Peak Impact Force Research Articles

Testing the shock protection performance of Type I construction helmets using impactors of different masses.

Wearing protective helmets is an important prevention strategy to reduce work-related traumatic brain injuries. The existing standardized testing systems are used for quality control and do not provide a quantitative measure of the helmet performance. To analyze the failure characterizations of Type I industrial helmets and develop a generalized approach to quantify the shock absorption performance of Type I industrial helmets based on the existing standardized setups. A representative basic Type I construction helmet model was selected for the study. Top impact tests were performed on the helmets at different drop heights using two different impactor masses (3.6 and 5.0 kg). When the helmets were impacted with potential impact energies smaller than the critical potential impact energy values, there was a consistent relationship between the peak impact force and the potential impact energy. When the helmets were impacted under potential impact energies greater than the critical potential impact energy values, the peak impact forces increased steeply with increasing potential impact energy. A concept of safety margin for construction helmets based on potential impact energy was introduced to quantify the helmets' shock absorption performance. The proposed method will help helmet manufacturers improve their product quality.

Experimental investigation of brain contusion characteristics and dynamic response in low-age children using an animal model

IntroductionBrain contusion is a prevalent traumatic brain injury (TBI) in low-age children, bearing the potential for coma and fatality. Hence, it is imperative to undertake comprehensive research in this field. MethodsThis study employed 4-week-old piglets as surrogates for children and introduced self-designed devices for both free-fall drop impact tests and drop-hammer impact tests. The study explored the characteristics of brain contusion and dynamic responses of brain under these distinct testing conditions. ResultsBrain contusions induced by free-fall and drop-hammer conditions both were categorized as the coup injury, except that slight difference in the contusion location was observed, with contusion occurring mainly in the surrounding regions beneath the impact location under free-fall condition and the region just right beneath the impact location under drop-hammer condition. Analysis of impact force and intracranial pressure (ICP) curves indicated similar trends in impact forces under both conditions, yet different trends in ICPs. Further examination of the peak impact forces and ICPs elucidated that, with increasing impact energy, the former followed a combined power and first-order polynomial function, while the latter adhered to a power function. The brain contusion was induced at the height (energy) of 2 m (17.2 J), but not at the heights of 0.4, 0.7, 1, 1.35 and 1.7 m, when the vertex of the piglet head collided with a rigid plate. In the case of a cylindrical rigid hammer (cross-sectional area constituting 40 % of the parietal bone) striking the head, the brain contusion was observed under the energy of 21.9 J, but not under energies of 8.1 J, 12.7 J and 20.3 J. Notably, the incidence of brain contusion was more pronounced under the free-fall condition. ConclusionsThese findings not only facilitate a comprehensive understanding of brain contusion dynamics in pediatric TBIs, but also contribute to the validation of theories and finite element models for piglet heads, which are commonly employed as surrogates for children.

Experimental and numerical studies on AFRP-reinforced thin-walled tubes under axial impact loading

With the increase in global threats to infrastructure, from unforeseen events particularly in steel structures, there is a growing urgency to strengthen the impact resistance of steel elements. This research aimed to investigate the potential of using AFRP (Aramid Fiber Reinforced Polymer) to improve the energy absorption and crushing resistance of thin-walled circular hollow steel (CHS) tubes subjected to axial impact loads. Key aspects of the investigation include conducting a series of experiments to evaluate the impact of AFRP layer thickness, steel tube thickness, and impact velocity on structural performance. The performance metrics were characterized by analyzing impact force versus displacement, energy absorption capacity, peak crush load, and mean crush load. The results show that AFRP strengthening significantly enhances peak load capacity, energy dissipation, and impact force absorption compared to plain steel tubes. The AFRP-strengthened specimens exhibit higher specific energy absorption (SEA) and crushing force efficiency (CFE) compared to non-strengthened specimens, with peak force increasing by 18 % to 160 % for low external energy and 14 % to 190 % for high external energy. The three-dimensional finite element (FE) model accurately predicts load-carrying capacity and AFRP failure, validated against experimental tests. This study provides quantitative evidence of the effectiveness of AFRP reinforcement in improving the crash performance of thin-walled tubes under axial impact loading, highlighting the potential for optimizing AFRP strengthening techniques in structural applications.

