Linear and nonlinear behavior of viscoelastic thin plates subjected to uniform distributed loading

Dissertant

Husayn, Sabah Khammas

University

University of Technology

Faculty

Department of Mechanics and Equipments Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2006

English Abstract

The behavior of viscoelastic material has been studied for both polyester polymer and composite polyester polymer.

A creep test is performed to distinguish the linear and nonlinear behavior of viscoelastic from the equation of creep compliance.

The stress relaxation modulus is determined from the experimental creep compliance.

A FORTRAN power station program was built to assemble the derived equations of theoretical deflection, stress and strain for each node of thin plate viscoelastic material.

The program includes three boundary conditions for plate supports and uniform distributed load.

Both linear and nonlinear behavior has been used in this program.

A two FEM programs code is developed for linear and nonlinear viscoelastic behavior depending on the stress relaxation modulus.

A Newton Rap son method is used to solve the nonlinear system of equations for both theoretical and FEM in the nonlinear behavior.

Small stress gives a linear behavior and this may be transmitted to the nonlinear behavior for higher stresses.

Hence, the distributed load must be chosen so as to give a linear or nonlinear behavior.

The deflection variation of plate has the same curve shape for creep compliance with time.

In general, the deflection increases with time and a good agreement has been observed comparing the experimental results with both the theoretical and FEM results.

A good agreement has been observed from the proposed models for nonlinear behavior and the temperature effects.

A small percentage error of (2-5 %) has been observed comparing the theoretical and the FEM results.

This error may has an alternative values for the nonlinear behavior due to the iteration used to find the final correct results.

The deflection rate decreases during time.

The deflection of plate depends on the ratio of plate dimensions.

Also the temperature effects have been studied and showed that polyester and its composite has sensitive effects hence increasing the temperature results in increasing the deflection with time.

Decreasing the thickness of the plate gives an increase in the deflection of thin viscoelastic plate and its rates for the same time period.

A composite viscoelastic material shows a higher strength during time compared to the same polyester for both linear and nonlinear behavior.

Main Subjects

Mechanical Engineering

Topics

• Mathematical models

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-306304