 |
Project A4: Design of structures for dynamic loading conditions | |||
 |
||||
| Project Leader: Dr. Christopher Hutchinson - Monash University | Staff/students |
|||
|
||||
| Many engineering applications require materials to perform under sustained and dynamic mechanical loadings. The use of Al in aircraft is a classic example where alternating stresses give rise to fatigue loading of the materials. Fabricating materials with the required properties for these types of applications is only part of the challenge. The properties must also be stable under the loading conditions for the expected lifetime of the material. Often this stability in properties is translated to a question of stability in microstructure and the materials scientist usually implements approaches to retard the kinetics microstructural change to solve this problem. In cases where a material is subjected primarily to thermal loadings, or even to static mechanical loads, the driving forces for microstructural change can be easily quantified and this directly suggests approaches to microstructural stabilization (such as the pinning of grain boundaries by small particles or solute segregation in nanocrystalline materials). | Hoffman, Mark |
|||
|
||||
| However, in systems subject to sustained mechanical loadings, the driving forces for microstructural change are not as easily identified. In these cases, the external input of mechanical energy must be explicitly incorporated into both questions of the driving forces for microstructural change and any approaches to stabilization of microstructure. This field is not very well developed for external mechanical forcing and consequently, neither is the design principles for stabilization of materials properties subject to fatigue or creep loadings or sustained deformation such as that experienced during an automobile crash. At present, principles based on quasi-static loadings are used; for example, assuming that designing for creep resistance is the same as designing for elevated temperature yield stress or extrapolating the strain-rate dependence of deformation under low strain-rates to very high strain-rates. Recent experiments have shown this to be incorrect. | ||||
|
||||
| This overall aim of this project is to contribute to the understanding of the fundamental principles governing microstructural change in systems subject to an external mechanical forcing. An understanding of these principles is to be used in the design of new light alloys with improved creep, fatigue and medium-high strain-rate deformation behavior. | ||||
|
||||
| This project is divided into two streams based on the mode of mechanical loading: monotonic or cyclic. The monotonic loading stream consists of two sub-projects: | ||||
|
||||
| a) | Intermediate strain-rate effects (20-1000s-1) on the deformation behaviour of light alloy systems. This project is geared towards the design of materials for applications where crashworthiness is a primary requirement. | |||
|
||||
| b) | Creep behavior of Al alloys. This project is concerned with elucidating design principles for microstructures subject to sustained and simultaneous thermal and mechanical loading. | |||
|
||||
| This project is divided into two streams based on the mode of mechanical loading: monotonic or cyclic. The monotonic loading stream consists of two sub-projects: | ||||
|
||||
| a) | Effect of grainsize and grain boundary character on the fatigue properties of light alloys. | |||
|
||||
| b) | Effect of solute and precipitates on fatigue properties of light alloys. | |||
|
||||
|
||||
|
|
|
|
|