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The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

The mechanical properties of polymers, particularly as a function of temperature and strain rate, are key for implementation of these materials in design. In this paper, the compressive response of low density polyethylene (LDPE) was investigated across a range of strain rates and temperatures. The mechanical response was found to be temperature and strain rate dependent, showing an increase in stress with increasing strain rate or decreasing temperature. A single linear dependence was observed for flow stress on temperature and log strain rate over the full range of conditions investigated. The temperature and strain rate data were mapped using the method developed by Siviour et al. based on time–temperature superposition using a single mapping parameter indicating that there are no phase transitions over the rates and temperatures investigated. Taylor impact experiments were conducted showing a double deformation zone and yield strength measurements in agreement with compression experiments.

This study investigates the dynamic response characteristics of aluminum foam materials under low to medium-high velocity impact loading, elucidating their deformation mechanisms and energy absorption capabilities through an integrated experimental and numerical simulation approach. The multi-stage deformation behavior of aluminum foam was investigated through the Taylor impact test, which demonstrated that impact velocity significantly affects its stiffness and energy absorption capability. The accuracy of stress distribution and mechanical properties during the impact process is validated, and the deformation behavior under medium- and high-speed impact conditions is clearly revealed. Through integrated macroscopic and microscopic analyses, the dynamic response characteristics of aluminum foam under various impact loads are systematically investigated, elucidating the mechanisms of internal pore collapse and dynamic compressive behavior, thereby providing robust theoretical support for the optimized design of aluminum foam in cushioning and protective applications.

The mechanical properties of polymers are becoming increasingly important as they are used in structural applications, both on their own and as matrix materials for composites. It has long been known that these mechanical properties are dependent on strain rate, temperature, and pressure. In this paper, the methods for dynamic loading of polymers will be briefly reviewed. The high strain rate mechanical properties of several classes of polymers, i.e. glassy and rubbery amorphous polymers and semi-crystalline polymers will be reviewed. Additionally, time–temperature superposition for rate dependent large strain properties and pressure dependence in polymers will be discussed. Constitutive modeling and shock properties of polymers will not be discussed in this review.

The increasing interest in Additive Manufacturing (AM) technologies is mainly driven by their high design flexibility and on-demand production. As these processes expand, there is a critical need to explore the material properties of resulting products under diverse loading conditions. This work investigates the impact response of the as-built aluminum alloy AlSi10Mg, additively manufactured employing a laser powder bed fusion (L-PBF) process. Taylor-cylinder impact tests have been performed with a light gas gun at different impact velocities to probe material deformation and damage behavior under high-rate loadings and complex stress paths. Three building orientations were systematically investigated– horizontal, vertical, and at 45°. At lower striking velocities (between 180 and 200 m/s), observable mushrooming deformation occurred with no apparent damage. The shape of the impact faces and deformed profiles were recorded to assess deformation differences across the tested printing directions. In the intermediate range of velocities (240–260 m/s), shear cracking emerged as the principal damage mechanism, resulting in the formation of 45°/135° oriented cracks on the samples’ lateral surface. Increasing the impact velocity promoted these cracks’ growth, ultimately leading to the samples’ fragmentation. The vertically printed sample exhibited a slightly lower onset fragmentation velocity than the other two building directions.

This paper presents the estimation of the parameters of the Cowper-Symonds material model of a commercial copper alloy from a single Split Hopkinson Pressure Bar Test using an inverse method. Parameters were identified by minimizing the error between the transmitted strain signal predicted by a finite element model and those observed experimentally. The Taylor Test was used to validate the identified parameters by comparing the experimental final length of impacted specimens and the ones predicted by a finite element model using the identified parameters. Also, identified parameters were contrasted with those found by a traditional curve-fitting approach. It was found that finite element models using the identified parameters are better able to predict plastic deformation than those using parameters from traditional curve-fitting.

