composite beam, all components of the stress and strain fields are written. The equations of motion are derived by applying energy method, generalized Lagrange equations and Ritz method.FindingsThe analytical formulation accuracy is corroborated by comparing the present results with those available in the literature. Numerical examples indicate that the contact duration is decreased with increasing of graphene volume fraction, whereas the values of peak contact force, shear strain and shear stress at peak contact force tend to be vice versa. Also, among the results, shear stress at the peak contact force has the most effect with graphene volume fraction changes.Originality/valueThis research fulfils an identified need to investigate how graphene-reinforced beam behavior subjected to low-velocity impact can be enabled.

Dynamic behavior of SRC columns with built-in cross-shaped steels subjected to lateral impact

This paper presents an investigation on the dynamic behavior of SRC columns with built-in cross-shaped steels under impact load. Seven 1/2 scaled SRC specimens were subjected to low-speed impact by a gravity drop hammer test system. Three main parameters, including the lateral impact height, the axial compression ratios and the stirrup spacing, were considered in the response analysis of the specimens. The failure mode, deformation, the absorbed energy of columns, as well as impact loads are discussed. The results are mainly characterized by bending-shear failure, meanwhile specimens can maintain an acceptable integrity. More than 33% of the input impact energy is dissipated, which demonstrates its excellent impact resistance. As the impact height increases, the flexural cracks and shear cracks observed on the surface of specimens were denser and wider. The recorded time-history of impact force and mid-span displacement confirmed the three stages of relative movement between the hammer and the column. Additionally, the displacements had a notable delay compared to the rapid changes observed in the measured impact load. The deflection of the mid-span did not exceed 5.90mm while the impact load reached peak value. The impact resistance of the specimen can be improved by proper design for stirrup ratios and increasing the axial load. However, the cracking and spalling of the concrete cover at the impact point was obvious with the increasing in stiffness.

Behavior of CFRP-UHPFRC-steel double skin tubular columns against low-velocity impact

In this study, a total of six specimens were prepared and tested, and the dynamic response and damage mechanism of carbon fiber reinforced polymer (CFRP)-ultra-high performance fiber-reinforced concrete (UHPFRC)-steel double skin tubular (DST) columns against low-velocity impact were investigated. The effects of CFRP, impact energy, hollowness ratio and infilled concrete on the behavior of CFRP-UHPFRC-steel double skin tubular columns against low-velocity impact were studied. Moreover, the software LS-DYNA was used to simulate the CFRP-UHPFRC-steel DST columns against low-velocity impact, and the feasibility of the model was verified by comparing the simulation and experimental results. Based on the verified model, the damage evolution of the infilled concrete was investigated. Afterwards, parametric analyses were carried out using the validated finite element model. The results show that increasing the steel ratio and decreasing the slenderness ratio can improve the lateral stiffness and the lateral impact resistance of specimens. When the impact position is closer to the fixed end of the specimen, the global deflection decreases. Only binding CFRP within a certain range at the impact region can also have a good restraint effect on the specimen and can enhance the lateral impact resistance of the specimen. Furthermore, indenters with different shapes have different effects on the behavior of specimens against low-velocity impact.

Experimental Research on the Mechanical Performance of the Bolted Rock under Lateral Impact Load: Effect of Prestress, Body Material, and Anchorage Style

In order to reveal the impact mechanical properties and their key influencing factors of the bolted rock under the lateral impact load, through the lateral drop hammer impact test, the time-history curve of impact force, axial force of the bolt, and surface strain of the sample under different combination types of influencing factors is obtained, and the whole process of deformation and failure of the bolted rock is recorded. The test results show that the material of the bolt has a significant influence on the impact force and axial force of the bolt. There is a positive correlation between bolt strength and impact peak and impact attenuation slope and a negative correlation between bolt strength and impact action time. The effect of prestress on the impact resistance of the bolted rock was also evaluated by the test which suggested that prestress of the bolt can significantly reduce both impact time and bolt axial force of the bolted rock but has limited effect on the impact force. It was also found that the time-history curve of the impact force of anchoring rock mass had significant difference with full-length anchoring and nonanchoring. Compared with the nonanchoring bolt, the full-length anchored rock mass has a larger impact peak and shorter action time, which means that the impact resistance of the full-length bolted rock has a certain degree of weakening. Through scientific research, determining the reasonable bolt material, prestress value, and anchorage style can improve the impact resistance of the sample.