Tensile Shock Physics in Compressible Thermoviscoelastic Solid Medium

This paper addresses tensile shock physics in thermoviscoelastic (TVE) solids without memory. The mathematical model is derived using conservation and balance laws (CBL) of classical continuum mechanics (CCM), incorporating the contravariant second Piola-Kirchhoff stress tensor, the covariant Green’s strain tensor, and its rates up to order n. This mathematical model permits the study of finite deformation and finite strain compressible deformation physics with an ordered rate dissipation mechanism. Constitutive theories are derived using conjugate pairs in entropy inequality and the representation theorem. The resulting mathematical model is both thermodynamically and mathematically consistent and has closure. The solution of the initial value problems (IVPs) describing evolutions is obtained using a variationally consistent space-time coupled finite element method, derived using space-time residual functional in which the local approximations are in hpk higher-order scalar product spaces. This permits accurate description problem physics over the discretization and also permits precise a posteriori computation of the space-time residual functional, an accurate measure of the accuracy of the computed solution. Model problem studies are presented to demonstrate tensile shock formation, propagation, reflection, and interaction. A unique feature of this research is that tensile shocks can only exist in solid matter, as their existence requires a medium to be elastic (presence of strain), which is only possible in a solid medium. In tensile shock physics, a decrease in the density of the medium caused by tensile waves leads to shock formation ahead of the wave. In contrast, in compressive shocks, an increase in density and the corresponding compressive waves result in the formation of compression shocks behind of the wave. Although these are two similar phenomena, they are inherently different in nature. To our knowledge, this work has not been reported in the published literature.

Tensile Shock Physics in Compressible Thermoviscoelastic Solids with Rheology

The paper addresses tensile shock physics in compressible thermoviscoelastic solids with rheology i.e., in compressible polymeric solids. Polymeric solids have elasticity, dissipation mechanisms and relaxation phenomena due to the presence of long chain molecules in the viscous medium. Thus, the main focus of this investigation is to study how the presence of rheology influences tensile shock physics compared to the tensile shock physics in thermoelastic solids with same elasticity and dissipation but without rheology. A traveling stress wave in polymeric solids leaves nonzero stress signature behind it that naturally influences density. Complete relaxation of the nonzero signatures of stress and associated density change depends upon viscosity of the medium, Deborah number, strength of the stress or velocity wave etc. These aspects of the tensile shock physics in TVES with rheology are investigated in the paper. The mathematical model for finite deformation, finite strain is derived using CBL and CCM, and constitutive theories are derived using conjugate pairs in the entropy inequality and the representation theorem. This mathematical model is thermodynamically and mathematically consistent and has closure. The solution of the IVPs described by this mathematical model related to tensile shock physics in TVES with memory are obtained using space-time coupled finite element method based on space-time residual functional for a space-time strip with time marching. p-version hierarchical space-time local approximations with higher order global differentiability in hpk-scalar product spaces and use of minimally conforming spaces ensure that all space-time integrals over space-time discretization are Riemann. This facilitates more accurate description of the physics in the computational process. Model problem studies are presented to illustrate various aspects of tensile shock physics in compressible TVES with rheology.

Tetraploid induced by physical and chemical methods in Jinjiang oyster（Crassostrea rivularis）

In order to induce tetraploid into Jinjiang oyster (Crassostrea rivularis), embryos were treated with physical (cold or heat shock) and chemical (chlorpromazinum or traditional Chinese medicine)methods in the first 3 min before the cleavage of zygotes or at the onset of the first cleavage of one or two eggs. Measurements show that the induction rates of tetraploid in the embryos inspected are 28%, 30%, 28. 4% and 35. 8% for heat-shock (39℃, 3 min),cold-shock (10℃, 3min),chlorpromazinum (0. 375 mg/dm3, 10 min) and traditional Chinese medicine (50 g/dm3 )extract (57 cm3, 10 min),respectively. The tetraploid induction rate in the larvae treated with traditional Chinese medicine is 32. 5%.It is evident that the induction rate of tetraploid in embryos insected at an early stage is the most remarkable when treated. with traditional Chinese medicine.