Cell Design in Crash Box to Increase the Energy Absorption Efficiency

Researchers have completed many methods to increase the ability of thin tubes to absorb impact energy. Various methods are proposed covering the use of different materials, including new designs, which are expected to improve their performance. This study aims to obtain an Impact Energy Absorber (IEA), which has a low peak impact force and has better crash force efficiency (CFE), energy absorption (EA), and specific energy absorption (SEA). This study made a design change from an empty square tube to a square tube with a cell structure inside. A thin-walled box in the form of a box with a base size of 50 mm x 50 mm without a lid and a height of 150 mm with a thickness of 2 mm was used in this study. A load strikes the tube from the axial direction with a speed of 100 m/s while the other end is supported by fixed support. Deformation, impact force, and absorbed energy were recorded in all types of specimens. The results showed an increase in the reaction force between boxes that were given cells compared to empty ones. While the addition of cell variations from 1 to 2 did not experience a significant change in the impact force. The maximum deformation decreases with the number of cells, while the energy absorbed per unit length increases. The deformation pattern changes due to cells in the box because there is an obstacle when it is deformed towards the outside of the tube. The results of this study are considered in manufacturing high-speed crash boxes.

Lower Extremity Kinematic and Kinetic Characteristics as Effects on Running Economy of Recreational Runners.

This study aimed to determine associations between running economy (RE) and running sagittal plane kinematic and kinetic parameters. A total of 30 male recreational runners (age: 21.21 ± 1.22 yr, V̇O 2max : 54.61 ± 5.42 mL·kg -1 ·min -1 ) participated in two separate test sessions. In the first session, the participant's body composition and RE at 10 and 12 km·h -1 were measured. In the second session, measurements were taken for the sagittal plane of hip, knee, and ankle angles and range of motion (ROM), as well as ground reaction force. Moderate correlations were found between lower energy costs at 12 km·h -1 and smaller hip flexion at toe-off ( r = 0.373) as well as smaller peak hip flexion during stance ( r = 0.397). During the swing phase, lower energy costs at 10 km·h -1 were moderately correlated with smaller peak knee flexion and smaller knee flexion and extension ROM ( r = 0.366-0.443). Lower energy costs at 12 km·h -1 were moderately correlated with smaller peak hip and knee flexion as well as knee extension ROM ( r = 0.369-0.427). In terms of kinetics, there was a moderate correlation between higher energy costs at 10 km·h -1 and larger peak active force, as well as larger peak braking and propulsion force ( r = -0.470-0.488). Lower energy costs at 12 km·h -1 were moderately to largely correlated with smaller peak impact and braking force ( r = 0.486 and -0.500, respectively). Regarding the statistical parametric mapping analysis, most outcomes showed associations with RE at 10 km·h -1 , including knee flexion (42.5%-65.5% of the gait cycle), ankle plantarflexion (32.5%-36% of the gait cycle), active force (30.5%-35% of the stance phase), and propulsion force (68%-72.5% of the stance phase). Lower energy costs at 12 km·h -1 were correlated with smaller hip flexion (5.5%-12% and 66.5%-74%) and smaller knee flexion (57%-57.5%) during the running gait cycle. This study indicates that biomechanical factors are associated with RE in recreational runners. To design effective training methods to improve RE, coaches and runners should focus on the sagittal plane kinematics of the hip, knee, and ankle, as well as lower vertical and horizontal kinetic parameters.

Dynamic responses of concrete-filled steel tubes impacted horizontally by a rigid vehicle: Experimental study and numerical modelling

Concrete-filled steel tubes (CFSTs), composed of an outer tube made of steel as the confining material and an inner concrete core, have been popularly utilised as high-rise building columns and urban bridge piers owing to their superior structural behaviour. Since the invention of CFSTs, their mechanical performance under static and seismic loading conditions have been extensively studied, while the investigation on their dynamic behaviour under impact loading is relatively limited. Of these limited studies about CFSTs under impact loading conditions, most experiments were completed using a drop-hammer testing facility or a pendulum-hammer testing device. Against this background, this study investigated six large CFSTs being impacted horizontally by a rigid vehicle to analysis their dynamic response. All specimens were vertically placed with the bottom pedestal fixed on the lab floor and the top end free. The main parameters of these CFSTs included the impact velocity (i.e., vi = 3.16–7.18 m/s), the CFST section size (i.e., D = 180–300 mm), as well as the CFST column height (i.e., hc = 1500–2100 mm). Test results revealed that, (1) all CFSTs experienced a bending-dominant failure when impacted horizontally by a rigid vehicle; (2) the impact velocity had a positive correlative trend with the peak impact force Fpeak and the peak lateral displacement δpeak of the CFST column; (3) a larger section size of the CFST column resulted in a higher flexural stiffness and a larger flexural capacity, thus leading to a higher Fpeak, a smaller time duration T and a smaller δpeak; (4) the column height would affect the inertial response of the CFST column; a larger column height led to a larger Fpeak caused by the larger inertia effect of the CFST segment above the impact point. Finite-element model was established on the platform of LS-DYNA to simulate these CFSTs under horizontal impact loading, which was able to predict both impact force–time history curves and lateral displacement–time history curves with reasonably accuracy.

