Strain Rate Response Research Articles

Neural network based rate- and temperature-dependent Hosford–Coulomb fracture initiation model

The accurate description of the strain rate and temperature dependent response of metals is a perpetual quest in crashworthiness and forming applications. In the present study, experiments are carried out to probe the onset of ductile fracture for an aluminum alloy AA7075-T6 for 136 combinations of stress state, strain rate and temperature. The experimental campaign covers strain rates ranging from 0.001/s to 100/s, and temperatures ranging from 20 °C to 360 °C. We combine a YLD2000 yield surface with a neural network based hardening law to describe the large deformation plasticity response of the material. The NN-based hardening law is trained on experimental data, achieving 3.9% accuracy on force predictions including the post-necking regime. The loading paths to fracture are extracted for each simulation, showcasing non-proportionally evolving stress triaxiality, Lode angle parameter, strain rate and temperature. A neural network parameterized Hosford–Coulomb fracture locus is proposed, which is trainable using these evolving loading histories. The accuracy of the proposed fracture model is validated against the experimental onset of fracture, predicting the fracture onset at an error of 8%.

A large deformation model for quasi-static to high strain rate response of a rate-stiffening soft polymer

Polyborosiloxane (PBS) is an important rate-stiffening soft polymer with dynamic, reversible crosslinks used in applications ranging from self-healing sensing and actuation to body and structural protection. Its highly rate-dependent response, especially for impact-mitigating structures, is important. However, the large strain response of PBS has not been characterized over quasi-static to high strain rates. Currently, there are no constitutive models that can predict the strongly rate-dependent large-deformation elastic-viscoplastic response of PBS. To address this gap, we have developed a microstructural physics motivated constitutive model for PBS, similar soft polymers and polymer gels with dynamic crosslinks to predict their large strain, non-linear loading–unloading, and significantly rate-dependent response. We have conducted compression experiments on PBS up to true strains of ∼125% and over a wide strain rate range of 10−3 s−1 to 103 s−1. The proposed semi-physical model fairly accurately captures the response of PBS over six decades of strain rates. We propose boron–oxygen coordinate-bond dynamic crosslinks with macroscopic relaxation timescale τ≈3 s and temporary entanglement lockups at high strain rates acting as crosslinks with τ≈0.0005 s as the two types of crosslink network mechanisms in PBS. We have outlined a numerical update procedure to evaluate the convolution-like time integrals arising from dynamic crosslink kinetics. Experiments involving three-dimensional inhomogeneous deformations were used to verify the predictive capabilities of our model and its finite element implementation. The modeling framework can be adopted for other dynamically crosslinked rate-stiffening soft polymers and polymer gels that are microstructurally similar to PBS.

Experimental and numerical studies on pulse shaping techniques used in split Hopkinson pressure bar for testing concrete material

Split Hopkinson pressure bar (SHPB) is commonly used to characterise materials under high strain rates. However, conventional SHPB tests on brittle materials have encountered several experimental challenges for high strain rate loading. In relatively brittle materials like concrete, the deformation of the specimen is very small when subjected to impact loading; hence, it is very difficult to obtain the prerequisites of valid SHPB tests such as dynamic equilibrium and constant strain rate in the specimen. To overcome these issues, the current study presents the importance of the pulse shaper approach in SHPB application for the dynamic characterisation of concrete material. Selection of the appropriate dimension of pulse shaper assists in facilitating dynamic stress equilibrium and constant strain rate in the specimen. In the present study, copper pulse shapers are used for the evaluation of concrete under high strain rate loading using an SHPB set-up. Parameters such as the effect of dimensions (diameter and thickness) of pulse shapers on loading pulses, dynamic equilibrium, constant strain rate and material responses are studied. Experimental results reveal the prediction of suitable pulse shapers for 50–200/s strain rates. In addition, numerical simulation is also performed and results are validated with the experimental data.

