Drop Hammer Impact Research Articles

Dynamic response and energy absorption of aluminum foam sandwich under low-velocity impact

Aluminum foam sandwich (AFS) are widely used in energy absorption because of their light weight and excellent energy dissipation capabilities. In this study, energy absorption, deformation modes, and dynamic response of AFS under low-velocity impact are investigated using experimental and numerical approaches. Dynamic impact tests are performed utilizing a drop hammer impact test on AFS with different core densities, face sheet thicknesses, and impact energy. Based on the 3D Voronoi foam model, a full-scale finite element model (FEM) is developed to simulate the mechanical response of AFS under low-velocity impact, and verified by experimental results. The contributions of different AFS components to energy absorption at various impact velocities are further analyzed, along with the effects of face sheet thickness distribution. The results indicate that the performance of the face sheet and core and the impact energy have a remarkable influence on the low-velocity impact response and damage modes of the AFS. The type of structure configuration, “thin top and thick bottom,” enables the AFS better play its energy absorption while ensuring the overall light weight. This study provides a reference for the design and optimization of the face sheet thickness of AFS when it is used as an energy-absorbing member and improves their design efficiency.

Deformation failure and acoustic emission response characteristics of water-containing concrete under impact load

Concrete materials are widely used in construction projects. Many concrete structures are in an aqueous environment and subjected to impact loads. Under this condition, the mechanical properties and failure modes of concrete will change significantly. In this paper, the drop hammer impact failure experiment of water-containing concrete was established. The deformation and failure characteristics as well as acoustic emission response law of concrete under dynamic load with different immersion time were studied. The failure mechanism and acoustic emission response precursor characteristics of concrete under drop hammer impact were revealed. The results show that the peak impact force of concrete was exponentially related to the immersion time. Its failure cracks were mainly distributed on the diagonal of the impact surface and the central axis of the observation surface. Due to the dual effect of water on the dynamic mechanical properties of concrete, the cracks and damage degree of concrete increased first and then decreased with the increase of immersion time. The peak acoustic emission (AE) count was exponentially related to the immersion time. The acoustic emission “quiet period” could be used as one of the precursor characteristics of concrete instability and failure, and the “quiet period” gradually became shorter with the increase of immersion time. This research results are of great significance for evaluating the stability of concrete structures and warning of concrete impact damage.

Dynamic fracture toughness measurement of graphite material considering inertial effect

Graphite materials are widely used as moderators, reflectors, and core structural materials in high-temperature gas-cooled reactors. During operation, graphite materials in nuclear reactors may be subjected to dynamic loads caused by earthquakes or other factors. Therefore, the dynamic fracture properties of graphite materials need to be investigated. In this study, dynamic three-point bending drop hammer impact experiments were conducted on IG-11 graphite specimens with precracks to measure their dynamic fracture toughness under medium- and low-speed impacts using a digital image correlation method. Traditional methods for measuring fracture toughness based on ASTM standards do not consider the influence of the inertial effect, leading to unreasonably large measurement results. To address this disadvantage, the dynamic fracture toughness of IG-11 graphite was evaluated using a spring–mass model that considers the inertial effects of materials. Results indicated that the measured fracture toughness was significantly lower than that obtained based on the ASTM standard and increased almost linearly with increasing impact velocity. The toughening mechanism was analysed by observing the fracture morphology of the samples using a scanning electron microscope. The results showed that as the impact velocity increased, the fracture mode of the graphite samples gradually changed from intergranular to transgranular fracture, and the samples absorbed sufficient energy, resulting in a noticeable toughening phenomenon.

