Dynamic Impact Loading Research Articles

Low/intermediate speed impact‐induced ignition and damage of a novel high‐energy solid propellant

AbstractThe damage and ignition response of a novel propellant is investigated using a modified split Hopkinson pressure bar (SHPB). The mechanical response of the propellant exhibits strong strain rate dependency following a power law. The whole process from mechanical damage to onset of ignition, deflagration and potential deflagration to detonation transition (DDT) under different strain rates (1000–5000 s−1) is captured via high‐speed photography and digital image correlation (DIC). To clarify the onset and extent of the resulting reaction in terms of the mechanical damage caused by impact, meso‐scale analysis is used to evaluate the propellant before and after dynamic impact loading. The ignition response under impact loading is mainly caused by shear flow, and ignition after multiple impacts due to the reflection of stress waves. Dense debris clouds produced by the first impact are observed in the case of a strain rate of 5000 s−1 leading to DDT when the second impact initiated ignition.

Dynamic tensile mechanical properties of thermally damaged sandstone under impact loads and the influence mechanism of composition

The stability of surrounding rock in the combustion void is the key to continuous, safe, and efficient gas production in an underground coal gasification project. The key factors influencing the stability of surrounding rock in the combustion void are high temperature and impact dynamic load. At the same time, rock structure failure mainly depends on the rock materials’ tensile strength. Therefore, it is fundamental to study the dynamic tensile mechanical properties of thermally damaged rocks to control the surrounding rock stability of the combustion void in UCG projects. This paper used the coal measures as the research object. The dynamic direct tensile test of thermally damaged sandstone was carried out using a high-temperature load system and split Hopkinson tension bar (SHTB) test system. The test results showed that the dynamic tensile strength of sandstone increased linearly with the increase in strain rate. In contrast, it increased first and then decreased with temperature. In addition, the nonlinear regression method was applied to establish the prediction model of dynamic tensile properties of thermally damaged sandstone. XRD analyzed the composition and mass fractions of sandstone. From the standpoint of composition change, the change mechanism of the mechanical properties of thermally damaged coal measured in sandstone was illustrated.

Mechanical behaviors of cementations matrix composites reinforced with basalt weft-knitted spacer fabric under low-velocity impact

The attention of this paper is focused on the impact resistance behavior and reinforcing mechanism of cement-based composites reinforced with weft-knitted spacer fabrics (FKRCs). Composites were manufactured with basalt spacer fabrics and calcium sulfoaluminate cement, both of which are eco-friendly materials. Three kinds of FKRCs with varying needle span distances of the spacer fabrics were compared with plain concrete and concrete reinforced with basalt fibers via a static-bursting test and low-velocity impact test. In addition, the failure morphologies of damaged specimens were analyzed. The experimental results revealed that the basalt spacer fabric was able to obviously enhance the impact resistance and energy absorption capacity of the concrete, while the reinforcing effect of basalt fibers was relatively restricted. In addition, spacer fabrics played a crucial role in retarding the crack generation and propagation in the cement matrix by the textile bridging effect. Furthermore, FKRCs were more sensitive to dynamic impact load, exhibiting a higher maximum peak load but lower maximum displacement. With the increase of span distances, the impact resistance of the specimens was enhanced with higher maximum impact load and energy absorption, and the brittleness of plain concrete was improved. In addition, the spacer yarn structure exhibited considerable effects on the impact behavior of the composites rather than basalt spacer fabrics. Therefore, the FKRC is suitable for structural components that require higher impact resistance in engineering applications.