Geomechanical Modeling of Fracture-Induced Vertical Strain Measured by Distributed Fiber-Optic Strain Sensing

Summary Distributed acoustic sensing (DAS) has recently gained importance in monitoring hydraulic fracturing treatments in the oil and gas industry. DAS data contain critical information about the fracture geometry as linearly relatable induced strain variations during the stimulation. The low-frequency components of the DAS (LF-DAS) data are known for their complexity as they exhibit various characteristic signals—caused by several mechanisms—that complicate their interpretation. LF-DAS data from horizontal monitoring wells (HMWs) have been used to detect fracture hits and characterize fracture geometry. However, the LF-DAS data from vertical monitoring wells (VMWs) have not been studied extensively as a means to infer fracture geometry. The major limitation of VMWs is the number of monitored stages, but the data contain more information about fracture height compared with LF-DAS measurements from HMWs. Hence, it is necessary to have a physical rock deformation model to simulate the strain rate responses in offset VMWs during fracture propagation to understand and interpret the various patterns that are observed in the field data sets. The objective of this study is to simulate strain rate signals in VMWs during hydraulic fracturing and to analyze the measurements to obtain information on the fracture geometry, especially the fracture height. The fracture boundary can be directly related to the strain rate signals. In this study, we propose a workflow to determine fracture height at different fiber-to-fracture (dff) distances for fracture heights ranging from 20 m to 300 m. We conduct a detailed sensitivity analysis to understand the impacts of the dff, the perforation location, the fracture passing time, and the well inclinations on the measured strain rate signals. The analysis helps interpret the various patterns observed in field data and the underlying mechanisms. Interpretation of field data from the Hydraulic Fracture Testing Site 2 (HFTS-2) using the results from our forward physical model provides valuable information on the fracture characteristics that can be captured by the physical model. The results of this study are expected to provide better interpretations of LF-DAS signals from VMWs.

Assessment of a high strength concrete using experimental and numerical methodologies for high strain rate ballistic impacts

The high compressive strength of concrete materials enables it to be implemented for many applications. Understanding its response under high strain rate loadings is especially important for some of these applications. This study investigates the high strain rate response of a high-performance concrete denoted as BBR9 under ballistic impact. This is conducted through both an experimentally and numerically based methodology. BBR9 targets are impacted with a spherical projectile at velocities ranging from 432 to 1459 m/s and three target thicknesses ranging from 25.4 to 58.1 mm. These impacts are studied numerically by formulating a finite element model corresponding to the experimental design in this study. The mechanical response of the concrete target is captured using the Holmquist-Johnson-Cook (HJC) concrete model with its parameters calibrated to confined compressive experiments of the BBR9 concrete. The simulations show good agreement with the kinetic experimental data with an average error across all simulation points of approximately 5%, thereby validating the HJC model for this concrete in these high strain rate loading applications.

An enhanced data-driven constitutive model for predicting strain-rate and temperature dependent mechanical response of elastoplastic materials

Data-driven and machine-learning based approaches provide a highly compatible and efficient fundamentals for the mechanical constitutive modeling of engineering materials. In this work, an enhanced data-driven constitutive model is developed to predict the stress–strain relationship of an elastoplastic material through the integration of a data-driven concept with fundamental plasticity theory. A novel strain reconfiguration strategy is proposed to improve the learning capability and predictability of the data-driven model, along with a two-step training method. A compatible numerical implementation algorithm is developed to incorporate the data-driven approach into a finite element calculation. This developed data-driven constitutive model is applied to learn and predict the mechanical response of Ti-6Al-4V titanium alloy under multiple loading conditions, including five different loading rates, four different temperatures, and thirteen different stress states. The excellent correlation with the experimental results demonstrates the high accuracy and generality of the presented approach, especially its capability for predicting unknown nonlinear stress–strain response. The presented theory reveals the great potential of employing such a data-driven approach in computational mechanics.

Strain rate response and rheological characteristics of ZrCuNiAl bulk metallic glass in supercooled liquid region

In this study, the plastic deformation behavior of Zr55.7Cu22.4Ni7.2Al14.7 bulk metallic glass (BMG) in the supercooled liquid region (SLR) was studied by high temperature compression experiments at various strain rates. The results show that the high temperature plastic deformation behavior of the BMG in SLR is highly sensitive to the strain rate. With the decrease in strain rate, the steady-state flow stress and peak stress decreases, and the viscosity increases. Meanwhile the stress overshoot gradually disappears, the deformation of the BMG specimen changes from non-Newtonian flow to near-Newtonian flow, and there is a critical strain rate of 5 × 10−4 s−1. The surface deformation profile changes from an "S" shaped truncated cone to a true truncated cone. The plastic deformation of BMGs at room temperature is completed by the initiation and expansion of the shear bands, while the high temperature plastic deformation is caused by the generation and annihilation of free volume.