Optimizing rock breaking performance: The influence of chamfer on polycrystalline diamond compact (PDC) cutters

Research on the rock-breaking performance of the Polycrystalline Diamond Compact (PDC) cutter has primarily focused on sharp cutters, often overlooking the influence of chamfer. Notably, the design of chamfer parameters has been largely unreported. In this study, we established a theoretical model of cutting force that takes chamfer into account. We analysed the primary and secondary relationships of four factors – back rake angle, depth of cut, chamfer angle, and chamfer length – on the force of the PDC cutter. This was done through a pseudo-level orthogonal level test. A numerical simulation, based on the Smooth Particle Hydrodynamic (SPH) method, was conducted to analyse the rock-breaking force and stress distribution characteristics of PDC cutters with different chamfer angles. Combined with a drop hammer impact test, we provided an optimized design of chamfer parameters. Our findings revealed that while the chamfer had a relatively minor influence on the force of the PDC cutter, it contributed to the optimal distribution of stress on the PDC cutter. This effectively protected the cutting edge and prevented early cracks and spalls of the cutter. When the chamfer angle was less than or equal to the back rake angle, the resultant force of the PDC cutter increased with the increase of the chamfer angle. However, when the chamfer angle was greater than the back rake angle, the resultant force of the PDC cutter first increased and then slightly decreased with the increase of the chamfer angle. Additionally, the resultant force of the PDC cutter increased approximately linearly with the increase of chamfer length. When the chamfer angle of the PDC cutter was between 30° and 45°, the fluctuation of the cutting force was relatively smooth, the rock-breaking process was stable, and the cutter’s impact resistance energy was relatively higher. These findings will provide valuable guidelines for the design of chamfered PDC cutters.

Numerical analysis of dynamic collapse response of beam–column substructures under impact loads

To investigate the collapse resistance performance of steel-frame structures at varying scale ratios, numerical simulations were performed to scrutinize the influence of different scale ratios on the dynamic response of beam–column substructures subjected to impact loads. In this study, two drop-hammer impact tests were modeled and simulated, their results were compared, and the accuracy of the finite element modeling method was verified. Concurrently, a detailed model of a double half-span beam–column substructure was established to examine the effect of impact energy variations (altering the mass and velocity of the drop hammer) on the structural impact force and vertical displacement. This study analyzed variations in the impact force, impact time history, vertical displacement, internal forces, and energy absorption for models with different scale ratios when altering the impact energy. Finite element analysis results indicated that the impact velocity of the drop hammer affected the peak impact force of the substructure, whereas the drop-hammer mass influenced the force plateau and impact duration. Both the impact duration and maximum vertical displacement were positively correlated with the impact of the drop hammer and were approximately linearly positively correlated with the impact kinetic energy, resulting in the establishment of a linear fitting model between the maximum vertical displacement and the impact energy. For scaled-down substructures, variations in the impact energy could be achieved by adjusting the drop-hammer impact velocity (drop height). A proposed scale ratio for the substructure drop-hammer impact anti-collapse test is provided.

Experimental investigation on the dynamic response of half steel-concrete composite slabs under low-velocity impact

The current research on the dynamic response of half steel–concrete (HSC) composite slabs is not only limited but also primarily concentrated on high-velocity impacts. This study investigates the dynamic response of such structures by examining failure modes, impact resistance mechanisms, and energy dissipation under low-velocity impacts through drop hammer impact tests conducted on five HSC specimens. In addition, the variation of the out-of-plane residual bearing capacity with the damage degree of specimens and impact energy is analyzed using static loading tests. Finally, the dynamic response differences between half steel–concrete slabs and steel–concrete (SC) slabs are analyzed by comparing multiple indicators. The results indicate that HSC slabs exhibit five distinct failure modes when subjected to low-velocity impact within a range of 3.13–7.00 m/s. Additionally, five stages of the dynamic response process of the HSC slabs are proposed. Moreover, the bottom steel plate plays a crucial role in retaining structural out-of-plane residual bearing capacity. Furthermore, compared with the SC structure, the HSC slab is capable of absorbing input impact energy within a much smaller displacement.

