Architected materials based on triply periodic minimal surfaces (TPMS), such as Gyroid structures, are promising candidates for energy absorption applications in aerospace, defense, and biomedical fields due to their tailorable mechanical properties and lightweight design. However, their deformation and failure mechanisms under high-strain-rate loading remain poorly characterized, particularly regarding the influence of manufacturing defects and strain-rate sensitivity on damage localization.This study investigates the deformation and failure mechanisms of selective laser melting (SLM) IN718 Gyroid structures subjected to quasi-static (ɛ̇=0.008s−1) and high-strain-rate (ɛ̇=400s−1 and ɛ̇=550s−1) compressive loading. The methodology integrates hydraulic press and Split Hopkinson Pressure Bar (SHPB) tests analyzed through Digital Image Correlation (DIC) with Finite Element simulations, using an elasto-plastic Johnson–Cook constitutive model to establish an ideal performance baseline.Five distinct mechanical regimes are identified, correlating the stress–strain response with the physical evolution of the structure. Quantitative results show that dynamic loading increases the post-peak force drop from 27.1% to 33.6%, highlighting an earlier onset of damage driven by inertia effects. Furthermore, the numerical–experimental comparison reveals an energy absorption deficit of approximately 17% for dynamic tests, illustrating the performance gap between idealized topologies and their corresponding SLM-manufactured specimens. These insights establish a framework for optimization strategies to enhance dynamic energy dissipation.

This study focuses on the force-time response of cylindrical water ice specimens subjected to impact loadings. Spherical specimens are traditionally used to characterize the impact behavior of water ice. However, they cannot be used to study the geometric effects induced by a cylindrical shape. Impact tests were carried out on a Hopkinson bar at 30 m s-1. These tests have demonstrated the importance of the impact angle in terms of both the increase in the load and the peak force at impact. Contrarily to what was observed for tensile spalling test, porosity has no noticeable impact on the maximum peak force measured here. The importance of the impact angle is illustrated by comparing the mechanical response of ice spheres with pellet cylinders for equivalent kinetic energies and temperatures.

Shear fracture mechanisms (in mode II) are usually observed in plain-concrete structures when subjected to impact loading of a rigid projectile. In the present work, an experimental method is proposed to characterise the confined dynamic shear strength and softening behaviour of concrete. A cylindrical specimen in which to circular notches are preformed is subjected to a dynamic loading through a Split Hopkinson Pressure Bar (SHPB) device. A cylindrical Hopkinson bar is used as input bar whereas a tube is used as output bar. The particle velocities measured by laser interferometers on both input and output bars allow the deduction of the shear stress in the ligament (fractured zone) and the axial displacement in the central zone beside the peripheral zones. Moreover an instrumented confining ring is used to induce a confining pressure on the fractured zone. This experimental method has been employed to characterize the dynamic shear strength of a common concrete at strain-rates as high as 100/s.

In the present study, microconcrete (MC) samples were exposed to dynamic quasi-oedometric compression (QOC) tests and visualised in-situ by the means of MHz synchrotron X-ray phase-contrast imaging in the ESRF synchrotron in order to analyse the damage mechanisms governing the mechanical behaviour of concrete under high-strain-rate confined compression. To do so, small cylindrical samples were placed in polymeric confinement cell and dynamically compressed along their axial direction using SHPB (Split-Hopkinson Pressure Bar) set-up available in ID19 beamline in the European Synchrotron Radiation Facility (ESRF). The damage process was visualized with MHz X-ray phase-contrast imaging along with an ultra-high-speed camera operating at a recording frequency approximately 1 Mfps (million frames per second i.e., 880 ns interframe time). The axial stress and strain temporal profiles were obtained from standard Kolsky's (SHPB) data processing. In addition, data of radial stress and strain within the sample were deduced from non-linear analysis of the mechanical behaviour of the polycarbonate confining cell instrumented with a strain gauge. Finally, the onset and growth of microcracking observed from the equatorial zone of large spherical pores is correlated with deviatoric and pressure measurements showing how the pore collapse process develops during the applied mechanical loading.

Severe damage modes are observed in concrete structures when subjected to impulse loading as projectile-impact or blast loading. For instance, the impact of a kinetic penetrator generates scabbing on the front face, radial cracking in the whole target and, for high impact velocities or a thin target, spalling on the rear face. These damage mechanisms may strongly decrease the penetration resistance of concrete structures. On the other hand, high confining pressures in front of the projectile may lead to a micro-cracking and collapse of pores in the vicinity of the tunnel. Moreover both confined and tensile behaviours are influenced by humidity level of the concrete. Therefore the numerical modelling of concrete slabs under projectile-impact relies on the use of coupled modelling in which the hydrostatic and deviatoric behaviours of the concrete under high pressure is modelled in addition to the anisotropic damage induced in dynamic tensile loading. In the present work, a series of numerical simulations of impact tests have been conducted considering different humidity levels and target thicknesses. The confined behaviour of the concrete material is modelled through the KST (Krieg-Sweenson-Taylor) plasticity model. The so-called DFH (Denoual-Forquin-Hild) damage model combined with a cohesion model is used to describe the tensile strength and softening behaviour of concrete in tension. A series of computations have been performed to assess the influence of the confined behaviour and tensile strength on the ballistic performance of concrete slabs.