Revisiting the effect of sabot on the incident signals of split-Hopkinson pressure bar

In typical split-Hopkinson pressure bar set-ups, the striker bar is propelled in a barrel of larger diameter. Teflon/brass sabots are used to concentrically-align the striker inside the barrel. The influence of the area mismatch between barrel and striker, length of the sabots and interface condition between sabot and striker are analyzed in detail using finite element simulations. We show that for a given geometry of the sabot, a frictionless interface does not alter the incident signals. In the presence of friction, the incident signals deviate from the classical trapezoidal shape. The magnitude of the deviation depends on the geometry of the sabot. As an alternative to the shrink/press fitted sabot, a stepped striker is used to eliminate some issues faced during the usage of the shrink/press-fitted sabot. The stepped striker has a non-uniform diameter such that at two locations its diameter is that of the barrel, and at other locations it has the same diameter as the incident bar. The influence of the geometry of the stepped striker on the distortion of the incident signal is investigated in detail using the method of characteristics. A parametric study is used to quantify this distortion for various geometric configurations of the stepped striker. Three striker geometries are chosen from these configurations to validate the parametric study using experiments. High strain rate characterization of SS304 is also carried using these strikers to illustrate the effect of the geometry of the stepped striker on the stress versus strain and strain rate versus strain response.

Brain strain rate response: Addressing computational ambiguity and experimental data for model validation

Traumatic brain injury (TBI) is an alarming global public health issue with high morbidity and mortality rates. Although the causal link between external insults and consequent brain injury remains largely elusive, both strain and strain rate are generally recognized as crucial factors for TBI onsets. With respect to the flourishment of strain-based investigation, ambiguity and inconsistency are noted in the scheme for strain rate calculation within the TBI research community. Furthermore, there is no experimental data that can be used to validate the strain rate responses of finite element (FE) models of the human brain. The current work presented a theoretical clarification of two commonly used strain rate computational schemes: the strain rate was either calculated as the time derivative of strain or derived from the rate of deformation tensor. To further substantiate the theoretical disparity, these two schemes were respectively implemented to estimate the strain rate responses from a previous-published cadaveric experiment and an FE head model secondary to a concussive impact. The results clearly showed scheme-dependent responses, both in the experimentally determined principal strain rate and model-derived principal and tract-oriented strain rates. The results highlight that cross-scheme comparison of strain rate responses is inappropriate, and the utilized strain rate computational scheme needs to be reported in future studies. The newly calculated experimental strain rate curves in the supplementary material can be used for strain rate validation of FE head models. Statement of significance–Delineates a theoretical clarification of two algorithms for strain rate computation.–Highlights the strain rate responses directly depends on the computational schemes.–Presents experimental strain rate curves, serving as references for strain rate validation of finite element head models.

Strain Rate Effect on the Thermomechanical Behavior of NiTi Shape Memory Alloys: A Literature Review

A review of experiments and models for the strain rate effect of NiTi Shape Memory Alloys (SMAs) is presented in this paper. Experimental observations on the rate-dependent properties, such as stress responses, temperature evolutions, and phase nucleation and propagation, under uniaxial loads are classified and summarized based on the strain rate values. The strain rates are divided into five ranges and in each range the deformation mechanism is unique. For comparison, results under other loading modes are also reviewed; however, these are shorter in length due to a limited number of experiments. A brief discussion on the influences of the microstructure on the strain-rate responses is followed. Modeling the rate-dependent behaviors of NiTi SMAs focuses on incorporating the physical origins in the constitutive relationship. Thermal source models are the key rate-dependent constitutive models under quasi-static loading to account for the self-heating mechanism. Thermal kinetic models, evolving from thermal source models, address the kinetic relationship in dynamic deformation.

Strain rate response of mechanical behaviors for Fe-8Mn-6Al-0.4C duplex low-density steels with different austenite stabilities

