Examining viscoelastic response of pregnant rat cervical tissue using 3, 4, and 5 element spring and dashpot models

Preterm birth is a leading cause of death and abnormality among newborn infants. Cervical insufficiency is one of the major causes of preterm birth. Unfortunately, this asymptomatic condition remains hidden to many patients until preterm birth occurs. Accurate characterization of the mechanical behavior of cervical tissue can enable the development of medical devices that can diagnose the condition of cervical insufficiency before labor begins and help avoid preterm birth. In this study, the main focus was to develop a simple viscoelastic model that can be used for describing the stress relaxation phenomenon of the rat cervical tissue. The intention was to develop a successful model from linear springs and viscous dashpots without using a repetitive scheme. Same basic elements were supposed to be used only once to investigate how simple discrete models perform in describing a complex behavior like soft biological tissue stress relaxation. For this purpose, 3, 4 and 5 element spring and dashpot models were developed and tested with the data obtained through uniaxial tensile stress relaxation ex vivo experiments on the pregnant rat cervical tissues with gestational ages of 15, 17, 19 and 21 days. The experimental data from pregnant rat cervices are preferred in order to examine whether the models can capture the change in the tissue properties as pregnancy proceeds. Although both 3 element and 4 element models are able to describe the stress relaxation behavior of the cervical tissue, the error analysis shows that 4 element model works best among the investigated models. 5 element models cannot be implemented to the stress relaxation curve due to the hyperbolic functions present in their governing equations. The analysis of variance results of the working models showed a significant decrease in all model parameters with increasing gestational ages.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2012

Author dc:creator

• Babacan, Oytun

Contributors dc:contributor

• Wagoner Johnson, Amy J.

• Cervix
• Viscoelastic modeling
• Gestational age
• Load relaxation

Statement dc:rights

• Copyright 2012 Oytun Babacan

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/34388

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/34388