Impact Loading Conditions Research Articles

Investigation on vehicle occupant dummy applicability for under-foot impact loading conditions

PurposeUnder-foot impact loadings can cause serious lower limb injuries in many activities, such as automobile collisions and underbody explosions to military vehicles. The present study aims to compare the biomechanical responses of the mainstream vehicle occupant dummies with the human body lower limb model and analyze their robustness and applicability for assessing lower limb injury risk in under-foot impact loading environments. MethodsThe Hybrid III model, the test device for human occupant restraint (THOR) model, and a hybrid human body model with the human active lower limb model were adopted for under-foot impact analysis regarding different impact velocities and initial lower limb postures. ResultsThe results show that the 2 dummy models have larger peak tibial axial force and higher sensitivity to the impact velocities and initial postures than the human lower limb model. In particular, the Hybrid III dummy model presented extremely larger peak tibial axial forces than the human lower limb model. In the case of minimal difference in tibial axial force, Hybrid III's tibial axial force (7.5 KN) is still 312.5% that of human active lower limb's (2.4 KN). Even with closer peak tibial axial force values, the biomechanical response curve shapes of the THOR model show significant differences from the human lower limb model. ConclusionBased on the present results, the Hybrid III dummy cannot be used to evaluate the lower limb injury risk in under-foot loading environments. In contrast, potential improvement in ankle biofidelity and related soft tissues of the THOR dummy can be implemented in the future for better applicability.

Design Optimisation of Metastructure Configuration for Lithium-Ion Battery Protection Using Machine Learning Methodology

The market for electric vehicles (EVs) has been growing in popularity, and by 2027, it is predicted that the market valuation will reach $869 billion. To support the growth of EVs in public road safety, advances in battery safety research for EV application should achieve low-cost, lightweight, and high safety protection. In this research, the development of a lightweight, crashworthy battery protection system using an excellent energy absorption capability is carried out. The lightweight structure was developed by using metastructure constructions with an arrangement of repeated lattice cellular structures. Three metastructure configurations (bi-stable, star-shaped, double-U) with their geometrical variables (thickness, inner spacing, cell stack) and material types (stainless steel, aluminium, and carbon steel) were evaluated until the maximum Specific Energy Absorptions (SEA) value was attained. The Finite Element Method (FEM) is utilised to simulate the mechanics of impact and calculate the optimum SEA of the various designs using machine learning methodology. Latin Hypercube Sampling (LHS) was used to derive the design variation by dividing the variables into 100 samples. The machine learning optimisation method utilises the Artificial Neural Networks (ANN) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to forecast the design that produces maximum SEA. The optimum control variables are star-shaped cells consisting of one vertical unit cell using aluminium material with a cross-section thickness of 2.9 mm. The optimum design increased the SEA by 5577% compared to the baseline design. The accuracy of the machine learning prediction is also verified using numerical simulation with a 2.83% error. Four different sandwich structure configurations are then constructed using the optimal geometry for prismatic battery protection subjected to ground impact loading conditions. An optimum configuration of 6×4×1 core cells arrangement results in a maximum displacement of 7.33 mm for the prismatic battery in the ground impact simulation, which is still less than the deformation threshold for prismatic battery safety of 10.423 mm. It is shown that the lightweight metastructure is very efficient for prismatic battery protection subjected to ground impact loading conditions.

Experimental and numerical investigation of multi-layered honeycomb sandwich composites for impact mechanics applications

This project aims to investigate the design of a multi-layered sandwich composite and its performance under impact loading conditions. An experimental and numerical assessment was performed to conclude the effect of increasing the layers of sandwich panels. Three specimens of four different sandwich panel configurations were manufactured to be tested. The skin of the sandwich panels comprises a twill carbon-reinforced epoxy resin, whereas the core consists of a 2D Nomex honeycomb core. The panels are then subjected to transverse impact loading to investigate their impact behaviour. These experimental results are then used to verify numerical models constructed in LS-Dyna. The models of the honeycomb-reinforced sandwich panels are investigated using MAT-054 and MAT-142 material cards in LS-Dyna to find the most economical computational approach. Finally, the energy absorption characteristics calculated during the experimental and numerical work are used to conclude the multi-layered sandwich composite's performance and provide design recommendations. The findings suggest that by increasing the core and shell numbers through the thickness of the panel, the specific energy absorption capability will increase.

