Showing papers in "Mechanics of Time-dependent Materials in 2022"

Enhanced heat transportation for bioconvective motion of Maxwell nanofluids over a stretching sheet with Cattaneo–Christov flux

Abstract: The main aim of this work is to study the thermal conductivity of base fluid with mild inclusion of nanoparticles. We perform numerical study for transportation of Maxwell nanofluids with activation energy and Cattaneo–Christov flux over an extending sheet along with mass transpiration. Further, bioconvection of microorganisms may support avoiding the possible settling of nanoentities. We formulate the theoretical study as a nonlinear coupled boundary value problem involving partial derivatives. Then ordinary differential equations are obtained from the leading partial differential equations with the help of appropriate similarity transformations. We obtain numerical results by using the Runge–Kutta fourth-order method with shooting technique. The effects of various physical parameters such as mixed convection, buoyancy ratio, Raleigh number, Lewis number, Prandtl number, magnetic parameter, mass transpiration on bulk flow, temperature, concentration, and distributions of microorganisms are presented in graphical form. Also, the skin friction coefficient, Nusselt number, Sherwood number, and motile density number are calculated and presented in the form of tables. The validation of numerical procedure is confirmed through its comparison with the existing results. The computation is carried out for suitable inputs of the controlling parameters.

Experimental evaluation and uncertainty quantification for a fractional viscoelastic model of salt concrete

Abstract: Abstract This study evaluates and analyzes creep testing results on salt concrete of type M2. The concrete is a candidate material for long-lasting structures for sealing underground radioactive waste repository sites. Predicting operational lifetime and security aspects for these structures requires specific constitutive equations to describe the material behavior. Thus, we analyze whether a fractional viscoelastic constitutive law is capable of representing the long-term creep and relaxation processes for M2 concrete. We conduct a creep test to identify the parameters of the fractional model. Moreover, we use the Bayesian inversion method to evaluate the identifiability of the model parameters and the suitability of the experimental setup to yield a reliable prediction of the concrete behavior. Particularly, this Bayesian analysis allows to incorporate expert knowledge as prior information, to account for limited experimental precision and finally to rigorously quantify the post-calibration uncertainty.

Self-similar crack propagation along a viscoelastic interface in a double-cantilever beam test

Abstract: Double-Cantilever Beam (DCB) testing is a common protocol to evaluate bonded interface toughness. The data-analysis procedures are initially based on the classical Linear Elastic Fracture Mechanics (LEFM) and have been extended to deal with plastic behavior. Nevertheless, those analyses are not suitable when time-dependent behavior is involved in the crack propagation process. In this paper, an analysis of crack propagation along a viscoelastic interface during a DCB test is conducted, assuming a Standard Linear Solid (SLS) model for the adhesive. During the self-similar crack propagation regime, a steady-state stress–strain distribution is achieved ahead of the crack tip and a Eulerian description is used. A finite-difference scheme is implemented to solve the set of differential equations from which stress–strain evolutions along the bondline are determined as the specimen deforms. The crack propagation response under stationary loading conditions is then simulated and the energy-based failure criteria are evaluated comparing both local and global estimations of the Strain-Energy Release Rate (SERR).