Experimental and Numerical Analysis of Thermomechanical Fracture Processes in Polymers Accounting for Brittle to Ductile Transition

TÜBİTAK Projesi, 2236 - Uluslararası Deneyimli Araştırmacı Dolaşımı Destek Programı, 2020 - 2022

Proje Türü: TÜBİTAK Projesi
Destek Programı: 2236 - Uluslararası Deneyimli Araştırmacı Dolaşımı Destek Programı
Başlama Tarihi: Mayıs 2020
Bitiş Tarihi: Mayıs 2022

Proje Özeti

Optimal use of materials and design of components thereof have become an important

scope of the key industrial sectors, such as automobile, aerospace, construction, electronics,

and medical industry. The associated mechanical properties, i.e. low weight and highstrength, blended with workability, manufacturability, and recyclability ultimately render

polymers, in particular thermoplastics, superior over metals. Such properties of polymers

essentially lead to the resource and energy efficiency, optimized design concepts, green and

integrated means of transportation while being environmentally friendly. Those desirable

properties of polymers, however, heavily depend on the microstructure, temperature level

and the external loading rate which can change the fracture response from brittle to ductile

and vice versa. Therefore, reaping the potential benefits of polymers brings the need for

thorough experimental and numerical investigations, i.e. a micro-structure based

thermomechanical approach to fracture in polymers. Though there have been a great deal of

an interest in those potential benefits, no study has been presented up to now on the

realization of brittle to ductile transition through a fully coupled thermomechanical fracture

model. In fact, there is a pressing need for a unique research treating the thermal,

mechanical and failure aspects concurrently, thereby providing saving of time and material,

the accurate determination of design limits without resorting to lengthy and often expensive

testing or empirical models.

In this project, we aim to develop a unified microstructure-based thermomechanical approach

for the fracture of polymers in the ductile-brittle transition zone that inherently incorporates

the rate- and temperature-dependent microstructure evolution. Particularly, following a

comprehensive experimental investigation quantifying the elastic and inelastic material

response at different loading rates and temperature levels, we will propose a new constitutive

model, which simultaneously model shear-yielding (ductile behavior) and crazing (brittle

behavior) in a unified constitutive framework. The proposed model will be extended to a fully

coupled thermomechanical setting with the help of the material parameters characterized at

various temperatures. Finally, a temperature and loading rate dependent failure criteria along

with a crack growth function will be developed within the framework of phase-field approach

to fracture