Concrete is widely utilized in the construction of critical structures such as nuclear plants, explosive material storage bunkers, and water-retaining facilities. These concrete constructions must be designed to withstand potential threats from terrorist attacks or accidental events, such as projectile impacts. When a slab undergoes severe impact loading, the concrete material experiences high loading rates and encounters a complex stress state, characterized by high confined compression stress near the point of projectile impact and tensile stresses near the slab’s free edges. This can result in potential spalling and scabbing on the front and rear faces of the slab. Addressing this issue, the discrete element method (DEM) proves particularly effective due to its capability to handle discontinuities with ease. To this end, a DEM model was implemented in the industrial computer program Europlexus, a finite element code for analyzing fluid–structure systems under transient dynamic loading. In the previous studies, the authors introduced a compaction model accounting for pore closure and free water presence in concrete, validated through simulations of penetration tests on thick concrete targets with passive confinement. This paper shifts focus to the DEM simulation of edge-on impact tests conducted on non-confined concrete tiles using ogive-nose projectiles. Unlike the aforementioned penetration tests, these original experiments involve moderate mean stress, highlighting the influence of tensile stresses on the fracturing process. The results validate the model’s ability to accurately represent fracturing and cratering processes in concrete, which are highly dependent on loading rates.

Understanding ice flexural behavior is essential for assessing interactions with structures in cold environments. The mechanical response of ice depends on microstructural properties, such as grain size and porosity, which vary widely in natural ice. Existing bending test data often lack detailed microstructural characterization, making it difficult to interpret or generalize the results. In brittle materials such as concrete or rock, pores commonly act as failure-initiating defects. Therefore, porosity (pore size, shape and density) should be considered a key parameter when studying ice fracture. Here, we provide a robust set of bending experiments on well-controlled isotropic polycrystalline ice microstructures and investigate the role of porosity in ice failure. Two porosity levels were studied, characterized at high resolution by micro-computed X-ray tomography. Analyzing the bending failure by means of the Weibull model reveals that the sample failure is initiated by different defect populations, in relation to the porosity. Providing that the Griffith/Irwin failure criterion can be applied, the measured pore distribution allows the prediction of a critical stress for defect activation. Compared with measured failure stress, this prediction enables discriminating the defect population responsible for failure and offers a mechanistic interpretation of the volume effect observed in porous ice flexural strength.

Ceramic materials are widely used in armor or protective structures, providing weight saving at equivalent performance in comparison to their steel counterparts. Plate-impact experiments are commonly used to investigate the dynamic behavior of ceramics under compressive loading. Using the particle velocity measured at the back of the target, some mechanical properties such as the Hugoniot elastic limit (HEL) as well as the Hugoniot curve of the material can be deduced. Nevertheless, these tests do not provide a direct measurement of the plastic hardening (post-HEL) behavior of the target. In the present work, an experimental shockless plate-impact configuration was developed and implemented to conduct a Lagrangian analysis. This configuration relies on the use of a wavy-machined flyer plate impacting a target made of a buffer, two ceramic plates of different thicknesses, and two window plates as backing. First, the use of wavy flyer plates to generate a loading ramp was validated by considering the impact of the wavy-machined flyer plate against a target, both made of 316L steel. A numerical analysis of this test was developed to confirm the pulse-shaping effect observed experimentally. Next, a ceramic, F99.7 alumina was subjected to the shockless plate impact test in Lagrangian configuration considering the same steel as a buffer and flyer plate material. These tests coupled with Lagrangian analysis enable the curve of axial-stress vs axial-strain beyond the isentropic elastic limit (IEL) to be deduced. The experimental data allow identifying the parameters of an elastoplastic with strain-hardening model to describe the behavior of the tested alumina.

Although the dynamic behavior of ceramics is less well-known than that of other material families such as metals, polymers, composites, or even geomaterials, these materials are nonetheless widely used in many fields under dynamic or shock loading. Under such extreme conditions, these materials exhibit damage and deformation modes that are difficult to observe under static loading. For this reason, the study of their behavior under high strain rate is a major challenge. These materials combine low density compared with dense materials such as steels with interesting, and even exceptional properties under compressive loadings over a wide temperature range, making them particularly valuable as part of shielding solutions against high-speed impact or high-energy-density pulse loading. On the other hand, these materials exhibit low toughness and ductility in the absence of confinement, which explains their ability to fragment under dynamic tensile loading. In addition, the damage and deformation modes in these materials are particularly sensitive to microstructural parameters such as sintering defects, flaws, grain boundaries, and secondary phases. The experimental study of the dynamic behavior of these materials requires the use of specific experimental methods to characterize their strength under high-rate tension, as well as under high confinement pressure in their pristine (unfragmented) or fragmented states. On the other hand, plasticity and anisotropic damage models must be developed and implemented in numerical codes, considering the influence of loading rate, level of confinement pressure, and deformation or fragmentation state of the ceramic material. This chapter provides a nonexhaustive summary of the work available in the literature on these topics.