The study on the influence of different damage introduction methods on the damage characteristics of aircraft composites

Composite materials have advantages incomparable to traditional metal materials. However, they are more sensitive to impact damage and their mechanical properties decrease significantly after impact damage. Therefore, it is of great significance to study the energy absorption, mechanical response and damage mechanism of materials in different ways. To study the influence of different punch diameter sizes on the material damage characteristics, three kinds of punch diameters of 12.7 mm, 16 mm and 25.4 mm are selected to carry out the quasistatic indentation test and drop hammer impact damage test on the test pieces respectively. The material damage caused by different punch sizes under two damage introduction methods is analyzed. Damage introduction was carried out on the test piece with the same layering through two methods: quasi-static indentation and drop hammer impact. The damage depth, damage area and residual strength were compared after damage introduction. The difference between quasistatic indentation and drop hammer impact damage introduction was verified by comparing the damage characteristics to each other. The results show that with the increase of punch diameter size, the damage area decreases and the residual strength of the material increases. In addition, the test results of different punch diameter sizes under the two damage introduction methods have the same change trend, which proves that the impact of punch size on the material damage characteristics has no obvious relationship with the damage introduction method. Quasi-static indentation and drop hammer impact damage have no significant difference in the residual strength of materials after damage, which verifies the equivalence of static indentation and damage introduction.

Studies on the life, damage evolution, and crack propagation behaviors of TC18 titanium alloy under repeated impact loading

TC18 titanium alloy has been widely used as the key structure which is often subjected to repeated impacts in service in aerospace engineering. In this study, the repeated impact responses of TC18 were investigated by conducting various repeated drop hammer impact tests. Abundant microscopic characterization technologies were used to reveal the correlation between damage evolution and the impact response. The results show that the average impact fatigue life (Nf¯) of the notched three-point-bend specimen decreases exponentially with the impact energy. Microscopic observation shows that cracks nucleate at the initial 40%∼50% of Nf¯, then propagate steadily during the next 50% to 90% of Nf¯. During the last 10% of Nf¯, the cracks propagate rapidly, resulting in the failure. During crack propagation, the repeated impacts induce complex stress states in the vicinity of cracks, leading to grain refinement, phase transition, and strengthened texture. The phase transition and strengthened texture mechanisms are mainly due to the generation of the platelet-like α subgrains inside the refined grains. The results in this paper are crucial for understanding the microscopic damage and failure mechanism of TC18 under repeated impacts, which helps to establish the damage accumulation-based life prediction model in the future.

An experimental and numerical study on the hybrid effect of basalt fiber and polypropylene fiber on the impact toughness of fiber reinforced concrete

As the civil aviation industry advances, higher requirements are put forward for the performance of airport cement pavement. The frequent takeoffs and landing of aircraft will cause continuous and large impact load on airport pavement, and combined with long-term natural factors, there will be various structural diseases. These diseases not only affect the service life of pavement, navigation safety. To enhance the impact resistance and durability of concrete, the incorporation of fiber has proven an effective approach, and basalt fibers (BF) and polypropylene fibers (PF) are selected as reinforcement materials in this study. Firstly, the effects of single BF and hybrid BF and PF on the mechanical properties of concrete were explored through compressive and flexural tests considering fiber volume contents (0.1%, 0.15, 0.2%) and lengths (6 mm, 9 mm, 12 mm). Then, the drop hammer impact test method, recommended by ACI committee 544, was refined to evaluate the impact resistance toughness of concrete. Finally, the numerical simulation of the impact test was established to explain the concrete impact damage mechanism. The results show that under less than 0.15% volume content, the single BF can effectively enhance the compressive strength, flexural strength, and impact resistance of concrete. Compared with the single BF, the combination of 12 mm BF and 6 mm PF yields favorable results, encompassing improved mechanical properties and impact resistance, thus exhibiting a positive hybrid effect. The increase in PF length (9 mm) leads to a reduction in compressive strength but an improvement in flexural strength and impact resistance. The simulation of the impact test is constructed and the accuracy is confirmed by comparing the impact times and failure patterns of the specimens. The tensile damage of plain concrete is much greater than the compressive damage, and the cracks will spread rapidly from the upper surface to the lower surface. Compared with plain concrete, the crack width of hybrid fiber reinforced concrete is larger, but the damage degree is more uniform. Fiber can absorb a large amount of impact energy, reduce the emergence of micro-cracks, and improve the impact toughness and toughness coefficient of concrete.