Impact of dynamic loading on pavement deflection measurements from traffic speed deflectometer

Traffic speed deflectometer (TSD) provides an efficient way for evaluating pavement condition. The current principle is to convert measured deflection slopes into the deflection basin using the Area Under The Curve (AUTC) method based on the time-space transform and elastic material theory. This study aims to investigate impact of dynamic loading due to pavement roughness on TSD measurements. Semi-analytical finite element (SAFEM) method was developed to simulate dynamic moving loads on flexible pavements with viscoelastic asphalt layer. The variations of pavement deflection and deflection velocity were found increasing linearly with dynamic loading coefficient (DLC), especially for deflection velocity. The average relative error between the actual deflection basin and the one from the AUTC method could be 15% at DLC of 0.1 with the highest error for the maximum deflection. This indicates the necessity of developing correction method of TSD deflection measurements on rough pavements.

Experimental and computational study on local buckling of standard and improved cold-formed square hollow sections under static and dynamic loading

Because of aesthetics, economic advantages, easy composite member production and design, and a wide range of standard sizes, hollow sections are commonly utilized in various construction industry applications worldwide, including conventional and unique free-form structures. However, the sections must fulfill more restricted circumstances to avoid early local buckling. The behavior of cold-formed square hollow sections with different wall thicknesses under static and dynamic transverse impact loading was investigated experimentally and numerically in this study. A method that uses rivet nuts is proposed to improve the dominant local buckling behavior, which is observed in the experimental studies and causes a relatively low bending strength, for providing convenience in field applications. The effectiveness of the proposed method is demonstrated experimentally and numerically using finite-element analysis. In addition to conventional measurement techniques, motion analysis is performed using digital image correlation to measure the displacements during static and dynamic tests. With the proposed technique, the local buckling strength of the square hollow sections is increased by 64% under static loading and by approximately 40–85% under dynamic loading compared with standard square hollow sections, respectively. This is due to the internal stiffness plate, steel threaded rods, and rivet nut configuration connecting the flanges and webs of the square hollow section, which ensures load sharing between the section parts. Additionally, steel threaded rods prevent early buckling of the internal stiffness plate. In addition, parametric analysis results show that the thickness of the internal stiffness plate has a negligible effect on the local buckling strength, although the presence of an internal stiffness plate increased the strength. The numerical analysis results indicate that the local buckling behavior of both conventional and improved square hollow specimens can be predicted with acceptable errors in terms of their strength and damage modes using finite-element analysis models.

Study on Damage Characteristics and Failure Modes of Gypsum Rock under Dynamic Impact Load.

The objective of this work was to investigate the damage characteristics and failure modes of gypsum rock under dynamic impact loading. Split Hopkinson pressure bar (SHPB) tests were performed under different strain rates. The strain rate effects on the dynamic peak strength, dynamic elastic modulus, energy density, and crushing size of gypsum rock were analyzed. A numerical model of the SHPB was established using the finite element software, ANSYS 19.0, and its reliability was verified by comparing it to laboratory test results. The results showed that the dynamic peak strength and energy consumption density of gypsum rock increased exponentially with strain rate, and the crushing size decreased exponentially with the strain rate, both findings exhibited an obvious correlation. The dynamic elastic modulus was larger than the static elastic modulus, but did not show a significant correlation. Gypsum rock fracture can be divided into crack compaction, crack initiation, crack propagation, and breaking stages, and is dominated by splitting failure. With increasing strain rate, the interaction between cracks is noticeable, and the failure mode changes from splitting to crushing failure. These results provide theoretical support for improvements of the refinement process in gypsum mines.

Numerical and Experimental Behavior Analysis of Slabs Strengthened Using Steel Plates and Slurry-Infiltrated Mat Concrete (SIMCON) Laminates