Duplex low-density steels exhibit excellent mechanical properties under quasi-static tensile tests with the help of the transformation-induced plastic (TRIP) effect produced by the deformation-induced martensitic transformation (DIMT), which is sensitive to the strain rate. Therefore, adjusting the microstructure to accommodate the deformation at different strain rates is crucial for the optimal design of high-performance duplex low-density steels. In this study, Fe-8Mn-6Al-0.4C low-density steel was subjected to intercritical annealing (IA) treatment to obtain duplex microstructures with an inhomogeneous distribution of austenite grain sizes and tensile tests were performed at two strain rates. The response of the mechanical behavior to the strain rate was investigated, and the mechanical stability of austenite was evaluated using a method based on the grain size. The results show that the diverse mechanical behaviors of experimental steel depend mainly on the mechanical stability of austenite rather than the stacking fault energy (SFE). The mechanical stability of austenite increased with decreasing annealing temperature and was further enhanced by adiabatic heating at a higher strain rate. Accordingly, the DIMT mode changed from a stress-induced transformation to a strain-induced transformation until the DIMT was inhibited by adiabatic heating. The improvement in the mechanical properties of the experimental steel is attributed to the sustainable DIMT with a reasonable mechanical stability of austenite.

Influence of Strain History on Dynamic Strain Localization and Stress State During High-Rate Tensile Loading of Titanium Alloys: Experiments, Modeling, and Analytical Methods

Abstract The determination of the mechanical response of engineering materials subjected to high loading rates plays an important role in determining their performance and application. The high strain-rate tensile response of metals is usually investigated by means of the split-Hopkinson tension bar (SHTB) apparatus. The interpretation of the obtained results is, however, subjected to analogous stress and strain uniformity challenges present during quasi-static tensile experiments. Beyond the onset of necking, strains cease to be uniform along the gauge length and localize around the necking zone. Consequently, the nominal strain rate underestimates the effective strain rate experienced by the material. The analysis of the effective strain rate and stress state beyond the onset of necking has received considerable attention in the literature. Several research efforts have focused on the optimization of the geometry of specimens to be employed for the characterization of the dynamic tensile response using the SHTB. The present work investigates, systematically, the effects of strain history and adiabatic heating on the stress state during dynamic loading. A series of monotonic and various strain history experiments were conducted and analyzed. The diameter evolution, effective strain rate, and temperature histories were measured for all conducted experiments. Numerical simulations were carried out to examine the stress state during strain localization and to accurately reproduce engineering and local thermos-mechanical variables. The effectiveness of existing postnecking corrections for high-rate experiments is assessed. A modified postnecking correlation taking into account the effects of adiabatically induced thermal softening is proposed.

Micromechanical response of pure magnesium at different strain rate and temperature conditions: twin to slip and slip to twin transitions

The strain rate (ε˙) and temperature (T) dependent mechanical response of single crystal magnesium (Mg) micropillars compressed along the [2¯110] direction (a-axis) is investigated from room temperature to 573 K and from 10-3 to 100 s-1. The loading direction was chosen to disfavour basal slip activation by a low Schmid factor, allowing the investigation of the rate-sensitivities of extension twinning and prismatic slip. For T ≤ 423 K, the plasticity was governed by extension twinning for the entire range of the applied strain rates. At T > 423 K and for ε˙ ≤ 10 s-1, extension twinning did not occur and a continuous plastic flow induced by prismatic dislocation mediated plasticity was observed: the twin to slip transition takes place due to the decrease of the critical resolved shear stress of non-basal slip. For ε˙ > 10 s-1, however, the accommodation of the plastic deformation by activation of prismatic slip is not enough to match the applied deformation rate, favouring again deformation twinning. The first part of this work provides a complete overview of the mutual effects of T and ε˙ on the transition points of deformation modes in Mg at the microscale. In a second stage, the influence of thermal and kinetic contributions on the evolution of the flow stress leading to the slip to twin transition at 573 K has been assessed in more detail. Within the slip-dominated plasticity regime, this work provides a quantitative assessment of the increases in the saturation stress (stage III) with ε˙ at high temperature, showing how the strain rate dependency of the dislocation generation rate in the pillar and escape rate at the free surfaces of the structure controls the stress evolution in Mg microcrystals.

