Seminar by Dr. Raj Kiran and Dr. Qi Zhang

On October 6, 2023, the lectures from Dr. Raj Kiran and Dr.Qi Zhang take place in the meeting room B.

Dr. Raj Kiran presents a talk entitled "Adaptive phase-field modeling of thermo-electromechanical brittle fracture in piezoceramics via an isogeometric approach"

Abstract:

Piezoelectrics as smart materials have widespread applications in modern-day industries serving as sensors, actuators, or transducers. Predicting the failure of piezoelectric actuators and sensors under the complex thermo-electromechanical loadings is of engineering and scientific significance. Phase-field modeling has recently emerged as an effective strategy to tackle three-dimensional (3D) fracture problems under different multiphysics loading through the regularization of sharp crack topologies. This seminar aims to focus on the development of an adaptive phase-field model for the thermos-electromechanical fracture in piezoceramics where the crack phase-field evolution is considered within the framework of coupled thermo-electromechanical constitutive relationships. The study employs an efficient adaptive mesh refinement scheme within the framework of isogeometric analysis using a prescribed value of the phase-field parameter as an error indicator. In particular, the study considers thermo-electromechanical coupling to quantify the variations of temperature, electric field, and mechanical deformations on the critical fracture load in different modes of fracture. The phase-field modelling approach can efficiently capture different complex crack propagation patterns as demonstrated through several benchmark problems in 2D and 3D without using any ad hoc crack tracking algorithms. The model can provide insights into the fracture behavior of piezoceramics in thermal environments and result in more reliable material and device design.

Dr. Qi Zhang presents a talk entitled "A Coupling Approach of the Isogeometric–Meshfree Method and Peridynamics for Static and Dynamic Crack Propagation"

Abstract:

A coupling approach of the isogeometric–meshfree method and the peridynamic method is presented for static and dynamic crack propagation. The coupling approach exhibits advantages in the flexibility of modeling cracks and the exactness of geometry representation. The isogeometric–meshfree method, which adopts the moving least-squares approximations to establish the equivalence between meshfree shape functions and isogeometric basis functions, can obtain the exact geometry. The isogeometric–meshfree nodes located on the geometry can be directly coupled with peridynamic points by the balanced force principle, which is straightforward and effective. With this approach, the boundary conditions can be enforced directly using the isogeometric–meshfree method, and the surface effects of peridynamics are effectively eliminated. Moreover, the present approach is flexible in switching the isogeometric–meshfree nodes to peridynamic points and achieving adaptive coupling with the same convergence rate as the one for the isogeometric–meshfree method, which is higher than the one for the original peridynamic method. Based on the exact geometry representation, the coupling approach is further extended to crack problems with contact loading. Several representative examples are presented to validate the effectiveness of the present approach in solving static/dynamic crack problems and studying fractures caused by contact.