Properties of concrete can be tailored by selecting its constituents, composition, production, and curing procedure. A historical overview of the development of high-strength fibre-reinforced concrete (HSFRC) is given. The role and contribution of the main constituents to the mechanical properties are described to illustrate the possibilities of controlling the concrete properties. Next, the strength and deformation capacity under static loading as a function of matrix and fibre properties is summarized. The principles of the dynamic response mechanisms, as described in Chapter 7 for ordinary concrete, are applied to HSFRC to predict the tendencies in rate effects. These are compared with test data on strength and deformation capacity given in the literature as well as the semiempirical equations for the dynamic increase factor on strength. The combination of data and knowledge on the dynamic response mechanisms reveals the main characteristics of HSFRC for tensile loading in dynamics. The dominant effect of fibre orientation on the postpeak response and the impact resistance of HSFRC is illustrated with a dedicated impact test, showing the damage development in time.

Modified static and dynamic shear tests are introduced to study the shear behavior of concrete-rock interfaces under static and dynamic loading in the context of low confinement stresses. Static and dynamic shear tests of concrete-sandstone and concrete-granite interfaces are performed using these techniques. Three levels of interface roughness are considered: smooth, bush-hammered, and rough rock surfaces. The results of these tests show that in both static and dynamic regimes, the shear evolution of concrete-rock interfaces can be described according to three successive stages: the shear stress accumulation, the shear slip, and the residual shear stress stage. The main parameters driving the shear process are the concrete-rock bonds, the interface roughness, and the residual friction. However, unlike in the static shear evolution, in the dynamic shear evolution, the concrete-rock bonds and the roughness seem active in the shear stress accumulation stage. Furthermore, the correlation between the shear strength and the normal stress is stronger in static than dynamic conditions. The significance of the normal stress on the dynamic shear strength appears more important in rough concrete-granite interfaces than in the other two interfaces. Lastly, the dynamic peak shear strengths of all the interfaces tested are three to four times higher than their static counterparts.

Background Shear behaviour of concrete under high confining pressure has not been thoroughly studied despite being widely observed in concrete structures subjected to high blast loading or projectile impact. Objective The objective of the present study is to propose an experimental method to investigate the shear behaviour of concrete under high confinement in static conditions. Methods This method is based on the Punch-Through Shear testing technique. A specimen with two cylindrical notches is first subjected to an active confinement pressure by means of a triaxial cell and an axial loading is then applied to punch through the central part of the specimen. However, in the previous PTS experiments, the inner cylindrical parts being subjected to uniaxial compression, the level of confining pressure applied in the first stage was usually limited to the sample uniaxial compression strength. In the present work, much higher compression stresses of a few hundreds of MPa are applied to the specimen in both radial and axial directions thanks to the small metallic rings used to confine the inner cylindrical parts of the specimen . A series of numerical simulation based on finite-element method is conducted in order to optimize the notches and sample dimensions. Results Experimental tests conducted on a common concrete showed that the confinement rings successfully prevented any compression damage in the central part during sample pressuring and shearing. The experiments conducted at different levels of confining pressure showed that the higher the confinement level the higher the concrete shear strength. Experiments done with a confining pressure of 100 MPa with two different ligament lengths showed that higher nominal shear stress is obtained with a smaller shear surface. Conclusion The proposed experimental technique allows reaching confining pressure up to 150 MPa (which corresponds to radial stress of 374 MPa in the ligament) and nominal shear strain of about 38% in the ligament of the concrete sample and confirms that the shear strength increases with the level of normal stress applied to the sheared surface.

The present paper describes a novel experimental method for characterising the confined shear strength of concrete or rock‐like materials based on the use of pre‐stressed sample. This method, called PS‐PTS (Pre‐Stressed Punch‐Through‐Shear), employs a metallic confinement cell that is first quasi‐statically deformed so the concrete sample can be introduced in between the cell jaws. The confinement force is transmitted to the sample in the unloading stage. It is shown that this initial pre‐load level can be predicted by an elastic closed‐form solution. Strain‐gauges glued on the cell allow the confinement level applied to the sample to be experimentally measured during the pre‐stressing stage and the shear stage. In the next stage, the central part of the sample is subjected to a differential displacement towards the lateral parts by means of a hydraulic press so the confined shear strength of the tested material can be deduced. The results are compared to the data previously obtained with an “oedometric” confinement cell in terms of confinement stresses and shear strength.