This study has two main aims; firstly, investigating the behavior of slabs that are strengthened with different types of reinforcements and with Slurry-Infiltrated Mat Concrete (SIMCON) laminates, having different dimensions and thicknesses and subjected to static and dynamic (impact) loads. Secondly, the development of a non-linear finite element (FE) model to simulate the behavior of the tested slabs utilizing the ABAQUS/Standard package. The modeling of the NSC slabs strengthened with either SIMCON or steel plates involves using three-dimensional solid elements that are partially integrated with the modeling of concretes using the 8-node brick element (C3D8R). The results of the experimental and numerical investigations are compared to examine whether the slab modeling is sufficient. The comparison includes the element type, material characteristics, real constants, and convergence study. The predicted ultimate load-carrying capacity versus vertical deformation response is compared with the lab results that correspond with it, as obtained via the FE analysis of all tested slabs. In addition, the results of the FE analysis of slab specimens that are strengthened with steel plates were compared to the results of the ones strengthened using SIMCON laminates. The obtained results have led to a number of significant observations. Considering the punching shear strength, it was found that using SIMCON strengthening in different dimensions increased the slab’s punching shear capacity and outperformed steel-strengthened slabs. As for the plate stiffness, SIMCON-strengthened slabs presented higher stiffness rates than steel-strengthened slabs, to the extent that even 20 mm SIMCON strengthening outperformed the steel plate-strengthened slabs of any thickness or dimensions. The axial load-displacement relationships indicate that all the numerical models show a stiffer behavior when compared with the experimental axial load-displacement relationships. The slab thickness of SIMCON significantly affects the load-carrying capacity, and it increases with the increase in thickness. Likewise, using strengthening from steel plates gives a higher load-carrying capacity. Finally, since the results of the yield line analyses for these slabs are found to match the experimental results closely, this method is considered to be suitable for practical use in determining the strength of plated slabs. Therefore, the conclusion is drawn that the proposed FE model can be sufficiently used in evaluating the dynamic responses of slabs strengthened with SIMCON or steel plates and subjected to cyclic and impact load.

Effects of process parameters and loading direction on the impact strength of additively manufactured 18%Ni-M350 maraging steel under dynamic impact loading

The microstructural and damage evolution of 18%Ni M350 maraging steel fabricated by laser-based directed energy deposition (DED) process under dynamic impact loading are investigated in this study. The influence of additive manufacturing (AM) processing parameters, including laser power, powder feed rate, and energy area density (EAD) are discussed. The mechanical testing of the additively manufactured alloy was done using the split Hopkinson pressure bar (SHPB) system. The dynamic impact test was conducted using strain rates ranging from 100 to 4000 s−1. The test was conducted on cylindrical specimens (7 mm diameter and 8 mm long) with axes parallel to the build direction (Z-axis) and perpendicular (X- and Y-axis) to the build direction to evaluate the effects of loading directions on mechanical responses and microstructural evolution in the alloy under the impact loading conditions. The test results revealed that the materials processed using the lowest EAD parameters exhibit the greatest impact strength under dynamic impact loading for all directions. Specimens impacted along the build direction (Z-axis) exhibit a continuous drop in peak flow stress once the strain rates exceeded 2300 s−1 indicating the greatest susceptibility to thermal softening at high strain rates. Strain localization leading to the formation of adiabatic shear bands (ASB) was observed in some specimens. Cracks developed along the ASBs, while some AM-process-related defects, such as the lack-of-fusion, interacted with adiabatic shear bands, promoting cracking inside the shear bands. Despite possessing the highest impact strength, the materials produced by the lowest EAD parameters are the most susceptible to the development of adiabatic shear bands leading to cracking and fracture.

