Crazing is usually a precursor of the brittle fracture of glassy polymers. In this paper, an optical technique is presented to quantify the crazing dominated creep damage that occurs on a stressed transparent glassy polymeric sheet of polymethyl methacrylate (PMMA). The specimens, with various sections, are loaded for a predefined period of time under a constant load at room temperature, and th...

PURPOSE To demonstrate a Scheimpflug-based imaging procedure for investigating the depth- and time-dependent strain response of the human cornea to inflation testing of whole eye globes. METHODS Six specimens, three of which with intact corneal epithelium, were mounted in a customized apparatus within a humidity and temperature-monitored wet chamber. Each specimen was subjected to two mechani...

The classic Kachanov-Rabotnov isotropic creep damage constitutive model has been used in many situations to predict the creep deformation of high temperature components. Typically, the secondary creep behavior is determined by analytical methods; however, the tertiary creep damage constants are found using a mixture of trial and error and numerical optimization. These methods require substantia...

Alkali Silica Reaction (ASR) is known to be a serious problem for concrete worldwide, especially in high humidity and high temperature regions. ASR is a slow process that develops over years to decades and it is influenced by changes in environmental and loading conditions of the structure. The problem becomes even more complicated if one recognizes that other phenomena like creep and shrinkage...

To capture the mechanical response of Ni-based materials, creep deformation and rupture experiments are typically performed. Long term tests, mimicking service conditions at 10,000 h or more, are generally avoided due to expense. Phenomenological models such as the classical Kachanov–Rabotnov (Rabotnov, 1969, Creep Problems in Structural Members, North-Holland, Amsterdam; Kachanov, 1958, “Time ...

A steady-state creep law for rocksalt, describing the two parallel mechanisms of dislocation creep and fluid-enhanced grain-boundary diffusion creep, has been used in numerical models of salt diapirism, to study the effective viscosity of rocksalt. Typical models included a 3-km-thick sedimentary layer on top of 1 km of rocksalt. The grain size of the salt has been varied between 0.5 and 3 cm a...

the changes in viscoelastic properties of potatoes (tubuls agria) stored at 4 ˚c for 4 months were modeled and evaluated by using the creep-recovery test. cylindrical specimens with 15 mm in diameter and 35 mm long were used. the samples were allowed to deform gradually under the constant stress (110 kpa) for about 30 min. after removing the load, the sample recovery was registered. deformation...

This chapter constitutes an introduction to creep and to the creep response of Aluminium and its alloys. Its major goals are: to provide basic information on creep and its mechanisms to give a description of the more extensively used mathematical relations among creep variables (time, stress and temperature) to illustrate the creep response of pure Aluminium and of Al-Mg alloys to provide a syn...