Constitutive equations of cyclic strain and stress softening for materials with low internal stress levels are derived from the rate theory. The study shows that over the high stress and low temperature range where the description of plastic flow in cyclic softening can be approximated with activation over a single energy barrier, cyclic strain softening is well related to stress relaxation pro...

This study has investigated the creep properties of asphaltic concrete modified with different dosages of waste polyethylene terephthalate (PET) in two different ranges of size. Uniaxial dynamic creep test at 40°C was conducted on the cylindrical specimens of the mixtures. The load was applied in two different frequencies of 0.5 and 5Hz. Creep test results showed that the accumulated strain und...

We develop a thermodynamic framework for modeling nonlinear ultrasonic damage sensing and prognosis in materials undergoing progressive damage. The framework is based on the internal variable approach and relies on the construction of a pseudo-elastic strain energy function that captures the energetics associated with the damage progression. The pseudo-elastic strain energy function is composed...

Viscoelastic relaxation processes factor into polymer performance and stability throughout an application lifetime, controlled by the polymer network structure and dynamics which occur over a wide spectrum of time scales. In this work, we detail the design and operation of an independent array of surface indenters which can measure the creep response at multiple points on a polymer substrate. S...

BACKGROUND High Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications. METHOD I...

In this paper, we apply the thermodynamic framework recently put into place by Rajagopal and co-workers, to develop rate-type models for viscoelastic fluids which do not possess instantaneous elasticity. To illustrate the capabilities of such models we make a specific choice for the specific Helmholtz potential and the rate of dissipation and consider the creep and stress relaxation response as...

Due to the importance effect of magnetic field on the history of long-term radial and circumfer-ential creep strain and radial displacement for a three-phase nano-composite exposed to an internal pressure and placed uniform temperature, the present article subject has been pro-posed. Three-phase nano-composite made of single-walled carbon nano tubes (SWCNTs)/ glass fiber (GF)/vinylester used to...

the creep behavior of basalt fiber reinforced epoxy (bfre) and glass fiber reinforced epoxy (gfre) composites was studied through tensile testing at high temperature. to study the effect of reinforcing epoxy, the micro glass powder (mgp) was added at various volume percentage into the epoxy resin in bfre composites. the initial strain for all the specimens were evaluated and compared with each ...

The purpose of this study is to evaluate the long-term vertical deformations of segmented pre-tensioned concrete bridges by a new approach. It provides a practical and reliable method for calculating the amount of long-term deformation based on creep and shrinkage in segmented prestress bridges. There are various relationships for estimating the creep and shrinkage of concrete. The analytical r...

A COUPLED CREEP-PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT-PEENED NICKEL-BASE SUPERALLOY Name: Dennis Justin Buchanan University of Dayton, 2007 Advisor: Dr. R. A. Brockman Shot peening has been employed in numerous industries for decades to impart beneficial compressive residual stresses on the surface of metal components. Compressive residual stresses retard initiation of surfa...