A State-of-the-Art Review on Computational Modeling of Dynamic Soil–Structure Interaction in Crash Test Simulations

The use of nonlinear, large-deformation, dynamic finite element analysis (FEA) has become a cornerstone in crash test simulations, playing a pivotal role in evaluating the safety performance of critical civil infrastructures, including soil-embedded vehicle barrier systems. This review paper offers a detailed examination of numerical modeling methodologies employed for simulating dynamic soil–structure interactions in crash test simulations, with a particular focus on dynamic impact pile–soil interaction. This interaction is a critical determinant in assessing the effectiveness of soil-embedded barrier systems during vehicular impacts. Our extensive review methodically categorizes and critically evaluates four prevalent modeling methodologies: the lumped parameter method, the subgrade reaction method, the modified subgrade reaction approach, and the direct or mesh-based continuum method. We explore each methodology’s underlying philosophy, strengths, and shortcomings in accurately simulating the dynamic interaction between soil and piles under impact loading. This technical review aims to provide a thorough understanding of the critical and distinctive aspects of modeling soil’s dynamic responses under impact loading conditions. Moreover, this paper is envisioned to serve as a foundational reference for future research endeavors, steering the advancement of innovative simulation techniques for tackling the dynamic impact soil–structure interaction problem.

Impact response of SCS sandwich slabs with ultra-high performance concrete: Failure mechanism and influence of shear connector configuration

In the typical steel-concrete-steel (SCS) sandwich structure, the normal-strength concrete core fills the external steel skeleton. This paper describes a program of drop-weight tests and finite element investigations on reduced-scale SCS sandwich slabs with ultra-high performance concrete (UHPC) core material as a novel protective layer construction. Test results demonstrated that the steel-ultra-high performance concrete-steel (SUHPCS) sandwich slabs were adequate for forming enhanced dynamic resistance through the high strength of UHPC and tensile stiffening membrane of the steel skins. Also, this construction was found to perform a highly ductile behavior and sustain obvious bulges without penetration through the whole slab. Precise finite element models for sandwich slabs under impact loading conditions were established and the simulated time histories were verified against the test data. Furthermore, a parametric study of sandwich slabs designed with different configurations of shear connectors was subjected to a spherical hammer weighing 540 kg dropping from the height of 5 m. The simulation results showed that the failure mode of SUHPCS sandwich slab changed with various degrees of composite interaction. Moreover, a theoretical methodology was proposed to classify the failure mode involving stiffness, flexural and punching resistances. SUHPCS sandwich slabs with a reasonable layout of shear connectors were found to provide a means for effective energy absorption against severe impact attacks.

Improved mechanical properties of environmentally friendly jute fibre reinforced metal laminate sandwich composite through enhanced interface

Natural plant based fibres are being increasingly used in sustainable fibre reinforced composite applications in order to meet the demand of using environmentally friendly materials for composites. Fibre metal laminates (FMLs) are used in aerospace, automobile, marine and civil engineering applications, due to their excellent mechanical behaviors compared to traditional metals and their alloys. This study describes a novel fabrication of jute fibre reinforced aluminum metal laminates, using different jute fibre architectures (plain and twill fabric structures), wherein jute fibres were used in the skins and aluminum in the core layers. Jute fibres and aluminum sheets were chemically treated to enhance the compatibility and interfacial bonding at fibre-metals-matrix interfaces. FMLs were manufactured by hot pressing technique, after the application of wet lay-up process for the resin impregnation and they were further tested under tensile, flexural and impact loading conditions. While comparing results, the twill architecture showed improved tensile and flexural properties compared to plain fabric based FMLs. Chemical treatments on twill jute fibres and metal sheets further exceptionally enhanced the flexural properties (151 MPa flexural strength and 21.3 GPa modulus and they were increased by 186.5 % and 722.7 % respectively compared to the untreated jute fibre counterparts) of the laminates due to a significant improvement in the adhesion between the jute fibre and aluminum sheet after alkali treatment applied. Therefore, with these enhanced properties, jute based FML laminates can be used as sustainable composite materials in many structural applications.