Mechanical performance, impact behavior and environmental assessment of coal furnace slag based low-carbon ultra-high performance engineered cementitious composites (UHP-ECC)

This study aimed to optimize the utilization of industrial solid waste through developing a high-performance cement-based composite material (UHP-ECC), incorporating coal furnace slag (CFS) and waste rubber powder (RP). The investigation concentrated on the effects of introducing 10% RP into UHP-ECC and replacing ordinary Portland cement (OPC) with CFS at varying proportions (0%, 20%, 40%, 60%) on mechanical properties, impact resistance, and sustainability. The mixtures underwent a comprehensive characterization, including mechanical tests, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), to clarify hydration mechanisms and microstructural features. The results revealed that the addition of 10% rubber led to flaws, resulting in a minor reduction in compressive strength from 143.2 MPa to 132.2 MPa. Substituting 20% with CFS resulted in a denser matrix, raising the compressive strength to 135.5 MPa. CFS decreased the initial cracking strength and matrix fracture toughness, with tensile strain peaking at 8.05% and narrower crack widths. More CFS content yielded a slight decrease in peak impact force but induced more fine cracks and enhancing ductility. Moreover, as CFS is a waste product generated at high temperatures, the mixture demonstrated outstanding impact performance at 150 °C, absorbing rather than converting more energy into kinetic energy. Comparative analysis against similar mixtures highlighted UHP-ECC's strengths in embodied carbon, embodied energy, and material cost. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) assessment identified the CFS40-R10 as better mixture, achieving a balance between mechanical performance, cost-effectiveness, and sustainability. Microscopic analysis revealed that up to 40% CFS facilitated hydration, and the 60% CFS mixture exhibited the lowest total mass loss at high temperatures.

Protection performance of a novel anti-collision guardrail with recycled foamed concrete under vehicle collision

Highway guardrails play an important protective role in transportation. However, most traditional highway guardrails are poor at buffering and energy absorption, which cannot guarantee the safety of passengers in traffic accidents. To address this problem, recycled foamed concrete (RFC) was combined with thin-walled steel shells to prepare a novel recycled foamed concrete anti-collision guardrail (RFCG) in current study. The energy absorption and protection performance of the guardrail were evaluated by full-scale model impact tests and numerical simulations. The results revealed that compared with standard guardrail (SG), RFCG performed better in buffering and energy absorption, yielded less damage to vehicles, exhibited a peak impact force reduction rate of 54.46%, and reduced the manufacturing cost by 5.5% per kilometer. A finite element model for the guardrail was proposed. The numerical simulation results matched well with the experimental results and the accuracy of finite element model was validated.

Dynamic responses of steady-state transition structures under impact loading

Advancements in materials science and mechanical system have spurred widespread investigation into non-traditional structures. In particular, engineers have shown interest in steady-state transition structures with phase transition properties. In this paper, a three-dimensional steady-state transition structure was established using the genetic algorithm and three-dimensional expansion, on which the low-velocity impact tests were carried out. Force response and energy absorption of the steady-state transition structures under impact were studied. From the force response and energy absorption curves, it can be seen that the steady-state transition structures absorb and store portion of impact energy temporarily, gradually releasing it after impact peak. This unique energy behavior results in a steady state transition structure with a long impact response time and a low peak impact force under impact. In addition, investigation into energy transfer within these structures reveals that energy oscillations occur among multilayered bistable surfaces during steady-state transitions, further improving the energy dissipation. Further, the dynamic response and damage modes of the honeycomb structure and the steady state transition structure were compared, showing that the damage mode of the steady state transition structure under the impact is an overall damage, in contrast to the penetration damage of the honeycomb structure. Notably, the steady-state transition structures showcase a higher proportion of elastic strain energy during impacts, effectively delaying structural damage onset, and dispersing impact energy, thus enhancing impact resistance. In light of these findings, the demonstrated behavior of steady-state transition structures in absorbing and dissipating impact energy showcases their potential as promising avenues for the development of more effective impact protection strategies.

