This study revealed that the mass ratio of large anisometric particles (platelets) to ultrafine, equiaxed particles strongly influences dynamic and quasistatic compressive response and the process of damage evolution in ice-templated alumina materials. The improved sinterability between particles of significantly dissimilar size and morphology enabled the utilization of a high mass ratio of the particles in harnessing a markedly enhanced level of strength in highly porous ice-templated ceramics. The high volume fraction of platelets increased lamellar bridge density and resulted in dendritic morphology as opposed to lamellar morphology without platelets. All the materials showed strain rate-sensitivity, where strength increased with strain rate. Materials with highly dendritic morphology exhibited the best performance in terms of maximum strength and energy absorption capacity, and the performance improved from quasistatic to dynamic regime. Direct observation of the process of damage evolution revealed the effects of both strain rate and ratio of platelets to ultrafine particles.

Constant strain rate nanoindentation is a popular technique for probing the local mechanical properties of materials but is usually restricted to strain rates ≤0.1 s−1. Faster indentation potentially results in an overestimation of the hardness because of the plasticity error associated with the continuous stiffness measurement (CSM) method. This can have significant consequences in some applications, such as the measurement of strain rate sensitivity. The experimental strain rate range can be extended by increasing the harmonic frequency of the CSM oscillation. However, with commercial instruments, this is achievable only by identifying higher CSM frequencies at which the testing system is dynamically well behaved. Using these principles, a commercial system operated at the unusually high harmonic frequency of 1570 Hz was successfully used to characterize of the strain rate sensitivity of a Zn22Al superplastic alloy at strain rates up to 1 s−1, i.e., an order of magnitude higher than with standard methods.

Acceleration-factor (AF) equations have been developed to rapidly predict product lifetime, and the most widely used equation is Norris-Landzberg (N-L) equation. In recent years, some researchers have found that the current AF equation does not accurately predict the experimental results for thermal cyclic loading at high ramp rates; indeed, it may yield the opposite results, due to the changing effect of the solder strain rate at different ramp rates. Modifying the current AF equation to better assess product reliability has thus become an important task for researchers.

In this study, a novel AF equation was developed from a wafer level chip-scale package (WLCSP) under different thermal cyclic loadings. The frequency term used in the N-L equation was replaced with a new term in the proposed AF equation to distinguish between the effects of ramp rate and dwell time under thermal cyclic loading conditions. Proposed AF equation showed a high level of correlation with the simulation and test results for various thermal cyclic loadings. In addition, the proposed AF equation was validated by confirming the consistency of its results with experimental data on a range of packages and thermal-cycling profiles reported in the literature.

Magnesium (Mg) alloy sheet has received increasing attention in automotive, transportation, and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. To better understand the warm forming properties of magnesium alloy sheet, an accurate description of the mechanical behavior at elevated temperature is required.

In this paper, both uniaxial tensile tests and uniaxial compression tests were carried out at warm temperature for Mg AZ31B alloy sheets. The tensile tests were conducted under various strain rates and material orientations, while the compression tests only considered different material orientations. Based on the orthotropic yield criterion for hexagonal close packed (HCP) metals proposed by Cazacu et al., 2006, a viscoplasticity model has been developed to describe the initial yield anisotropy and asymmetry hardening behavior in tensile and compression of Mg sheet. This model was incorporated into ABAQUS through a user-defined material subroutine. The numerical results show a good agreement with experimental data in a large range of deformation.

To evaluate the influence of strain rate on mechanical behavior of nanocrystalline (NC) materials, a phase mixture constitutive model composed of ordered grain interior phase and plastically softer grain boundary dislocation pile up zone phase was built. Because of dissimilar properties and mismatch between the two phases, dislocation density evolution controlling mechanism based on statistically stored dislocations and geometrically necessary dislocations was analyzed and extended to NC regime to consider their disparate effects. Based on the composite model, a new stress–strain constitutive relation for strain rate-dependent behaviors was firstly established based on dislocation density evolution and strain gradient theory. The calculated data were then compared with corresponding experimental curves and strong strain rate-dependent behaviors were exhibited, which indicated that the predictions kept in good agreement with experiments. Further discussions were presented for calculations of strain rate sensitivity and activation volume for NC Ni through the proposed model.

Those patients with functionally univentricular hearts are the ones in which surgical repair so as to produce biventricular circulations is deemed impossible, despite the fact that in most instances there are two ventricles within the ventricular mass. Before the era of the Fontan procedure, the typical course of patients with such functionally univentricular arrangements consisted of cardiac failure and death within the first year of life. Despite the advent of effective palliative therapy, ventricular dysfunction remains a significant clinical problem for these patients.

We have analysed 129 stratigraphic sections from the Timan–Pechora basin, from its adjacent continental shelf and from the South Barents Sea basin, in order to determine whether existing models of extensional sedimentary basin formation can be applied to these intracratonic basins or whether new mechanisms of formation need to be invoked. The subsidence history of each section has been calculated using standard backstripping techniques. An inverse model, based on finite-duration lithospheric stretching, has then been used to calculate the distribution of strain rate as a function of time required to fit each subsidence profile. Results demonstrate an excellent fit between theory and observation. By combining our analysis with independent field-based and geophysical observations, we show that the Timan–Pechora basin underwent at least four phases of mild lithospheric stretching during the Phanerozoic (β<1.2). These phases occurred in Ordovician, Late Ordovician–Silurian, Middle–Late Devonian and Permian–Early Triassic times. Growth on normal faults, episodes of volcanic activity and regional considerations provide corroborative support for the existence of all four phases. Although less well constrained, subsidence data from the South Barents Sea basin are consistent with a similar Early–Middle Palaeozoic history. The main difference is that Permian–Early Triassic extension is substantially greater than that seen onshore. This similarity implies structural connectivity throughout their respective evolutions. Finally, subsidence modelling demonstrates that rapid foreland basin formation, associated with the Uralian Orogeny, was initiated in Permo-Triassic times and is confined to the eastern margin of the Timan–Pechora basin. Coeval foreland subsidence does not occur on the eastern margin of the South Barents Sea basin, supporting the allochthonous nature of Novaya Zemlya. The most puzzling result is the existence of simultaneous lithospheric extension and foreland loading in Permian–Early Triassic times. This juxtaposition is most clearly seen within the Timan–Pechora basin itself and suggests that convective drawdown may play a role in foreland basin formation.

The approach to the ultimate strength of metals is determined experimentally. The strength of the materials and the strain rate were determined from the free surface velocity time history, which was measured with an optically recording velocity interferometer system. The dynamic strength was measured at strain rates in the domain of 5·106 to 5·108 s−1. The necessary tension to break the metal (spall) and the very high strain rates were achieved using high-powered lasers in nanosecond and picosecond regimes. The measurements at strain rates larger than 108 s−1 were achieved for the first time. The ultimate strength of metals was calculated using a realistic wide-range equation of state. Our experiments indicate that under very fast tension processes, the dynamic strength of materials is determined not by the macroscopic defects but by atomic quantum mechanical processes described by the equation of state of the material. The rate of the process is described by the strain rate, and at strain rates higher than 5·107 s−1, the atomic forces are dominating the dynamic strength of materials.