Research Activities

Micromechanics

In Micromechanics, materials and systems are represented at the microscale by mathematical models which explicitly incorporate features of the microstructure such as second phase or reinforcing particles, voids, defects, microcracks, grain boundaries and crystal structure. Modelling at this level gives great insight into the real physical processes that occur in materials which dictate overall mechanical performance of engineering and industrial components. Micromechanics also provides the Micro-Macro link for the overall performance to be understood and predicted. Micromechanics set in the context of computer based numerical solution methods generates a new field, namely, Computational Micromechanics.  At MICRU, use is made of advanced constitutive theories, such as Crystal Plasticity theory, in microstructural modelling.

Example: Automotive and Aerospace Applications

Figure 1: Finite Element microstructural model of an Al-SiC Metal Matrix Composite;

contour plot of crystallographic plastic strain.

Example: Medical Device Applications – Cardiovascular Stent

Figure 2: SEM image of a 316L stainless steel cardiovascular stent strut.

Figure 3: (top) grain geometry for microstructural model of the stainless steel cardiovascular stent strut in Figure 2,

and (bottom) a contour plot of crystallographic plastic strain in the stretched strut.

Previous research projects have focused on the following topics (funded by EU and Industrial sources).

Metal Matrix Composites (MMCs):

• Al alloy - SiC and Alumina particulate reinforced
• Computational modelling and experimental texting
• Deformation, strengthening and failure
• Static loading, isothermal and thermomechanical fatigue loading
• Simulation of forming processes

Hardmetals:

• WC-Co conventional and gradient hardmetals
• Computational modelling and microscale experimental observation (SEM)
• Focus on ductile fracture in Co binder phase
• Development of microscale failure criteria
• Design of gradient structure for improved performance

Wear:

• Development and calibration of macroscale models to predict wear behaviour for thin solid lubricant type coatings
• Determination of the mechanisms of wear in a thin coated substrate.

Current micromechanics based research activities, focused on biomechanics and medical device applications, are being performed within the Biomechanics Research Cluster at the National Centre for Biomedical Engineering Science (NCBES) www.nuigalway.ie/ncbes/research/biomechanics.htm