Axial impact behaviors of UHPC: The roles of nanomaterials and steel fibres

With the gradual maturity of nanotechnology, many nanomaterials have been used to modify ultra-high performance concrete (UHPC) to improve its performance. In the course of use, concrete structures will suffer from various forms of dynamic impact loads, resulting in serious damage. At present, the research on the dynamic properties of nanomaterials modified UHPC is still lacking. This study presents an experimental study on the axial impact behaviors of nanomaterials modified UHPC by Split Hopkinson Pressure Bar (SHPB). The effects of nanomaterials and steel fibres on failure patterns, dynamic compressive strengths, impact toughness, dynamic compression constitutive relationship and dynamic increase factor (DIF) of UHPC under different strain rates were analyzed and discussed. The results show that UHPC is strain rate sensitive. Steel fibre improves the dynamic compressive strength and impact toughness of UHPC, and reduces the strain rate sensitivity of UHPC. The effect of hook-end steel fibre on the impact performance of UHPC is generally better than that of straight steel fibre. Proper addition of nanomaterials can improve the axial compression impact properties of UHPC, but excessive nanomaterials will adversely affect the impact performance of UHPC. Under strain rate of 160 s−1, the dynamic compressive strength and impact toughness of UHPC were improved by 10.05 % and 5.70 % respectively by adding 2 % nano-CaCO3. Based on the experimental results, a recalibrated DIF model considering the coupling effect of nanomaterials and steel fibres is proposed for the UHPC, and it predicted the test results of the modified UHPC reasonably well.

Reinforcing effects of carbon nanotubes on cement-based grouting materials under dynamic impact loading

Carbon nanotubes (CNTs) are reasonable materials to modify the property of cement-based grouting materials to improve their strength and durability, optimize their pore structure, and reduce their carbon emissions. However, dynamic impact loading frequently occurs in underground engineering, while there is very limited research concerning the reinforcing effects of CNTs on cement-based materials under dynamic impact loading. Hence, in this work, we applied the split Hopkinson pressure bar to investigate the dynamic mechanical behaviors of CNTs cement-based grouting materials. The results exhibited that CNTs cement-based grouting materials presented superior impact resistance, with a maximum peak stress of 59.33 MPa. Compared with plain cement grouting materials, mixing CNTs and fly ash into cementitious composites could reinforce the dynamic compressive properties by 10.25%–31.86%. The impact resistance of CNTs cement-based grouting materials was more significant under high dynamic loading, enhancing the dynamic properties by up to 31.86%, which indicates that CNTs reinforcement is more efficient in impacting engineering. The strain nephogram and fractal dimension further suggested that the excellent capacity of the CNTs in cement-based grouting materials could be achieved after ultrasonic treatment. A mathematical physical model was then established for CNTs reinforcing cement-based materials, revealing the whole process of CNTs extraction from the cement-based and giving a factor that can measure reinforcement performance. The findings of this study not only promote that the CNTs cement-based grouting materials can enhance the dynamic loading properties and reduce cement usage, but also provide a theoretical basis for the subsequent research on the mechanism of the microscopic reinforcement of CNTs.

Analysis of the Influence of Silty Sands Moisture Content and Impact Velocity in SHPB Testing on Their Compactability and Change in Granulometric Composition

This paper presents the results of a test cycle of two types of silty sand (siSa) with different contents of fine fractions. Fine fractions are understood as soil grains with a grain diameter of less than 63 µm (as the sum of silt and clay fractions). The soils tested had a content of fine fractions of fSi+Cl,1 = 15.14% and fSi+Cl,2 = 20.48%, respectively, before the study. Changes in the content of these fractions after the experiments were analyzed. These experiments consisted of dynamic bar projectile impact loading, and a split Hopkinson pressure bar (SHPB) test stand was used in the study. Changes in the granulometric composition of the silty sands studied were carried out in a laser particle size analyzer, allowing measurement of fractional content in the grain size range from 0.01 µm to 3500 µm. As a result, a summary of changes in soil grain size curves in the range of fine fractions was compiled. Repeated trends were observed in the changes in the granulometric composition of the soil samples as a function of the moisture content of the soil sample (w1 = 0%, w2 = 5%, w3 = 10%, and w4 = 15%) and the impact velocity of the loading bar projectile for SHPB pneumatic launcher pressures (p1 = 1.2 bar → v1 = 12.76 m/s, p2 = 1.8 bar → v2 = 17.69 m/s and p3 = 2.4 bar → v3 = 21.32 m/s). The influence of the initial moisture content of the investigated soil on the value of the optimum moisture content obtained during its dynamic compaction was discussed. The trend in the behavior of the change in the granulometric composition of the tested samples was determined, taking the value of the initial moisture content of the soil in relation to the optimum moisture content of the reference sample as a reference. The largest percentage change in granulometric composition through an increase in the value of the silt and clay fraction relative to the reference sample fSi+Cl for both types of silty sand tested occurs for the same moisture content variant w2 = 5%–for soil fSi+Cl,1 = 15.14% there is an increase in the fine fraction of 11.08% and for soil fSi+Cl,2 = 20.48% there is an increase in the fine fraction of 15.17%. In general, it can be seen that more silty soil is more strongly susceptible to the phenomenon of grain crushing for moisture content w1 = 0% and w2 = 5% less than its optimum moisture content wopt,1 = 8.70%. In contrast, less silty soil is more susceptible to the phenomenon of grain crushing for moisture contents w3 = 10% and w4 = 15% greater than its optimum moisture content wopt,2 = 9.20%. The presented dynamic physical phenomenon of soil behavior is crucial during explosive and impact impacts on structures made of soil, e.g., as ground protection layers.