Evolution of the impact force of supercooled water droplets with different shapes on a superhydrophobic cold surface

We conducted a numerical study on the evolution of the impact force of supercooled water droplets with different shapes when they do not fully rebound on a superhydrophobic cold surface. The evolution of peak impact forces and their characteristic times with Weber number (We) were focused. The presence of a cold surface had a relatively less influence on the evolution of the first peak impact force but had a significant influence on the second peak impact force when We > 60. The sudden increase in the second peak impact force was closely related to the formation and subsequent collapse of cylindrical-like structures inside impinging water droplets. To incorporate the quantitative influence of droplet shapes, we introduced correction factors based on the aspect ratio (AR) in the fitting expressions for peak impact forces and their characteristic times. Specifically, we utilized AR (AR ≤ 1.0) and AR1/6 (AR >1.0) when 3 < We < 40, or AR4/3 (AR ≤ 1.0) and AR1/2 (AR > 1.0) when 40 < We < 100 as correction factors for the first peak impact force. Moreover, we employed AR−2 as the correction factor for the first peak characteristic time and AR−1/3 for the second peak characteristic time. These corrections extended the applicability of the fitting expressions to supercooled water droplets with different shapes.

Comprehensive Numerical Modeling of Prestressed Girder Bridges under Low-Velocity Impact

Accidental collisions involving over-height trucks that exceed vertical clearance limits and bridge superstructures frequently happen, resulting in compromised girders and potential threats to structural safety and performance. The numerical simulation of large-scale prestressed girder bridge collisions poses challenges due to the associated nonlinearities, as well as the limited availability of large-scale experimental testing data in the literature due to cost and complexity constraints. This study introduces a numerical modeling approach to efficiently capture the response of prestressed girder bridges under lateral impact loads. A finite element (FE) model was developed using LS-DYNA and meticulously validated against experimental data from the literature. The study explored four methods for applying prestressing forces and evaluated the performance of four concrete material constitutive models, including the Continuous Surface Cap Model (CSCM), Concrete Damage Plastic Model (CDPM), Karagozian & Case Concrete (KCC) model, and Winfrith concrete model, under impact loads. Furthermore, an impact study was conducted to investigate the influence of impact speed, impact mass, and prestressing force on the behavior of prestressed girder bridges. Utilizing the dynamic relaxation (DR) approach, the developed FE model precisely captured the response of prestressed girders under impact loads. The CSCM yielded the most accurate predictions of impact forces, with an error of less than 8%, and demonstrated a strong ability to predict damage patterns. Impact speed, mass, and the presence of prestressing force showed a significant influence on the resulting peak impact force experienced by the girder. Furthermore, the study underscores the composite nature of the bridge’s response and emphasizes the importance of analyzing the bridge as a whole rather than focusing solely on individual girders.

Impact force of non-Boussinesq gravity-current head against a circular cylinder above the seabed

We study the impact force of the gravity-current head on a circular cylinder above the seabed for the non-Boussinesq effect using a large-eddy simulation model well validated against laboratory data. Most existing studies of the gravity current were for the slight density difference between the current and the ambient fluid, assuming the density is constant using the Boussinesq approximation. The aim of the present study, however, is about gravity current of significant density difference. We detail the coherent turbulence structure of the gravity current and the transient oscillation of the impact force on the cylinder over a range of density differences varying from (ρs−ρa)/ρa=0.02 to 2 for the elevation relative to the diameter of the cylinder E/D=0.05, 0.4 and 1.0. The velocity and vorticity field in the current show a gravity-current head separating from the primary current driven by excess pressure at the back, with a structural similarity almost independent of the density difference. The gravity-current head’s frontal and wake velocities are determined from the numerical simulations and related to the buoyancy speed. The impact force on the cylinder rises to a peak immediately after the arrival of the gravity-current head. We propose a set of new drag and lift coefficients using a gravity-driven pressure as a reference for the impact force of the non-Boussinesq current. The peak impact force, made dimensionless by the gravity-driven pressure, is found to be relatively independent of the density difference, regardless of how large the current density may be.

Cumulative-impact method for the assessment of dynamic crush curve of crashworthy devices

Crashworthy devices are integral for protecting bridges from vessel collisions, typically evaluated through finite-element methods. However, experimental verification is challenging owing to the impracticality of using large-scale, high-velocity vessels. In this study, a cumulative-impact method is proposed, which is theoretically and experimentally validated. It uses a small-scale impactor in multiple impacts to determine crashworthy device dynamic crush curve based on energy balance theory. The accuracy of the proposed method depends on the number of impacts and the impact velocity. The relative errors are < 5% for the peak impact force and residual deformation, if the number of impacts is < 5 and the impact velocity is > 3 m/s. A parametric study explores application conditions for the cumulative-impact method through horizontal-impact tests, indicating that small-scale multi-impacts and large-scale single impacts have consistent dynamic crush curves. The proposed method is sufficiently accurate to be used to determine the safety assessment of bridges under vessel collisions.