During daily functions, our wrist moves through an oblique plane, named the dart-throwing motion (DTM) plane. This plane is considered a more stable plane because the proximal carpal row remains relatively immobile. However, rehabilitation programs that incorporate exercising in the DTM plane have yet to be explored. The purpose of this study was to evaluate the rehabilitation outcomes after treatment in the DTM plane compared with outcomes after treatment in the sagittal plane after distal radius fracture. This is a pilot randomized controlled trial. Subjects after open reduction internal fixation were assigned into a research group (N = 12; ages 48.7 ± 7.3) and a control group (N = 12; ages 50.8 ± 15). The control group activated the wrist in the sagittal plane, whereas the research group activated the wrist in the DTM plane. Range of motion, pain levels, functional hand motor skills tests, and satisfaction from self-training exercise were measured before and after a 12-session intervention. The outcome measures were similar between the treatment groups. The research group reported significantly higher satisfaction rates than the control group on topics such as general satisfaction (research group: 3.4 ± 0.7, control group: 2. 5 ± 1.2, P = .030), motivation to exert oneself (research group: 2.8 ± 1.0, control group: 2.3 ± 1.2, P = .009), progressed function (research group: 3.4 ± 0.7, control group: 2.4 ± 1.1, P = .012), and self-training contribution to the daily function (research group: 3.4 ± 0.7, control group: 2.5 ± 1.2, P = .030). Pilot results do not favor one treatment method over the other. However, exercising in the DTM plane may contribute to the satisfaction of the client and increase self-training motivation. •A software that automatically fits a swan-neck orthosis to a patient is provided.•The weight of the 3D-printed orthosis was significantly smaller than that of the manual orthosis.•Occupational therapy students were more satisfied with the fit, esthetics, overall process and product of the 3D-printed orthosis.•The automated software might be the missing link for integration of 3D printing in the clinics.

AbstractA mathematical model of a solid body with mesoscopic defects is presented and validated. The constitutive relations proposed earlier allow describing the deformation behavior of typical elastic-viscoplastic materials (metals and alloys) in a wide range of strain rates, temperatures, and stresses. Methods for identifying unknown parameters of the model by solving a number of independent optimization problems using data from independent experiments are developed and implemented. For identification we use both the results of a literature review and experimental data. The experimental study on high-speed collision of a cylindrical specimen with an obstacle in the form of a bar (Taylor–Hopkinson test) is carried out by recording the temperature field in the course of deformation. The data are used to verify the model. For comparison the calculations are performed in the three-dimensional statement and in the axisymmetric statement. The formulated boundary value problems are solved numerically by the finite element method. The results of numerical calculations are in good agreement with the experimental data: the shape of the specimen after collision and the measured temperature (mechanical energy dissipation during inelastic deformation) coincide. This confirms the adequacy of the developed mathematical model and indicates that it can be used to solve both fundamental and applied problems of solid mechanics. The analysis of parallelism efficiency shows that the use of eight cores yields a five-fold acceleration and, as the number of cores increases further, this trend presumably continues.

The behavior of three copolymers high density polyethylene at high rate loading was investigated. Namely, one unimodal type (HDPE-1) and two bimodal type. Structure of PE samples was characterized by 13C NMR (Carbon-13 nuclear magnetic resonance). The Taylor impact test was used. Specimens in form of a cylinder (14 mm in diameter and 50 mm in length) were fired against a steel bar. Striking velocities achieved up to 116 m/s. No permanent strain of these specimens was detected. Numerical simulation of these tests showed that the material behavior is probably viscoelastic. Results showed that there was no difference in the impact behavior of tested polymers. This conclusion was obtained both for the results in the time domain and the frequency domain.

Numerical simulation of impact and shock-wave interactions of deformable solids is an urgent problem. The key to the adequacy and accuracy of simulation is the material model that links the yield strength with accumulated plastic strain, strain rate, and temperature. A material model often used in engineering applications is the empirical Johnson–Cook (JC) model. However, an increase in the impact velocity complicates the choice of the model constants to reach agreement between numerical and experimental data. This paper presents a method for the selection of the JC model constants using an optimization algorithm based on the Nesterov gradient-descent method. A solution quality function is proposed to estimate the deviation of calculations from experimental data and to determine the optimum JC model parameters. Numerical calculations of the Taylor rod-on-anvil impact test were performed for cylindrical copper specimens. The numerical simulation performed with the optimized JC model parameters was in good agreement with the experimental data received by the authors of this paper and with the literature data. The accuracy of simulation depends on the experimental data used. For all considered experiments, the calculation accuracy (solution quality) increased by 10%. This method, developed for selecting optimized material model constants, may be useful for other models, regardless of the numerical code used for high-velocity impact simulations.