Suguru Sugimori

Photoviscoelastic analysis of thermal stress in a quenched epoxy beam

This paper reports on a procedure for photoviscoelastic analysis where the axes of principal stress, principal strain and polarization of light coincide in the presence of a large temperature change. More specially, the transient-thermal stress and strain due to stress in an epoxy beam subjected to quenching from both the upper and lower surfaces, are determined using the time-temperature-equivalent law for stress, strain and birefringence. The transient-thermal stress and strain in the beam were determined experimentally using hereditary integrations from the measurement of the transient temperature and birefringence due to the quenching of the beam. The transient thermal stress and strain were also calculated theoretically using the linear-viscoelastic theory. The experimentally determined thermal stress agrees closely with the theoretical results. The experimentally determined strain agrees qualitatively with the theoretical values. Thus, it is concluded that the photoviscoelastic technique is useful in analyzing the proposed problem.

Fundamentals Of Photoviscoelastic Technique For Analysis Of Time And Temperature Dependent Stress And Strain

Polymeric materials show remarkable time and temperature dependent viscoelastic behaviors, which are quite different from elastic ones, under certain conditions, for example, at the temperature ranging from the glassy state to the rubbery. Although photoelasticity is an useful experimental method for the analysis of elastic stress, it is not applicable for analysis of time and temperature dependent viscoelastic stress and strain.

A simplified optical method for measuring residual stress by rapid cooling in thermosetting resin strip

Recently, thermosetting plastics have been more widely used in parts requiring high reliability, such as precision mechanical elements of electric apparatus, structural members on the aircraft and so on. The residual stress and shrinkage of thermosetting plastics in molding are becoming a serious problem these cases. Therefore, it has become necessary to investigate the growth mechanism, method of prevention and evaluation of residual stress and strain.

Simplified Optical Method for Measuring Stress and Strain in Viscoelastic Body.

A simplified optical method based on photoviscoelasticity is proposed for measuring the transient stress and strain generated in a two-dimensional photoviscoelastic body. First, the fundamental equation for the simplified optical method is derived from the relation ships between the stress, strain and birefringence in the two-dimensional photoviscoelastic body based on the linear photoviscoelastic theory. As an example of the application, transient stress, strain and birefringence produced by nonproportional loading under a constant temperature are measured by using the simplified optical method. Next, these stresses and strains under the same conditions are theoretically calculated based on the linear viscoelasticity. The effectiveness of the simplified optical method is assessed by comparing the results.

Residual stress and deformation of PMMA due to thermoviscoelastic behavior.

This paper is concerned with the residual stress and deformation of PMMA beam produced by rapid cooling from both sides under various temperature conditions. The theoretical value of the residual stress and deformation of this beam are calculated by using the fundamental equations based on the linear viscoelastic theory. On the other hand, the specimens were then actually subjected to rapid cooling under the same temperature conditions. After rapid cooling, the residual stress and deformation are measured. The experimental and theoretical results are then compared and discussed.