Dynamic response and impact loads in twin-barge floatover installation

Complex impact loads during the floatover installation will threaten the mating operations. This paper presents the experimental investigation on the impact loads and dynamic response in the twin-barge floatover installation. In the model test, two critical loads transfer scenarios were modeled, including 0% and 100% stages in which the topsides are initially connected and separated from the barges. The near-zero gaps between the topsides and the twin-barge are simulated at two stages with the aim of investigating the collision characteristics. The impact loads on mating units, mooring forces, hawser forces, as well as motions of the twin-barge and the topsides were investigated. It is found that the windward barge motions are much larger than the leeward barge in sway, roll and yaw directions. The larger barge sway and yaw motions occurred at the 100% stage compared with the 0% stage. Statistical results indicate that the 100% stage seems to induce the larger impact loads on mating units than the 0% stage. The lateral impact loads were comparable with the vertical loads, in which the maximum lateral impact loads were even greater than the vertical impact loads. The mooring and hawser lines at the 100% stage are subjected to larger loads.

Experimental investigation on the spalling failure of a railway turnout made from Hadfield steel

In a rail track structure, a turnout is used as a transition between straight and branching rails and therefore withstands complex dynamic rolling and impact loading. This paper reports a comprehensive failure investigation of a railway off-track turnout made from Hadfield austenitic cast steel. The worn turnout was examined using optical microscopy, scanning electron microscopy, micro-hardness, and quantitative X-ray diffraction analyses. A ball-on-disc sliding wear test was also applied to evaluate the impact of work-hardening on the wear property. The turnout exhibited surface embrittlement, severe cracking, delamination, and spalling characteristics. Severe plastic deformation of the worn turnout was observed with the formation of densely packed mechanical twins, which facilitated crack propagation. The rail top developed a gradient hardness (HV0.1) profile from the rail top of 8.9 GPa, the cracked subsurface of 5.9 GPa to the bulk steel of 2 GPa. The rail top was also found to have accumulated an extremely high residual compressive stress of 500–650 MPa. Strain induced martensite transformation was repeatedly evidenced by X-ray diffraction peak of the ferritic (110) plane although the highly strained and nanocrystallised ferrite was only detected on the severely deformed rail top. Comparative sliding wear tests showed highly deteriorated wear resistance of the strain-hardened rail top as compared to the bulk steel.

Finite element-based phase field simulation of complex branching crack propagation under different loads

The tensile failure of complex branching cracks will cause irreversible damage to the structures. In this paper, the effects of the crack orientations, the local branch lengths, and the different load forms on the crack propagation pattern and the bearing capacity of structures are investigated based on the phase field method and experimental research method. The results show that the bearing capacity and propagation patterns of the specimens change significantly with the change of the orientation of the Y-shaped crack under tensile load. The local branch length of the crack only affects the sequence in which the regional crack reaches the final failure and the bearing capacity of the specimen. Under the dynamic impact load, the bifurcation phenomenon occurs, and with the increase of the dynamic impact load, the number of bifurcations increases. The crack propagation pattern in the numerical simulation is completely consistent with the experiment, and the difference in the maximum reaction force is 2.5%.

