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Project title: Effect of interface debonding on constitutive response of particulate and fiber composites

Project description: In this project, we use multiscale finite element modeling and micromechanics-based homogenization schemes to investigate the effect of inclusion/matrix debonding on the macroscopic response of particulate and fiber-reinforced composites.

Project title: Multiscale cohesive modeling of failure in heterogeneous adhesives

project description: In this project, we develop and implement a multi-scale cohesive finite element framework to extract the cohesive failure properties of heterogeneous adhesives such as rubber-toughened epoxy, self-healing adhesives and other multi-functional adhesives. The figures on the right show a width-tapered double-cantilever-beam specimen used

to test the failure and healing response of a slef-healing epoxy adhesive (top) and the load-displacement curve obtained in the initial failure of the specimen (red curve) and the healed specimen (blue curve).

Cohesive modeling, in which the adhesive layer is “collapsed” to a single plane (or curve), appears as a natural way to model the response of the adhesive. Unlike “classical” cohesive models which are chosen for mathematical convenience, the multiscale cohesive framework allows to relate in a mathematically consistent way the failure processes taking place at the micro-scale to the macroscopic cohesive failure response of the adhesive system.

project title: Multi-physics design of actively cooled microvascular composites

project description: This project is motivated by the development of a new class of microvascular polymeric materials for high temperature applications. An initial implementation of this concept is shown in the figure below, which schematically presents a thermal experiment performed by B. Kozola in Prof. S. R. White’s research group. A fan-shaped microvascular network is embedded in an epoxy component, which is then subjected to thermal loading applied on the bottom side of the specimen. The evolution of the temperature in the part is monitored using an infrared (IR) camera. The set up is shown on the left figure, the temperature field in the absence of cooling fluid in the microvascular network is shown on the right.

The evolution of the temperature in the part as 5 ml/min of coolant is circulated in the microvascular network is shown in the animation. The cooling effect of the fluid (which circulated from left to right) is clearly apparent. As expected, the left side of the domain achieves a cooler temperature, as the cooling fluid heats up as it traverses the warm region.

On the numerical side, we combine a generalized finite element method developed in-house with a multi-objective/constraint genetic optimization scheme to perform the computational design of biomimetic microvascular materials with active cooling capabilities. At the heart of the problem is the ability to model in an accurate and efficient fashion the cooling effect created by complex network of micro-channels embedded in a polymeric component subjected to a variety of thermal loading. Objective functions include the flow efficiency and void volume fraction associated with the microvascular network, and the maximum temperature obtained in the thermally loaded domain. Recent activities focus on the inclusion of this technology in 3D fiber-reinforced composites to be used for high temperature applications.

project title: experimental and numerical analysis of a novel laser-induced delamination test for thin films

Project description: in this combined experimental and numerical research project, we develop a novel non-contact testing procedure to extract the fracture toughness (i.e., energy of delamination) of film/substrate interfaces found in microelectronics applications.

project title: MULTISCALE MODELING OF DAMAGE IN POLYCRYSTALLINE THIN FILMS USED IN MEMS APPLICATIONS

PROJECT DESCRIPTION: the key objective of this project is to use multiscale finite element schemes to investigate the effect of the granular microstructure in the constitutive and damage response of thin metallic films used in MEMS applications. This project involves close collaboration with Prof. Chasiotis’ group, who performs in-situ measurements of the mechanical response of these very thin films.

PROJECT title: COUPLING ISSUES IN COMPUTATIONAL AEROELASTICITY

PROJECT DESCRIPTION: the accurate and conservative treatment of load transfer across the fluid/structure interface plays a key role in the accuracy of the overall aeroelastic problem. this project aims at the development and assessment of new load transfer and temporal coupling schemes for transient fluid/structure interaction problems characterized by non-matching interface discretizations. in particular, we investigate a novel load transfer scheme, referred to as the common refinement scheme, which provides substantial improvements in the accuracy of the load transfer scheme compared with load transfer schemes available in the literature.

project title: coupled simulation of the aero-thermal-acoustic response of hypersonic vehicles

project description: in this multiphysics computational project, we aim to perform first principle simulations of coupling effects in the structural, thermal and acoustic response of thin panels present in the outer skin of hypersonic vehicles.