In the current study the nonlinear viscoelastic response of a polymer matrix composite under multiple creep/creep-recovery loading is presented. The influence of creep/creep-recovery multiple step loading in the overall strain response both viscoelastic and viscoplastic is examined and an attempt for modeling this behaviour is attempted. An increase in the parameters of nonlinearity is observed...

The viscoplastic behavior of a carbon-fiber/polymer matrix composite was investigated through two different modeling efforts. The first model is phenomenological in nature and utilizes the tensile and stress relaxation experiments to predict the creep strain. The phenomenological model was constructed based on the overstress viscoplastic model. In the second model, the composite viscoplastic be...

Local damage models are known to produce pathological mesh dependence in finite element simulations. The solution is to either use a regularization technique or to adopt a non-local damage model. Viscoplasticity is one technique which can regularize the mesh dependence of local damage model by incorporating a physical phenomenon in the constitutive model i.e. rate effects. A detailed numerical ...

Electronic power modules devices are paramount components in the aeronautical, automotive and military applications. The solder layers are the most critical parts of the module and are usually subjected in their whole life to complex loading conditions. To improve the design task, realistic thermoelastoviscoplastic and lifetime prediction models which can describe efficiently the deformation-da...

A thermomechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermomechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The da...

Available online 12 September 2016 The thermostructural response of the cooling channel of a regeneratively cooled thrust chamber employed for rocket applications can be evaluated by means of analytical and numerical methods. The heat fluxes produced by the combustion inside the thrust chamber cause elevated temperatures in the copper structure composed of ligaments separating the coolant flow ...

Constitutive equations for the multiaxial stress-strain behavior of aluminum alloy 5754 sheets were developed, based on crystal plasticity. A Taylor-based polycrystal plasticity model, a tangent formulation of the self-consistent viscoplastic model (VPSC), and an N-site viscoplastic model based on the fast Fourier transform (VPFFT) were used to fit a single slip system hardening law to the avai...

Cortical bone, as the principal structural component of the human body, functions in both a load-bearing and protective capacity. As a material, cortical bone has been the subject of mechanical investigation and characterization for well over a century, and the time dependent nature of this material’s mechanical response to loading is well documented. To model this time-dependent behavior, many...

NASA has identified the Stirling power converter as a prime candidate for the next generation power system for space applications requiring 60,000 hours of operation. To meet this long-term goal, several critical components of the power converter were analyzed using advanced structural assessment methods. Perhaps the most critical component, because of its geometric complexity and operating env...