Safety of Steel Arch Support Operation During Rock Bursts Under Explosive Atmosphere Conditions

Abstract Methane and coal dust explosions are among the most common causes of disasters in hard coal mining. Therefore, it is important for occupational safety in hard coal mines operating under methane and coal dust explosion hazards to identify possible ignition sources, whether due to natural or technical factors. One technical source of ignition can be mechanical sparks generated during operation of mechanical equipment and high surface temperatures of equipment components during operation. This paper presents the methodology and results of thermal imaging and strength testing of roadway support elements under dynamic loading. The goal of the tests was to identify the potential explosive atmosphere ignition sources during the operation of the support under the conditions of rock bursts. The scope of testing encompassed the temperature measurements by means of thermal camera of friction prop and yielding support frame sliding joint elements at yield under dynamic impact loading (simulating a burst). Significant joint element heating and mechanical sparking was observed during the testing of arching yielding support frame sliding joints and straight friction prop joints as a result of friction at yield. Some of the aspects defined in standard PN-EN ISO80079-36:2016 include the maximum temperature T max =150°C for a surface that can accumulate a layer of coal dust. Tests of the friction joints have shown that during impact loading, numerous mechanical sparks are produced at the friction joints of sections of the steel prop, with the surface temperature of the sections starting from 169.6°C and reaching up to 234.1°C. During tests it was also to determined emissivites of the tested sliding joints constructed from V29-V32 secrions depending on corrosion products which consist in range 0.842–0.873. Such a high temperature can initiate an explosive mixture consisting of methane, air and coal dust.

Investigation of impact behavior of glulam beam strengthened with CFRP

This study’s objective is to examine the general behavior of glulam timber beams strengthened with CFRP (Carbon Fiber Reinforced Polymers) strips and ascertain the impacts of the applied strengthening technique on the performance of timber beams under the influence of rapid dynamic impact loading. In the study, the innovative strengthening method developed with CFRP strips was placed on the lower tensile surface of glulam timber beams and positioned as more than one layer between laminated beam parts. In addition, placing CFRP fan-type anchors on the endpoints of the strips to delay the debonding of CFRP strips from the surface is an innovative application examined in this study that contributes to the literature. The glulam timber beams that strengthened with the developed method and non-strengthened reference test specimens were tested with the free-weight drop test setup. The acceleration, displacement, strain at the tensile surface, and the variations of the applied impact loading by the time were measured and interpreted. In this way, the performance level of the strengthening technique under the effect of the impact loading was investigated. The glulam timber beams strengthened with CFRP strips are modeled using ABAQUS finite element software to compare the numerical analysis with the experimental results and determine the extent to which the numerical analysis might produce realistic results.

Damage Evolution and Constitutive Model of Marble under Dynamic Loading

Through the application of SHPB (split Hopkinson pressure bar) test, the failure mode and dynamic stress-strain curves of marble samples were obtained. The dynamic constitutive model of marble was established with the fracture mechanical parameters (brittleness index), and the calculated curves were compared with the experimental curves. The evolution characteristic of damage variable D was analyzed. The results show that there are three main stages of marble deformation under dynamic impact load, which are linear elastic deformation stage, crack growth stage, and macroscopic failure stage. The sample shows obvious brittleness in the macroscopic failure stage. It is found that with the increase of strain rate, the degree of damage is getting worse. The stress-strain curves obtained based on the constitutive model are in good agreement with the experimental curves. The damage variable D can theoretically explain the evolution law of macroscopic failure of the sample. To some extent, there is a mechanism inside the rock to regulate the damage development of the rock, and the final failure degree of rock sample depends on △ σ BC and ε b .

