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

Cervix;Viscoelastic modeling;Gestational age;Load relaxation

Babacan, Oytun ; Wagoner Johnson ; Amy J.

关键词: Cervix;    Viscoelastic modeling;    Gestational age;    Load relaxation;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/34388/Babacan_Oytun.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Preterm birth is a leading cause of death and abnormality among newborn infants. Cervicalinsufficiency is one of the major causes of preterm birth. Unfortunately, this asymptomaticcondition remains hidden to many patients until preterm birth occurs. Accurate characterizationof the mechanical behavior of cervical tissue can enable the development of medicaldevices that can diagnose the condition of cervical insufficiency before labor begins and helpavoid preterm birth. In this study, the main focus was to develop a simple viscoelastic modelthat 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 dashpotswithout using a repetitive scheme. Same basic elements were supposed to be used only onceto investigate how simple discrete models perform in describing a complex behavior like softbiological tissue stress relaxation. For this purpose, 3, 4 and 5 element spring and dashpotmodels were developed and tested with the data obtained through uniaxial tensile stress relaxationex 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 orderto examine whether the models can capture the change in the tissue properties as pregnancyproceeds. Although both 3 element and 4 element models are able to describe the stressrelaxation behavior of the cervical tissue, the error analysis shows that 4 element modelworks best among the investigated models. 5 element models cannot be implemented to thestress 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 allmodel parameters with increasing gestational ages.