Experimental investigation on dynamic response behavior of PC beam-column sub-assemblages under middle-joint drop-weight loading

The dynamic response of frame structure in progressive collapse has been investigated by some scholars by removing the column suddenly. However, the research cannot exhibit the effect of blast load on the dynamic response of the structure. Especially in a close-field explosion, a large axial tension force may occur in the cross-section of the column suffered from the blast load directly. It is the main factor causing dynamic response and subsequently leading to progressive collapse. This paper experimentally studied the dynamic response behavior of prestressed precast concrete sub-assemblage (PCS) through middle-joint drop-weight loading, and the tension force caused by the failed column was applied downward on the top of the middle joint of sub-assemblage through drop hammer impact. The same loading condition was also applied to the reinforced concrete sub-assemblage (RCS) to compare the dynamic response behavior. The results showed that all the sub-assemblages exhibited flexural damage mode. Compared with RCS, more serious damage occurred concentratedly at the beam-column interface in PCS, but no prompt damage appeared in the beams. The sub-assemblage went through local dynamic response and global dynamic response stages in succession. Reverse arch action (RAA) emerged during the local response stage due to the pronounced inertial action at the middle joint, and it became more significant with increasing impact velocity. Compared with RCS, the pretension of steel strands may enhance the effect of RAA in PCS. Compressive arch action (CAA) emerged during the global response stage with the energy transferring from the kinetic energy to strain energy when middle joint displacement (MJD) increased continuously. With increase of impact velocity, the contribution of steel strands tension in resisting collapse increased significantly. The damage mode of the beam end in PCS at the peak MJD was almost the same as that under quasi-static loading at the same MJD, and the strain energy was also approximately identical to that under quasi-static loading. Based on the premise of flexural damage mode of PCS, the peak MJD can be determined according to the vertical resistance of PCS under pushdown loading using the work-energy principle.

Study on Dynamic Mechanics of Node-Enhanced Graded Lattice Structure and Application Optimization in Automobile Energy Absorbing Box.

Based on the lightweight characteristics of automotive energy absorption boxes and the requirement of good energy absorption effect, this article first applies the node-enhanced body centered cubic (NBCC) lattice structure to the inner core design of automotive energy absorption boxes. The gradient study of the NBCC lattice structure was carried out using a drop hammer impact and split Hopkinson pressure bar (SHPB). The results indicate that gradient lattice structures have advantages in energy absorption, but there are differences under different gradient strategies. When the impact is not sufficient to compact the structure, the vertical rod diameter gradient node-enhanced lattice structure (RGNBCC) can absorb more energy and improve energy absorption performance by 25%. The vertical height gradient node-enhanced lattice structure (HGNBCC) is more suitable for high-speed impact conditions. Based on the advantages of the RGNBCC in resisting low-speed impacts, it is applied to the inner core design of automotive energy absorption boxes and optimized using multi-objective optimization methods. The optimization results show that the maximum peak impact force is reduced by 45.6% and the specific energy absorption is increased by 30.4%.