Experimental study on the impact resistance of bamboo scrimber beams under impact loading

Drop-weight impact tests were conducted on bamboo scrimber beams to assess their resistance to dynamic stress. The study focused on investigating the influence of impact orientation, velocity, and cross-section size on failure modes and mechanical behavior. A comparison of data between dynamic impact and static load conditions consistently showed failure via cracking at the bottom of the beam. The severity of damage increased with impact velocity. Beams with greater stiffness exhibited less deformation, increased peak force, and reduced deflection. The energy absorption increased nonlinearly with impact speed, eventually stabilizing at higher velocities. Additionally, it was observed that increased stiffness led to a slight reduction in energy dissipation. The study also demonstrated the presence of inertia effects in bamboo beams during impact and proposed a design approach for enhancing impact resilience. Furthermore, a predictive model was developed to estimate the maximum deflection under dynamic conditions.

High-fidelity prediction and temperature-rise mechanism for low-velocity impact of triaxially braided composites

An elastoplastic mechanical-thermal constitutive model was integrated into the development of a mesoscale finite element model. This model aimed to analyze the temperature rise phenomenon and failure behavior of composites under impact loading conditions. Triaxially braided carbon/epoxy composite specimens were subjected to low-velocity impact using a drop weight tester, and the temperature variations within the specimens were monitored using an infrared camera. The numerical predictions successfully reproduced the observed failure modes and accurately captured the temperature distribution. A numerical study was performed to explore the main factors of temperature rise, indicating that plastic work of pure matrix and fracture transformed energy of fiber tow are the primary sources of temperature rise. The transverse specimen was found to exhibit superior energy absorption capacity under high-energy impacts.

The effects of graphene oxide addition on low velocity impact performance of aramid fiber reinforced epoxy composites

AbstractIn this study, the impact of incorporating graphene oxide (GO) nanoparticles into the matrix of aramid fiber reinforced polymer (AFRP) composites was investigated. The GO nanoparticles were dispersed in the AFRP matrix at three different weight percentages: 0.1%, 0.3%, and 0.5%. The fabrication of the GO dispersed AFRP nanocomposites was achieved using the vacuum assisted resin infusion molding (VARIM) method, and the AFRP plates were cut using a water jet. The sectioned specimens of the fabricated nanocomposites were subjected to low velocity impact tests. The effects of introducing GO nanoparticles at different percentages were evaluated by analyzing the contact force, deflection, maximum absorbed energy versus time and contact force versus deflection curves. Finally, the key parameters of low velocity impact, including contact force, deflection, and maximum absorbed energy, were compared for the different fabricated AFRP nanocomposites. Based on the results, the AFRP composite with 0.3 wt.% of GO nanoparticles exhibited the best performance under low velocity impact loading conditions. However, the agglomeration of nanoparticles became a significant challenge when higher percentages of GO nanoparticles were added to the composite structure. The findings highlight the importance of determining the optimal percentage of nano materials for incorporation into composite structures.

Recent trend in stretchable composite sensors for wearable robot applications

Conventional sensors can detect the various physical and chemical changes that occur during deformation and the states of materials with a high accuracy. However, almost all existing sensors are bulky and stiff, making them highly susceptible to failure when used in large deformation-compliant structures. By contrast, despite their relatively-low resolution and accuracy, the demand for flexible and stretchable sensors used in detecting human motion and vital signs has drastically increased. There are several types of stretchable sensors that contain functional materials such as carbon nanotubes (CNTs). These stretchable sensors have different working principles and applications based on the attributes of their core components. Several electrical signals are used in the measurement of the different physical parameters such as the electrical resistance and capacitance. Triboelectric nanogeneration or voltage signals that can be identified under contact or impact loading conditions are employed in some measurement methods. Additionally, an array of microstructures with a special shape that is directly related to movement and deformation detection, as well as conductive nano-particles that are elaborately aligned along a certain direction for specific sensor applications, are used in the other methods. In this study, a review of the recently-developed high-performance stretchable sensors made from functional materials using new sensing mechanisms for wearable robot applications is provided.

