Fibre-reinforced composites (FRPs) are strong, light and corrosion resistant. From marine to aerospace and space applications, potential benefits from wider use of high-strength FRPs include increased fuel efficiency and service life. However, they are also highly complex, with strongly anisotropic properties which depend not just on their constituents but also their meso- and micro-structural properties like fibre architecture and fibre-matrix bonding. Developing a more robust understanding of how they behave is therefore critical if we hope to use FRPs more. High-strain-rate loading conditions are of particular importance for composites, as their high specific strength makes them ideal for many applications involving rapid accelerations, which are often at risk of high-speed impact threats. Here, FRPs with similar fibre and matrix components, but differing fibre architectures, have been studied at loading rates of the order of 0.01/s and 1000/s under both ‘pristine’ condition and after ageing by full saturation in a demineralised water bath at 40 °C. Experiments were designed to ensure equilibrium is reached early in the deformation process to discern information about stiffness and toughness, and the use of energy flux is considered in terms of power and total work done to characterise both experimental conditions and material response.

This review aims to assess publications relevant to understanding the rate-dependent dynamic behaviour of glass- and carbon-fibre reinforced polymer composites (FRPs). FRPs are complex structures composed of fibres embedded in a polymer matrix, making them highly anisotropic. Their properties depend on their constituent materials as well as micro-, meso- and macro-scale structure. Deformation proceeds via a variety of damage mechanisms which degrade them, and failure can occur by one or more different processes. The damage and failure mechanisms may exhibit complex and unpredictable rate-dependence, with certain phenomena only observable under specific loading conditions or geometries. This review focusses on experimental methods for measuring the rate-dependent deformation of fibre composites: it considers high-stain-rate testing of both specimens of ‘simple’ geometry as well as more complex loadings such as joints, ballistic impact and underwater blast. The effects of strain rate on damage and energy-based processes are also considered, and several scenarios identified where strength and toughness may substantially decrease with an increase in strain rate.

The transport of energetic materials—whether by truck over rough terrain, or attached to the undercarriage of a high-performance jet aircraft—carries a certain level of inherent risk as the repeatedly applied stresses from vibration may lead to heating, mechanical degradation, and potentially even the triggering of an ignition event. Increasing knowledge of the underlying physics which control ignition is allowing us to better understand, and thus reduce, the risk of a catastrophic event occurring. The Apollo and Space Shuttle programmes provided motivation for research into the topic in the 1960s and 1970s, and some recent studies have focussed on the grain-scale physics of ignition. However, much of the useful insight has arisen from work with other primary applications in mind. Therefore, this review aims to bring together literature from several fields, with the intention of better understanding vibration-induced heating (VIH) phenomena in energetic materials. Sensitivity, VIH in viscoelastic polymers and inert composites, and a technique known as vibrothermography which uses VIH to detect cracks, are all considered where relevant read-across can be found. Often being viscoelastic materials and composites with complex rheology, energetic materials subjected to vibrational loading tend to warm up, with potential for even greater temperature rises due to anisotropy-driven localised heating mechanisms. Binders soften as temperature rises, and the chance of damage increases, which may lead to runaway heating and thermal failure (if mechanical failure does not occur first).

We review recent experimental efforts at the Cavendish Laboratory regarding the dynamic response of silica sand under a variety of loading rates and geometries - principally plate impact and ballistic penetration. By studying the response of several similar sands in multiple loading scenarios, significant insight has been gained into the key phenomena controlling response. While dynamic behavior is largely controlled by grain-grain contact phenomena, there is a shift from shear behavior and lubrication dominating low rates (where long-range force chains dominate), to compression and stress focusing at high rates - with the transition occurring around the sound speed of the granular material in question.

The dynamic response of sand is of interest for a wide range of applications, from civil engineering to asteroid impact, in addition to defense and industrial processes. Granular dynamics are controlled by a complex network of intergrain force chains; yet, our understanding of how grain morphology, moisture, rate, and loading geometry affect the response to rapid compaction remains limited. Here, we show how just 1% moisture can significantly reduce penetration resistance in silica sand, while smoother-grained material-with a similar bulk density, grain size, and mineralogy-exhibits markedly improved stopping power. Cylindrical targets are impacted by spherical steel projectiles, with Digital Speckle Radiography employed to determine both the penetration depth and the sand bed displacement at a series of incremental time steps after impact. The results provide substantial insight into how slight adjustments to grain-grain contact points can affect the bulk dynamic response of brittle granular materials.

