The Eindhoven University of Technology (TU/e) has the following vacancy
PhD student "Predictive modelling of interfaces in fiber-reinforced thermoplastics"
in the section Polymer Technology, Department of Mechanical Engineering
The PhD student position is available in the section Polymer Technology, and will be supervised by prof. Leon Govaert, and dr. Hans van Dommelen.
The research activities of the section Polymer Technology concentrate on the fundamental understanding of various macroscopic problems in the processing and use of polymer components and products. An important challenge is the establishment of a direct link from processing conditions to mechanical performance; a task that requires the combination of a number of vastly different disciplines, including elements of computational rheology, solid-state rheology, and polymer physics and mechanics. The section has a unique research infrastructure, both from an experimental and computational perspective. The Mechanical Testing Lab offers a large capacity of testing equipment for short-term (impact) and long-term testing (static and cyclic fatigue).
Fiber-reinforced semi-crystalline thermoplastics
Thermoplastic composites offer the potential for lightweight solutions, can be produced rapidly and also can be recycled effectively. Micromechanical prediction of the performance of thermoplastic composite parts requires an interface model that accurately captures the short and long‐term performance of interfaces formed in assembly. The thermoplastic matrix gives rise to two different failure mechanisms; one plasticity controlled, governing the mechanical response on short time scales, and the other crack‐growth controlled, responsible for damage evolution and failure on long time scales (fatigue). An essential challenge is the prediction of the development of the interfacial strength during processing; both for short‐term, as well as long‐term loading. For the unfilled matrix, only a limited amount of interdiffusion is required to enable co‐crystallization, resulting in a fast evolution of the fracture toughness to the ultimate level of the bulk. However, the interfacial fatigue resistance is then still far inferior to that of the bulk performance. The long‐term performance clearly develops on a different (larger) time scale, and bulk performance is only fully restored when the entanglement network is fully recovered, requiring deeper interdiffusion. The kinetics of this interface healing should be captured and modelled to enable adequate prediction of the interfacial fatigue performance on the basis of the fusion conditions.
Aim of the PhD project
This project aims at developing a constitutive interface model that adequately captures the fatigue crack growth kinetics of the interphase region focusing on the influence of maximum load, stress ratio and frequency in different modes. Starting point will be the characterization of the fatigue crack growth kinetics of the matrix over the time scales required. This component is essential for the micromechanical simulations of the composite. The development of the interface crack growth resistance during fusion in the process of healing of matrix‐matrix interfaces, and in interfaces formed by welding, is a critical component that will be experimentally evaluated for the main joining techniques. The outcome will be a cohesive zone-type matrix interface model that can be fed with input on processing conditions to predict the local interface performance.
The simulations will be validated on the weld tests performed here, where different weld conditions, affecting the interface properties are considered.
Qualification of applicant
Talented, enthusiastic candidates with excellent analytical and communication skills holding a university degree (MSc, with high grades) in Mechanical Engineering, Materials Science or Applied Mathematics are encouraged to apply. A strong interest in mechanics of materials is required. Experience in multi-scale modelling, micromechanics, and experimental mechanics are of benefit.
Do you recognize yourself in this profile and would you like to know more? Please contact
prof. Leon Govaert, l.e.govaert[at]tue.nl.
For information about terms of employment, click here or contact HRAdvicesME[at]tue.nl.
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