Low-Speed Impact and Residual Mechanical Performance of the BR1200HS/AA6082 Self-Piercing Riveted Joints

To investigate the low-speed impact response of the BR1200HS steel and AA6082 aluminum alloy self-piercing riveted (SPR) joint, low-speed impact tests with impact energies of 2.5 J, 5.0 J, 7.5 J, 10.0 J, 12.5 J, 15.0 J, 20.0 J, and 30.0 J were conducted utilizing a drop hammer impact tester. The results show that with the increased impact energy, the visual breakages of the SPR joints become more severe. The maximum impact energy the joints can sustain ranges from 10.0 J to 12.5 J. When the impact energy is less than 12.5 J, the contact force/energy–time curves show similar variations. Moreover, as the impact energy increases, total uptake energy value (Et), maximum uptake energy value (Ef), and maximum contact force (Fm) of the joints increase gradually. The low-speed impact energy has little effect on the maximum static tensile force of the impacted joints. However, the residual energy values decrease with the increase in impact energy. The tensile failure form of the joints is the pulling out of the rivets from the lower plates, and the low-speed impacts have no significant effect on the tensile failure form of the joints.

Effect of global stiffness on the force response of thin GFRP reinforced concrete slabs subjected to impact loading

The purpose of present study is to investigate the effect of global stiffness on the force response of thin GFRP reinforced concrete slabs simply supported by steel beams under drop-weight impact. Considering the strain rate effect of GFRP bars and concrete materials, a numerical model of GFRP-RC slabs was established and verified. The dynamic equilibrium relationship of the impact force, reaction force and inertial force was analyzed and intuitively explained from the velocity and displacement. Meanwhile, the effects of the global stiffness by varying the slab length, slab thickness and reinforcement ratio on the acceleration distribution, characteristic value of impact force and reaction force, failure pattern, displacement distribution and energy dissipation were evaluated in more detail. Eventually, the semi-empirical formulas considering key parameters were proposed to predict the reaction force time history of simply-supported RC/FRP-RC slabs under drop hammer impact. The results show that the effect of the slab stiffness by varying the slab length and thickness on the reaction force is significant, while the influence of reinforcement ratio is not obvious. The effect of global stiffness of the slab on the plateau value of the reaction force is similar to that on the plateau value of the impact force. The effect of the slab stiffness by varying the slab thickness and reinforcement ratio on the displacement is obvious, while varying the slab length hardly affects the deformation. The fitting equation considering key parameters can predict the simplified reaction force time history of simply-supported RC/FRP-RC slabs under impact loading. However, more experimental validation and extensive parametric studies are needed to improve their accuracy and applicability.

On Design of Through-Hole Structure Inspired by Vascular Bundle of Bamboo for Multiple Compression Load Cases

In this paper, the multiangle’s crashworthiness of the bionic tubes inspired by the cylindrical fibers of bamboo vascular bundles as well as the through-hole structure are studied. A finite element model validated by the theoretical analysis and drop hammer impact experiments is used to assess the optimal core distribution ratio of the bionic tube at 0°, 10°, 20°, and 30° impacts. Finally the effects of the number of circular core and wall thickness on crashworthiness are investigated. The results show that the bionic tube has better crashworthiness at small angle impacts compared to the square tubes, and l14r6 is obtained as the optimum bionic tube: the SEA at small angles improves by 12.72% (0°), 14.91% (10°), and 18.12% (20°), respectively; however, the SEA at 30° impact decreases by 2.53%. As the number of circular core increases, the crashworthiness becomes more significant, but the deformation mode becomes worse. The SEA of the tube with 32 cores increases by an average of 1.85 times (0°), 1.89 times (10°), 1.34 times (20°), and 1.41 times (30°) for each impact condition, respectively, compared to the tube with single core.

Performance of steel–concrete composite walls with recycled aggregate concrete under low-velocity lateral impact loading

This paper investigates the impact-resistant behaviours of steel–concrete (SC) composite walls experimentally and numerically, which consist of two outer steel plates and infilled recycled aggregate concrete (RAC). Totally eight SC walls were designed and fabricated with different coarse recycled aggregate (CRA) content and steel plate thicknesses. Drop-hammer impact testing was first performed to obtain the failure mode, impact force and deformation. Test results indicated that the impact resistance behaviour of SC walls enhanced considerably with a decrease in CRA content. The tie bars combined with studs were effective to avoid the separation of steel plate from the concrete core. Afterwards, the finite element (FE) models were developed and calibrated, and then used to obtain more information on the full-range motion response, development of stress and strain, and energy absorption. In addition, the influences of different parameters, including the CRA content, material strength, steel plate ratio, tie-bar spacing, impact energy and axial load ratio on the impact resistance performance were assessed. Finally, the displacement response of SC composite walls with RAC was predicted using single-degree of freedom (SDOF) approach.