A large number of experiments have been conducted using the Cavendish single stage gas gun to investigate the dynamic properties of sand. The results included successful measurements of release in dry materials, demonstrating that this is markedly different to the loading path. The effect of moisture was examined and shown to be strongest where the material was close to saturation, at which point the microstructure of the exact sample configuration plays a significant role in the response. Finally, the effect of sample morphology was probed, and whilst it was found to be significant at low rates, in the shock regime impedance appears to be more strongly influenced by the presence of moisture or a fraction of small particle size debris.

The processes occurring during shock compaction and release of granular materials are complex, and the changes resulting from addition of moisture are not well understood. Here, the results from a series of plate impact experiments are reported, detailing the shock response, and release to vacuum, of a quartz sand. To measure the effect of adding moisture, the sand was tested under dry, partially and fully saturated conditions. The results show that addition of a small quantity of water has little effect on the shock or release properties, while fully saturated samples display a markedly different response. Furthermore, the data suggest that the shock response of fully-saturated material may vary between samples with very similar bulk properties. A microstructure-based mechanism for how this may occur is suggested.

Rhodamines are analyzed to judge their suitability in dye sensitized solar cells, revealing their predominant auxiliary role with DSC-functional co-sensitizers.

There is considerable interest in the high-rate compaction of brittle granular materials such as sand. However, the vast majority of studies focus on a single granular system, limiting our ability to make comparisons between materials to discern how granular structure manifests as bulk material response. Here, three different silica sands with similar grain size and shape are studied: we compare a rough quarry sand, a smoother-grained sand, and a sandy loam. Quasi-static compaction and planar shock loading responses are compared, and recovered samples analyzed. The combination provides information regarding the interplay between granular properties, loading conditions, and material response. We show that the fundamental grain-scale behaviour depends on loading conditions: At low strain rates compaction behaviour is dominated by grain morphology, and in particular, smoothness and particle size distribution. Under shock loading, grain rearrangement and force chain effects are suppressed, and the nature of inter-granular contact points, modified by the presence of moisture or fines, is most important. Furthermore, grain fracture under shock loading is substantially reduced with increasing moisture content.

Relatively little is known about the changes that occur in the shock compaction and release of granular matter with varying levels of moisture. Here, we report a series of plate impact experiments giving shock Hugoniot and release data for a well characterized sand at dry, 10% moist, and saturated water contents. The results reveal that at low moisture content the shock impedance is slightly reduced, while the release remains predominantly inelastic. Close to saturation, much more substantial changes occur: the shock impedance stiffens substantially, the Hugoniot appears to split into two branches, and the release becomes almost completely elastic. We discuss mechanisms underpinning these changes in behavior.

A considerable body of knowledge exists on the shock properties of dry sand. However, capturing the release properties has proven experimentally complex, and currently little information exists on the topic. The measured Hugoniot and release behaviour from a number of experiments is presented, carried out with the aim of furthering understanding of the fundamental physics behind the unloading of dry sand from a shocked state.

The dynamic response of granular materials to an applied shockwave is of wide ranging importance. While the shock Hugoniot has been studied, the shock-release of granular systems has never been experimentally characterised. Here, we present a simple approach to such measurements and present a series of plate impact experiments providing release data for a well characterised dry sand. We discuss the origin of the release behaviour, which we support with further measurements on a weakly bound sandstone.

Case studies are examined for several new high-rise residential and hotel buildings proposed for construction over or near underground and surface transit systems. Baseline vibration measurements were taken on grade and existing building structures and projected against standard functional vibration criteria (ANSI S3.29 / ISO 2631 2). Through post-construction testing and client feedback, the vibration and structure-borne noise impacts were field verified. Study results offer insight into the correlation between these vibration criteria and the subjective human perceptions of various sensitivities. Further items of discussion include the relative effects of various architectural constructions, building types, and applications as well as mitigating sound and vibration controls.