Skill shapes functional movement variability and exploration tendencies: the effect of skill under changing environmental constraints on the emergence of creative action in a divergent kickboxing task

ABSTRACT Creative actions are both functional and unique, furnishing significant performance advantages in sport. We examined the proposition that the occurrence of creative actions has a common behavioural mechanism, exploration, that is driven by motor skill. Using a kickboxing task, we assessed the effect of skill on the degree of uniqueness and functionality of striking actions, which were determined using full body kinematic data and measures of peak impact force respectively. We expected that, since the task was designed to stimulate exploration (by varying the body-scaled distance to a target boxing bag), expert kickboxers (N = 21) would be more creative due to the functional characteristics of their actions in comparison to novices (N = 21). The results generally supported expectations, indicating that experts demonstrated a significantly greater number of functional action variants than novices. And, when functionality was not accounted for, both experts and novices were equally capable of developing unique actions. Interestingly, for both groups, the number of unique actions exhibited was strongly positively correlated with the tendency to distribute exploration of actions broadly across action variants. However, experts revealed a significantly reduced tendency to distributed exploration across action variants compared to novices which was likely due to the experts avoiding less functional actions at close and far distances to the target. Promoting creative action occurrence during practice is linked to exploration and functional movement variability which may be stimulated by learning environments and tasks that are scaled to individual constraints.

Study on dynamic response of cushion layer-reinforced concrete slab under rockfall impact based on smoothed particle hydrodynamics and finite-element method coupling

Abstract In the rockfall prevention and control project, the reinforced concrete (RC) slab and sand (gravel soil) soil cushion layer are commonly used to form the protection structure, thereby resisting the rockfall impact. Considering that the oversized deformation of the cushion layer under impact load using the finite element simulation cannot converge, this article establishes a numerical calculation model using smoothed particle hydrodynamics–finite-element method coupling (SPH–FEM). First, the standard Lagrange finite-element mesh is established for the whole model using ABAQUS, and then the finite-element mesh of the soil cushion layer is converted to SPH particle at the initial moment of the calculation, and finally the calculation results are solved and outputted. The results indicate that, compared with the results of the outdoor rockfall impact test, the relative errors of the rockfall impact force and the displacement of the RC slab are within 10%, which proves the rationality of the coupling algorithm; moreover, in terms of the numerical simulation, the SPH–FEM coupling algorithm is more practical than the finite element for reproducing the mobility of the rockfall impacting the sand and soil particles. In addition, at an impact speed of less than 12 m·s−1, the cushion layer is able to absorb more than 85% of the impact energy, which effectively ensures that the RC slab is in an elastic working state under small impact energy and does not undergo destructive damage under large impact energy; the peak impact force of the rockfall is approximately linear with the velocity, and the simulated value of the peak impact force is basically the same as that of the theoretical value of Hertz theory; the numerical simulation is good for reproducing the damage process of the RC slab in accordance with the actual situation. The SPH–FEM coupling algorithm is more justified than the FEM in simulating the large deformation problem, and it can provide a new calculation method for the design and calculation of the rockfall protection structure.

Impact loading of glued laminated timber beams without finger-joints

Progressive collapse can be triggered by impact loading from vehicles or other objects and propagated by impact loading from falling debris. Therefore, the correct modeling of impact loading is necessary to assess the resistance of a structure against progressive collapse. As the number of timber buildings increases, the importance of adequate considerations of impact loading is growing. Previous research on impact loading of wood or timber was carried out on small clearwood specimens or on single boards. However, modern timber buildings use advanced wood-based composites, such as glued laminated timber and laminated veneer lumber. The characteristics of these materials are widely different from clearwood and single boards. In this paper, energy-based equations are derived for the peak impact force and the dynamic strength increase factor. These are quantified by pendulum impact hammer tests on 95 full-size glued laminated timber beams. The results are applied in a calculation example to demonstrate their potential use in practice.

Impact response of lightweight steel foam concrete composite slabs: Experimental, numerical and analytical studies.