Experimental study on infrared thermal response characteristics of water-bearing concrete under drop hammer impact

The dynamic impact damage of concrete will lead to serious safety accidents, and the water environment will aggravate the degree of damage. In this paper, an infrared monitoring experimental system for drop hammer impact damage of water-bearing concrete was designed and established. The mechanical properties, infrared radiation temperature (IRT) and infrared thermography of concrete impact damage with different soak time were tested and analyzed. The influence of water on the infrared generation mechanism of concrete was discussed. The results show that water has an initial weakening effect on concrete, which weakens the cementation between concrete particles and aggregate strength, resulting in a decrease in concrete strength. Compared with dry concrete, the infrared temperature of water-bearing concrete increased more during impact damage. With the increase of soak time, the average infrared temperature (AIRT) and the maximum infrared temperature (MIRT) of water-bearing concrete decreased. When dry concrete was damaged, tensile cracks were mainly produced and accompanied by heat absorption. When water-bearing concrete was damaged, high temperature shear cracks appeared. The high temperature generated at the moment of impact failure of water-bearing concrete may be caused by the cavitation phenomenon of water in the microscopic pores of concrete during the drop hammer impact and the combined effect of concrete microstructure damage. The research results are of great significance for monitoring and evaluating the stability of the dynamic evolution process of concrete structures.

Study on Impact Resistance of All-Lightweight Concrete Columns Based on Steel Fiber Reinforced and Various Axial Compression Ratio

Concrete columns in service are exposed to threats such as accidental impacts and explosions, which pose potential risks to the safety of buildings. Although fully lightweight concrete elements prepared from non-sintered fly ash ceramic pellets and pottery sand are widely used in engineering practice, the dynamic response of such elements under impact loading is not supported by adequate research data. Therefore, in this study, the dynamic response of all-lightweight concrete columns under impact loading with different axial compression ratios (0.1, 0.2, and 0.3) was investigated by means of drop hammer impact tests, and the potential of shear wave steel fibers in mitigating structural damage and preventing structural failure was investigated. The results of the study reveal that the specimens primarily exhibit shear and bending damage under impact loading. With an axial compression ratio of 0.1, the specimen is dominated by bending damage. As the axial compression ratio increases from 0.1 to 0.3, the specimen’s damage mode transitions to shear damage dominance. This change results in a larger impact force and displacement response while experiencing lower displacement acceleration. Additionally, the introduction of steel fibers improves the strength and stiffness of the specimens, shifting their behavior from shear to bending damage. Consequently, this reduces impact damage, mid-span displacement, and displacement acceleration while enhancing the specimen’s response to the impact force and its capacity for deformation energy dissipation.

Experimental study on impact toughness of multi-combination hybrid fiber-reinforced magnesium phosphate cement-based materials