Quantifying the effect of cerebral atrophy on head injury risk in elderly individuals: Insights from computational biomechanics and experimental analysis of bridging veins

The objective of this study was to quantitatively investigate the relationship between cerebral atrophy and the risk of injury in elderly individuals. To achieve this, a sophisticated computational biomechanics approach utilizing finite element analysis was employed to simulate the mechanical behavior of the brain and skull under various conditions. In addition, particular emphasis was placed on understanding the role of cerebral bridging veins (BVs) and their mechanical properties at different ages in the occurrence of head injuries.Head models representing healthy brains and five atrophy models were developed based on imaging data. After validation, the models underwent the identical impact loading conditions to enable the simulation of brain damage. The resulting outcomes of the models with brain atrophy were then compared to the results obtained from the healthy model, allowing for a comparative analysis. Simulations showed increased relative displacement with worsening brain atrophy, particularly in the frontal and occipital regions. Compared to the healthy brain model, relative displacement increased by 2.36 %–9.21 % in the atrophy models, indicating an elevated risk of injury. In severe brain atrophy (FEM 6), the strain reached 83.59 % in local model simulations, leading to damage and rupture of cerebral BVs in both young and elderly individuals. Mechanical tests on cerebral BVs demonstrated a negative correlation between age and ultimate force, stress, and strain, suggesting increased susceptibility to damage with age. An observed sharp decline of approximately 50 % in ultimate stress and 35 % in ultimate strain was noted as age increased. We implemented a 50 % reduction in the intensity of head impact forces; nevertheless, vascular damage continues to manifest in the elderly population. To establish a truly safe zone, it is imperative to further decrease the intensity of the impact. This investigation represents a significant step forward in our understanding of the complex interplay between cerebral atrophy, the mechanical properties of BVs at different age, and the risk of head injury in the elderly. Through continued research in this field, we can strive to improve the quality of care, enhance prevention strategies, and ultimately enhance the well-being and safety of the elderly population.

Benchtop impaction device replicates cadaveric loading conditions of the transforaminal lumbar interbody fusion (TLIF) procedure

Background contextLumbar spine disc pathologies often necessitate removal of the intervertebral disc and implantation of a lumbar interbody fusion (LIF) device. Herein, the objective was to measure use condition forces while simulating intra-operative loading conditions of transforaminal lumbar interbody fusion (TLIF) procedures. MethodsIn this work, we developed a transferable method to measure impact forces in a cadaveric intra-operative setting and designed a drop weight benchtop device equipped with force and displacement sensors to replicate cadaveric impact conditions, including number of strikes required for interbody device insertion, peak force, initial slope of the impact waveform, impact duration, and area under the force-time curve (impulse). Following cadaveric testing, a benchtop biomechanical study varying interbody device height, drop height, and drop weight was performed to evaluate the utility of the benchtop device to replicate impact loading conditions which occurred in the cadaveric model. ResultsSeveral benchtop test groups replicated the cadaver group in number of strikes required for device insertion. The average cadaveric peak force, 13.03 kN, was replicated by three benchtop groups: 12 mm device height, 60 cm drop height, 0.75 lb drop weight; 12 mm device height, 60 cm drop height, 1.0 lb drop weight; and 14 mm device height, 60 cm drop height, 0.50 lb drop weight. The initial slope of the impact waveform was replicated best by 12 mm devices. Both the impact duration and impulse were lower in all benchtop groups than in cadaver testing. ConclusionsThis work validated the outfitting of an impact force sensor onto an interbody device insertion instrument as a reproducible, quantifiable method for collecting impact loading data in a cadaveric model. This benchtop device and methodology will aid in testing interbody devices relative to anticipated use conditions, enhance interbody device designs, and accelerate surgical technique refinement.

Bending analysis of glass fiber reinforced epoxy composites/copper-clad laminates for multi-layer printed circuit boards