High temperature and strain-rate response of AA2124-SiC metal matrix composites

This paper presents the results of the study of the dynamic impact behaviour of the AA2124-SiC Metal Matrix Composite (MMC) material with different particle reinforcement sizes and qualities using a compressive Split-Hopkinson Pressure Bar (SHPB) apparatus. Mechanical tests were performed at strain rates 1000 s−1, 2000 s−1, and 3000 s−1 and at temperatures of room temperature (25 °C), 100 °C and 200 °C. Microstructural analyses were carried out on the samples pre and post-compression experiments to study the fracture characteristics and mechanisms of the MMC materials. The flow stress-strain, strain rate, temperature effects and deformation mechanism were investigated. The backscattered electron images show that a higher strain rate of deformation induces the formation of denser and smaller grain size of CuAl2 precipitates, especially in composites with smaller SiC particle sizes. Temperature has posed a minor effect on the microstructural change. Heating the samples close to a solution treatment temperature, and then followed by an air quenching has resulted in a fine dispersion of CuAl2 precipitates, as well as a high saturation for the materials with a higher volumetric fraction of SiC reinforcement. The SHPB compression results reveal that the 225XF material has developed the highest stress among all materials. For materials with a higher volumetric fraction of SiC reinforcement (225XE and 225XF), cracks and failures have appeared in the samples during high strain rate and high-temperature compression experiments, which is believed to be caused by the increased brittleness of the material as a result of intensified oxide phases.

Numerical modeling of the effect of nozzle diameter and heat flux on the polymer flow in fused filament fabrication

A numerical model that fully account for the velocity of the traveling filament (push velocity) in the liquefier is presented in the current work to predict the pressure, temperature, outlet melt viscosity, strain rate, and velocity in the hot-end of a FFF system for printing tough-poly(lactic acid) (TPLA). The numerical model was thoroughly validated by comparing the model predictions with experimentally measured feeding force data. The predicted numerical results closely approximated the experimentally measured feeding force. Then the model was also validated with extrudate temperature, measured with a thermal imaging camera, and the results obtained are in good agreement. Outlet capillary diameter, feeding rate, and heat flux (quantified in terms of Nusselt number) were varied to determine the response of pressure field, temperature, velocity, viscosity, and strain rate in the liquefier. The results show that an increase in the nozzle outlet diameter decreases the extrusion pressure in the hot-end. The maximum pressure predicted for TPLA is 3.34, 2.91, and 2.04 MPa for the 0.4, 0.6, and 0.8 mm outlet diameters nozzles, respectively. Also, an increase in the nozzle outlet diameter decreases the central velocity at the outlet and decreases the shear rate with an increase in the viscosity of TPLA at the exit during material extrusion. The area-weighted averaged outlet temperature for TPLA decreases as the feeding rate increases for all three nozzle diameters. Elucidated from the simulation results, significant variation of the normalized velocity at the center of the nozzle outlet suggests that different printing speeds for TPLA material extrusion should be set for different nozzle diameters. Otherwise, the accuracy and precision of the gantry motion during layer deposition on the print will be compromised. The simulation results indicate that based on the 90% core melting temperature requirement, at a liquefier set temperature of 503 K, the TPLA should be printed below 80mm/min for all outlet diameters considered. A Nusselt number of 49.61 was observed to be the upper limit where an increase in the heat flux in the liquefier has no significant effect on the area-weighted averaged outlet temperature of TPLA.

High strain rate and high temperature mechanical response of additively manufactured alloy 625

Alloy 625 is an important alloy in many industries, including aerospace, providing good mechanical properties in high temperature and corrosive environments. It also retains good properties when additively manufactured using Laser Powder Bed Fusion (LPBF). The LPBF process introduces complex heating and cooling cycles in the material used, thereby affecting the mechanical properties. As a result, existing constitutive models for alloy 625, are not applicable for the LPBF-fabricated material. Therefore, this study sought to establish appropriate constitutive models to simulate the mechanical response of LPBF-fabricated alloy 625 in the desired range of conditions for aerospace applications: high strain rates and temperatures. This was completed by compressing the samples at two strain rates, 700 s−1 and 1700 s−1, and temperatures ranging from 298 K to 773 K using a Split Hopkinson Pressure Bar (SHPB). The information gained from the models was reinforced with micrographs and electron backscatter diffraction (EBSD) images to examine the microstructure of alloy 625 after LPBF. The results from the SHPB testing were then used to calculate the coefficients for five constitutive models, the Johnson-Cook model, a modified Johnson-Cook model, the Hensel-Spittel model, a modified Hensel-Spittel model, and a modified Zerilli-Armstrong model. The Average Absolute Relative Error (AARE) of these models was calculated, and it was determined that the modified Zerilli-Armstrong model had the lowest AARE of the models used, 2.88 % for as-printed alloy 625 and 2.71 % for heat-treated alloy 625.