Analysis of fluid dynamic behavior and impact load on oblique water entry of a two-dimensional seaplane based on VOF method

Seaplane landing is a typical water entry impact phenomenon. However, our understanding on the development of jet flow and air cavity, and corresponding load characteristic is still limited. In this paper, the impact problem of oblique water entry of a two-dimensional seaplane is studied to clarify the relationship between theses complex flows and loads. A gas-liquid two-phase model is established to model these complex fluid flows, where the air-water interface is captured based on a VOF algorithm. The accuracy is validated by the published experimental data. Some hydrodynamic impact characteristics related to seaplane model under different oblique water entry postures, including air-water free surface and local impact pressure are discussed. Complicated flows (air cavity and jet flow impact) are the internal cause to some unusual load characteristics such as multiple pressure peaks, negative pressure, simultaneity of impact load on the airfoil, and great difference of load at different positions on the cabin. The evolution of jet flow and air cavity is further discussed through combing free surface and pressure distribution. Results clarified the mechanism of complex flows under the influence of bottom cabin and inclined postures, which will be helpful to further understand the impact phenomenon of seaplane landing.

Unmanned aerial vehicle strike on a flat plate: Tests and numerical simulations

The incursion of Unmanned Aerial Vehicles (UAVs) into airports often occurs due to the popularity of drones, which may lead to a threat to aircraft flight safety. Therefore, estimating the dynamic impact load caused by drone strikes is essential. This paper proposes a test method with high precision and low cost involving launching of a UAV to impact a flat plate specimen by using an air gun. The test results of UAVs impacting flat plates at different impact velocities, such as the UAV damage deformation captured by a high-speed camera and strain vs time dynamic response curves of plates, were obtained and analysed. At the same time, a corresponding numerical simulation was carried out by using the explicit finite element software LS-DYNA. The predicted damage to the UAV and strain on the flat plate during the strike process were compared with the test results. The overall trend of the simulation results is in good agreement with the test results, at least for the first three milliseconds of the event. This shows that the numerical simulation model established in this paper is reasonable. The UAV numerical method established in the present paper can be used to carry out numerical simulations and evaluations of the collision safety of UAVs against large aircraft and high-value ground targets. The results show that the local deformation of the impacted target is uneven due to the distribution of concentrated mass components such as motors, battery, and camera. As the impact velocity of the UAV increases, all parts of the UAV are seriously damaged and basically in a fragmented state, and the battery is greatly deformed. The interaction between the UAV and the flat plate specimen is approximately 2.7 ms, and the UAV numerical simulation model established in this paper can well simulate the real UAV impact process.

Multibody dynamics modelling of a 6-axle truck to quantify the effects of pavement and vehicle parameters on dynamic loads

ABSTRACT The actual service life of the pavement is related to dynamic tire loads. To accurately calculate dynamic loads, a multibody dynamics model of a 6-axle heavy truck was developed. The difference between simulated and experimental RMS values of wheel centre force and acceleration was within 15%. Based on the validated dynamics model, the effects of ride quality index (RQI), vehicle speed, load capacity, and suspension damping coefficient on dynamic impact factor (DI) and dynamic load amplitude (DLA) were explored. When the vehicle was fully loaded, both DI and DLA increased with decreasing RQI, increasing vehicle speed, and increasing suspension damping coefficient. Among them, the effect of RQI and vehicle speed on DLA and DI was much greater than that of suspension damping factor. In addition, the dispersion of DI values for each axle increased as the vehicle mass decreased. Therefore, it is necessary to consider the combined effects of RQI, vehicle speed and load capacity when applying dynamic tire loads in pavement design or life estimation. The procedure in this paper facilitates the accurate calculation of dynamic loads for different pavement and vehicle parameters and is recommended to be used in vehicle-pavement coupled analysis.