Printed circuit board (PCB) is the most important part of any electronic device which is made of copper-clad laminate and glass fiber-reinforced composites. Since the ply orientation of fiber-reinforced composites and lamina thickness have a significant influence on the mechanical properties of the whole composite laminate it is necessary to investigate the effects of ply orientation and lamina thickness on the bending properties of PCB so that they can be manufactured to meet the service requirements. In this work, the bending properties of PCB were investigated for seven different ply orientations of glass fiber-reinforced composite laminas and for eight different thickness combinations (for a constant laminate thickness) of glass fiber-reinforced composite lamina and copper-clad laminate. A commercially available finite element analysis software (Abaqus) was used to simulate a three-point bending test of PCBs and the simulation results were validated using experimental results. It is found that the bending stiffness is maximum for the cross-ply laminate. The introduction of angle ply improves the maximum von-Mises stress of the PCB with an insignificant cost of bending stiffness (less than 5% reduction). It is found that the bending stiffness and the maximum von-Mises stress of the PCB can be regulated through the variation of thickness of the constituent lamina. The laminate stiffness can be increased by increasing the thickness of stiffer laminas or by placing the stiffer laminas towards the surface of the laminate. The outcome of this research would provide a comprehensive understanding of the bending characteristics of the multi-layered PCBs which can be directly utilized by the PCB manufacturers. However, the effects of ply orientation and lamina thickness variation on the behavior of the PCBs subject to temperature variation, impact loading, vibration, and other conditions that might affect the service life of the PCBs should be investigated.

Damage analysis and energy absorption capacity of hollow square steel tubes subjected to conical hammer impact

ABSTRACT Steel tubes find widespread applications in various structural elements, including load-bearing columns, stair guardrails, and security bollards, due to their high strength and durability. However, these structures are susceptible to damage under impact loading conditions. While prior studies have focused on drop hammer shapes like rectangles, wedges, cylinders, and hemispheres, research on the impact of a conical-shaped hammer on square and rectangular steel tubes remains limited. Therefore, this study aims to analyse the damage resulting from the impact of a conical-shaped hammer on square steel tubes using nonlinear Finite Element Analysis (FEA) software ABAQUS/Explicit. The investigation explores the effects of various parameters, including tube geometry, impact location, impactor mass, and impact height, on tube deformation and fracture behaviour of tube. Through comprehensive analysis, it was observed that the impacted site exhibited punching failure accompanied by inward bending of the tube, while outward buckling occurred at the support. The energy absorption process was examined, and the effect of the aforementioned parameters on the energy absorption capacity (EAC) was assessed. The findings indicate that the thickness of the steel tube has the most significant impact on the impact force and EAC. Additionally, the deflection of the tube was primarily influenced by the length of the hollow section.

EVALUASI JEMBATAN BOKS GIRDER BETON SETELAH MENGALAMI BENTURAN KECELAKAAN KAPAL

A bridge is a structure that connects two places separated by an obstacle. These obstacles are in the form of rivers, seas, ravines, or gaps between buildings. One of them is the sea, where planning must consider the free height of the bridge to prevent being struck by ship traffic. Preventive efforts, however, were not expected due to the sea level exceeding the planned high conditions, which led to an accident where a ship struck the bridge. This condition causes the bridge to experience transverse deformation due to the impact load conditions on the bridge in the transverse direction. The odd behaviour of the bridge, particularly in the compression and tension sections, required a brief further examination. The incident of the ship crashing into the bridge was taken from the case study of the 6 Barelang Bridge, where the concrete box girder type bridge was affected by LBW APCs. Australian One Ship in 2012. Bridge behaviour was reviewed using non-linear geometric analysis, and the static impact load estimated with the AASHTO Method. The condition of the model is then compared with historical data on bridge damage for structural modelling verification.

Effect of Prior Boriding on Microstructure and Mechanical Properties of Nanobainitic X37CrMoV5-1 Hot-Work Tool Steel.

The influence of prior pack boriding on the microstructure and properties of nanobainitised X37CrMoV5-1 hot-work tool steel was investigated in the present work. Pack boriding was conducted at 950 °C for 4 h. Nanobainitising consisted of two-step isothermal quenching at 320 °C for 1 h, followed by annealing at 260 °C for 18 h. A combination of boriding with nanobainitising constituted a new hybrid treatment. The obtained material exhibited a hard borided layer (up to 1822 ± 226 HV0.05) and a strong (rupture strength 1233 ± 41 MPa) nanobainitic core. However, the presence of a borided layer decreased mechanical properties under tensile and impact load conditions (total elongation decreased by 95% and impact toughness by 92%). Compared with borided and conventionally quenched and tempered steel, the hybrid-treated material retained higher plasticity (total elongation higher by 80%) and higher impact toughness (higher by 21%). It was found that the boriding led to the redistribution of carbon and silicon atoms between the borided layer and substrate, which could influence bainitic transformation in the transition zone. Furthermore, the thermal cycle in the boriding process also influenced the phase transformations during subsequent nanobainitising.