Effect of 1wt%Zn Addition on Microstructure and Mechanical Properties of Mg-6Er Alloys under High Strain Rates

In this study, we investigated the high strain rate response of Mg-6wt%Er alloys with 1wt%Zn addition by split Hopkinson pressure bar (SHPB) tests in a range of 900–2500 s−1. Their related microstructures were also characterized by optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattering diffraction (EBSD), and transmission electron microscopy (TEM). In particular, the twinning and stacking faults (SFs) in Mg-6Er and Mg-6Er-1Zn alloys are characterized, and the interactions between twin/SFs and dislocations are analyzed in detail. Compared with twins, the dispersed and dense SFs seem to more readily interact with dislocations, resulting in the enhancement of the strength of alloys. Especially at a high strain rate of 1450 s−1, dislocations are prone to tangle around the twins and SFs, forming low-angle grain boundaries (LAGBs). The addition of Zn in Mg-6Er can make LAGBs more easily transform into high-angle grain boundaries (HAGBs) due to the existence of SFs.

Experimental Investigation of Low-Frequency Distributed Acoustic Strain-Rate Responses to Propagating Fractures

Summary Low-frequency distributed acoustic sensing (LF-DAS) responds to strain changes due to far-field fracture propagation. To better understand the LF-DAS response to fracture propagation, we performed laboratory-scale hydraulic fracture experiments with embedded optical strain sensors. The objectives of this research are to generate hydraulic fractures of known geometry, measure the strain response along the embedded fiber-optic cable comparable to LF-DAS measurements, and use the results to inform the interpretation of field-derived LF-DAS data. The experiments were conducted in unconfined transparent cubic blocks with a dimension of 8 in. on each side. The block was made of transparent epoxy to visualize the fracture propagation. Fiber-optic sensing cables were embedded in the block at different distances to the source of injection. We injected dyed water through an injection tubing to generate a transverse, radial fracture along an initial flaw. An optical interrogator recorded the response of offset fiber Bragg grating (FBG) strain sensors normal to the plane of the fracture. The strain data were visualized on a waterfall plot, akin to visualizations of field-derived LF-DAS data. Dimensional analysis was used to scale the laboratory results to field conditions. We compared the evolution of the strain response at the fiber-optic cable, injection pressure, and rate with known fracture geometry. The measured strains were compared with Sneddon’s (1946) linear elastic solution for a penny-shaped crack and found to follow this behavior. The generated radial fractures in transparent media can be modeled with Sneddon’s linear elastic radial fracture model and a Mode I critical stress intensity factor. The LF-DAS characteristic response of a narrowing region of extension surrounded by compression was exhibited as a fracture that approached and intersected the fiber-optic cable. The experimentally derived strain and strain-rate waterfall plots with known fracture geometry, injection rate, and pressure response provide insight in understanding LF-DAS responses in the field. Furthermore, we developed a method to estimate fracture geometry evolution from the fiber-optic strain data and validated the method against the experimental data.

Plasticity and fracture of AA7075 at elevated strain rates and temperatures

The accurate description of the strain rate and temperature dependent response of Aluminium alloys is a perpetual quest in the hot forming industry. In the present study, uniaxial tension, and notched tension experiments are conducted for an aluminium AA7075-T6 sheet metal at various temperatures and strain rates. The experimental campaign covers strain rates ranging from 0.001/s to 100/s, and temperatures ranging from 20°C to 360°C. We observe low strain rate sensitivity at room temperature, with an increase in strain rate sensitivity as temperature is increased up to 360°C. An YLD2000-3D model is employed to describe the anisotropy of the material. A machine learning based hardening model is employed to capture the complex strain rate and temperature effect on the observed hardening response. Counter-example regularization is utilized to guarantee a convergence in the numeric return-mapping algorithm. Comparing the experimental force-displacement curves with the numerical predictions, the neural network model accurately describes the large deformation response of the material in the post-necking range.

Effect of pore density on the compressive response of open-cell Al foams

The effects of pore density and matrix on the quasi-static and dynamic compressive behaviours of the high porosity open-cell aluminium foams were examined. The results show that pore density has little effect on the collapse strength of the samples under quasi-static conditions. However, as the strain rate increases, the collapse strength decreases with increasing pore density. The different matrix material also shows distinct strain rate response characteristics, which is related to their respective microstructures. The strain-rate sensitivity is mainly attributed to the micro-inertia effect caused by the larger aspect ratio of the cell edges, which was verified by the more transverse elongation of the dynamic compression samples. Moreover, the energy absorption capacity is also discussed in the present paper.