A transientanisotropic gradientenhanced damage model with displacement smoothing for failure analysis in quasibrittle materials

It is widely recognized in engineering fracture mechanics that integral and differential forms of nonlocal damage models with a constant internal length scale suffer from an incorrect representation of failure mechanisms either by spurious damage growth or by incorrect damage initiation and propagation. In this regard, in this thesis, a...

Accelerating finite element analysis using machine learning

We study the acceleration of the finite element method (FEM) simulations using machine learning (ML) models. Specifically, we replace computationally expensive (parts of) FEM models with efficient ML surrogates. We develop three methods to speed up FEM simulations. The primary difference between these models is their degree of intrusion into the...

Towards electrochemical-performance evaluation of fiber-based batteries: Fiber-arrangement-based method and FE² multiscale framework

Conventional battery models (e.g., Pseudo-2D model) were developed especially for particle-based battery electrodes and have limitations in addressing the newly-emerging fiber-based ones. This thesis proposes numerical tools for efficient property evaluation of fiber-based electrodes and for multiscale simulation of battery electrochemical...

Discrete fiber models beyond classical applications: Rigid line inclusions, fiber-based batteries, challenges

Reinforced composites are used in many industrial and multi-functional applications. The efficiency of the reinforcements depends mainly on the aspect ratio, material properties, and the adhesion between matrix and reinforcement. Particularly, high aspect ratio fillers and inclusions have gained popularity due to their unique material and...

Atomistic Simulations of Nickel-Titanium Shape-Memory Alloys

Shape-memory Alloys (SMAs) exhibit tremendous mechanical properties owing to their reversible phase transformation between the austenitic and the martensitic phase. Out of these, equi-atomic nickel-titanium (NiTi) alloys are the most widely used SMAs for various applications since the transformation occurs close to room temperature. Advances in...

Multiscale domain decomposition analysis of quasi-brittle materials

Computational material design is progressively gaining momentum in the engineering world. Recent breakthroughs in high performance computing and emerging multiscale algorithms have facilitated the simulation of materials at different scales of observation. In particular, the multiscale study of failure phenomena becomes crucial to assess the...

Computational modelling of fibre-reinforced cementitious composites: An analysis of discrete and mesh-independent techniques

Failure patterns and mechanical behaviour of high performance fibre-reinforced cementitious composites depend to a large extent on the distribution of fibres within a specimen. A discrete treatment of fibres enables us to study the influence of various fibre distributions on the mechanical properties of the material. The numerical analysis of...

Role of microstructural geometry in the deformation and failure of polycrystalline materials

A deeper understanding of the deformation and failure mechanisms in polycrystals is of utmost importance for their reliable use as engineering materials. These mechanisms are strongly influenced by the geometry of the granular arrangement. In this work, two-dimensional intergranular quasi-static crack propagation in brittle polycrystals and...