Mitigation of spall fracture by evolving porosity

Ductile materials subject to impact loading conditions can undergo spall fracture when an incoming compressive stress wave reflects off interfaces and free surfaces as a tensile stress wave. Experimental observations suggest that in ductile materials, spall fracture is driven by the evolution of porosity. However, the presence of initial porosity in ductile materials also introduces plastic compressibility, which can attenuate the incoming compressive stress wave and, as a result, reduce the amplitude of the reflected tensile stress wave. This, in turn, can mitigate or delay spall fracture. In this work, we report on finite deformation finite element calculations that analyze the response of porous ductile materials subjected to impact loading conditions. Two sets of calculations are carried out, in the first set the material contains initial porosity values ranging from 0% to 5% while in the second set the material also undergoes stress-controlled porosity nucleation. Both sets of calculations are carried out for a wide range of imposed impact velocities. Our results show that porosity in ductile materials can, under certain circumstances, mitigate spall fracture by attenuating stress waves. Results correlating the effects of impact velocity, initial porosity, and porosity nucleation on spall fracture are presented and the underlying mechanisms are discussed.

Influence of different combinations of impact mass and velocity with identical kinetic energy or momentum on the impact response of RC piles

Marine engineering structures may be subjected to various levels of vessel collisions, causing different degrees of damage to the RC piles. However, the influence of different combinations of impact mass and velocity under the same initial kinetic energy or momentum on the impact behavior of RC piles has not been explored. A numerical investigation of the impact responses of RC pile structures (including plumb piles and inclined pile groups) considering the material strain rate effect is carried out using the software ABAQUS/Explicit in this paper. Parametric studies are conducted based on the validated finite element models of RC piles subjected to horizontal impact. The internal force distributions, as well as the effect of the impact kinetic energy and the momentum (including different combinations of impact mass and initial velocity) on the impact response of RC piles, are discussed. The results indicate that the development path of the bending moment‒overall structural displacement curves in the plastic hinge regions of RC piles are almost identical under both impact and static loading conditions. Compared to momentum, the impact response of RC piles is insensitive to the variation of impact kinetic energy with different combinations of impact mass and velocity. Therefore, the impact kinetic energy is more suitable for evaluating the structural deformation of RC piles after impact. Finally, a performance-based impact-resistance design framework for RC piles is proposed.

Numerical Simulation Study on the Blast Loading Performance of Reactive Fragment

In this paper, numerical simulation is used to study the buffer layer material, thickness and structure on the reactive fragment load and its action time under blast impact loading conditions. The results show that the buffer layer can significantly reduce the peak pressure of the detonation wave acting on the reactive fragment and prolong the action time; the buffering capacity of different buffer materials is different; for the same material, the buffering capacity is proportional to the material thickness; compared with a single layer of buffer layer, the buffer layer with the same thickness and composite structure has a stronger capacity.

Electric Go-Kart

Abstract: This project presents the design and analysis of an electric motor-powered Go-kart. The main aim of this project is to reduce the usage of organic fuel powered vehicles and to design a vehicle which works efficiently in the emerging electric vehicle sector. In order to maintain the speed levels of theGo-kart, seamless decision was made in motor selection. Alternate materials have been applied in the Go- kart to reduce both static and dynamic forces in pursuance of improving the efficiency and performance ofthe Go-kart. The main focus of the frame design was on the stability of the Go-kart and safety of the driver.The MS light weight steel has been employed for the frame to reduce the overall weight. To check the feasibility of the frame design, finite element analysis has been done. The results obtained showed that theframe design was safe under maximal impact load conditions. Motor, the heart of the electric vehicle wasselected and installed in such a way that it can perform well for an extended run time. BLDC motor was selected in this case. Speed control of the kart was done using a Motor controller. The kart is provided witha chain drive to achieve maximum efficiency in transmission of power from the motor to the wheels. Hydraulic disc brakes were provided for smooth and effective braking under both dry and wet conditions.Design calculations were carried out and optimum results were obtained