In order to improve the brittleness of magnesium phosphate cement-based materials (MPC) and overcome the limitations of single fiber-reinforced cement-based materials, this study investigated the mechanical properties of hybrid fiber-reinforced magnesium phosphate cement-based composite materials (HFRMPC) by incorporating four types of fibers: hooked-end steel fiber (HSF), micro steel fiber (MSF), polyvinyl alcohol fiber (PVAF), and basalt fiber (BF). Cylindrical specimens were prepared by single and double hybridization of the fibers and subjected to drop hammer impact tests to analyze the effects of different fiber hybridization methods on the impact resistance of these materials. The two-parameter Weibull distribution was used to analyze the test results to predict failure probabilities and to investigate the fiber reinforcement and toughening mechanisms in MPC through microscopic structural analysis. The results showed that the impact resistance of the fiber hybridization group was much better than that of the single fiber group, and the impact resistance increased continuously with increasing fiber content. The fibers' impact resistance enhancement effects were in the following order: MSF > PVAF > BF. The fiber combination methods were ranked as follows from best to worst: HSF + PVAF > HSF + BF > HSF + MSF > PVAF + BF. The 1.5% HSF+0.6% PVAF hybridization had the best impact resistance performance, with an increase in initial cracking and impact energy dissipation at the failure of 7748.6% and 8921.2%, respectively, compared to the M0. The probability distribution of impact number of initial cracking (N1) and failure (N2) of the specimens followed the double-parameter Weibull distribution well. The multiscale strengthening and toughening zone composed of fibers with different geometric dimensions and elastic modulus was crucial to the material's performance, as the fibers acted in progressive briding under external impact loads, dissipating impact energy through the failure morphology of pull-out and breaking, significantly improving the HFRMPC's impact toughness. A comprehensive evaluation of the four indicators of impact resistance and manufacturing costs for various hybrid fiber compositions found that the combination of 1.5% HSF and 0.6% PVAF exhibits the most outstanding overall performance.

Transverse impact behavior of concrete filled steel tube simply supported members stiffened with encased I-shape CFRP

Concrete-filled steel tubular simply supported members stiffened with encased I-shaped CFRP (CFSTS-CFRP members) have been developed due to their excellent mechanical performance, promoting promising applications in bridge and building structures. However, these members are susceptible to collision impacts during service, leading to serious accidents. This paper aims to investigate the structural behavior of CFSTS-CFRP members subjected to transverse impact loading, utilizing experimental, numerical, and theoretical studies. Drop hammer impact tests were conducted on three CFSTS-CFRP specimens with varying impact velocities, while a CFST specimen was used as the benchmark. The experimental results demonstrate that all CFSTS-CFRP specimens experienced bending failure. The cooperation between the I-shaped CFRP and CFST members was observed, with the mechanical properties of CFSTS-CFRP specimens being fully utilized. The working mechanism of CFSTS-CFRP members is revealed by numerical simulation results obtained from the FE models of the tested CFSTS-CFRP members, which consist of the analyses of failure mode, inertia force, sectional moment, energy absorption, etc. Furthermore, by investigating the effects of different parameters on the structural response of CFSTS-CFRP members, predicted models for dynamic flexural capacity and maximum deflection are proposed for the purpose of impact design. Additionally, the contribution of the steel tube, concrete, and I-shaped CFRP to the transverse impact resistance of CFSTS-CFRP members is clarified. This clarification provides a scientific basis for determining the respective weight coefficients in subsequent damage assessment research. The findings from the experimental, numerical, and theoretical analyses contribute to the understanding of their mechanical performance and assist in the development of more efficient design approaches.

Plastic Response and Failure of the Cruciform Structure under In-Plane Load

In this study, a common cruciform structure in ship hulls was designed and experimented with in order to analyze its deformation characteristics under planar collision and quasi-static loading. The mechanical parameters of the materials were determined by performing tensile tests on the plates used in the specimens. The applicability of the EPS, BWH, and RTCL failure criteria in the simulation of compressive structures was investigated by finite element simulation of quasi-static tests and falling weight impact tests. The effects of mesh size on the deformation and impact force of the cruciform structure under plane loading were comparatively analyzed. The results show that under plane loading, the cruciform structure undergoes axial compression deformation first, followed by buckling and wrinkling deformation. Compared with the quasi-static test, the drop hammer impact test showed higher deformation concentration and smaller wrinkle height. Under the same axial deformation condition, the structural resistance of the drop hammer impact test was about 13% higher than that of the quasi-static test. It is worth noting that the RTCL failure criterion is effective in modeling the failure of compressive structures in simulations with structures with different compressive deformations.