This paper presents a study on the low-velocity impact response of lightweight steel foam concrete (LSFC) composite slabs. The LSFC composite slab consisted of a W-shaped steel plate, foam concrete and oriented strand board (OSB). Low-velocity impact tests on the LSFC composite slabs were conducted by employing an ultra-high heavy-duty drop hammer testing machine. The tests revealed the failure mode, impact force and displacement response of LSFC composite slabs. The effects of density and thickness of foam concrete and drop height on the peak impact force and energy absorption ratio were investigated. A finite element (FE) model was set up to predict the impact resistance of the LSFC composite slabs, and a good agreement between simulation and test results was achieved. In addition, an equivalent-single-degree-of-freedom (ESDOF) model was set up to predict the displacement response of the LSFC composite slabs under impact loading.

Study on the low‐velocity impact response of the repaired carbon fiber‐reinforced plastic laminates: Bonded versus scarf repair

AbstractExperimental and simulation studies of the response of bonded‐repaired and scarf‐repaired carbon fiber‐reinforced polymer laminates under the low‐velocity impact (LVI) were carried out. The center‐ and eccentric‐repaired laminates were prepared for experiments. The experimental results verify the validity of the finite element model in terms of the force response and different modes of damage. The effect of impact energy and the variation of repair position on the impact response of the laminate was investigated based on the benchmark model. The bonded repaired laminates have higher peak impact forces and lower energy absorption than the scarf‐repaired laminates; the damage of the bonded repaired laminate is mainly intralaminar damage and delamination damage of the patch; the adhesive of the scarf repair is prone to failure, leading to poor impact resistance. The relative positions of the impact point and the patch determine the impact response of a laminate repaired at different locations. The impact point at the edge of the patch has a detrimental effect on the repaired laminate. The impact point vertical position near the bottom hole edge of the parent plate in the scarf‐repaired case harms the impact resistance of the laminate.Highlights The low‐velocity impact response of bonded versus scarf‐repaired laminates was compared. Bonding repairs provide superior impact resistance to damaged laminates than scarf repairs. The risk of adhesive failure in scarf repair is significantly higher than in bonded repair. The relative position of the damage (repair) to the impact point critically influences the impact response. Impacts near the edge of the initial damage hole can cause severe damage to scarf‐repaired laminates.

Scaling laws of low-velocity impact response for RC beams: Impact force and reaction force

Predicting the low-velocity impact response of the prototype based on the scaled test results is one of the significant topics in structural design and protection. Thus, reliable similarity laws are required to bridge the dynamic similarity between models and prototypes. In this study, numerical modeling was carried out by considering plastic damage and strain rate effects. Then, the impact responses of four series reinforced concrete beams satisfying traditional similarity laws were analyzed. The largest beam section size reached 600 mm × 1000 mm. The scaling effects on the impact force profiles (comprising three Types) and reaction force profiles of the beam were investigated. Several characteristic points were defined for the available simplified profiles of impact and reaction forces. It is shown that the scaling effects on each characteristic are not consistent. As the theoretical scale factor increases, the characteristics such as the peak impact force, the positive peak of the reaction force, and its plateau satisfy the traditional similarity law, whereas the characteristics such as the impact force duration and the negative peak of the reaction force do not. Therefore, modified dynamic scale factors for the characteristics of impact and reaction force profiles from models to prototypes were proposed. Based on the suggested scaling laws, the simplified profiles of impact and support reaction forces of the prototype can be predicted. It is expected that it will help researchers to conduct experimental studies and optimized designs on structural impact resistance.

Experimental and numerical investigation on high-velocity hail impact response of TC4 titanium alloy plates

This work studied the dynamic response of hail impacting on TC4 titanium alloy plates under different influence factors. Experiments were performed according to China Civil Aviation Regulations Airworthiness Standards. The damage to the plate was recorded by in-situ cameras. The experimental results indicate that the greater the hail velocity, the more severe the damage to the titanium alloy plate. In the simulation, Smoothed Particle Hydrodynamics (SPH) method was used to model the hail. The reliability of numerical model was verified by the comparison with the test results of hail impact response. The numerical results show that the deformation of the plate increases as the impact angle and hail diameter increases. Moreover, the changes in impact angle and position will both alter the displacement and strain distribution within the plate. Through comparative analysis of the impact velocity, hail diameter, impact angle, and impact position on the impact force peak, plastic strain energy, and maximum kinetic energy of the plate, it is found that changes of hail diameter and velocity have great effect on the response of titanium alloy plate, and the impact position has little effect on it. There is a power-law relationship between the hail impact peak force and the hail velocity with an index of 1.912.