Structural Integrity Laboratory

Structural integrity is meant by a capability of a structure to carry out the operation for which it was designed. Therefore, the safety and performance of engineering structures, components, systems and their associated materials should be considered in order to fulfill all aspects of structural integrity. One of the essential elements to achieve these targets is durability analysis. By definition, durability is the capacity of an item to survive its intended use for a suitably long period of time. Therefore, good durability minimises the cost of maintaining and replacing the item, the prevention of failures and the optimisation of automobile or component design. In Centre for Automotive Research, this sub-group is led by Prof. Dr. Shahrum Abdullah and the members are Assoc. Prof. Dr. Nordin Jamaluddin, Assoc. Prof. Dr. Mariyam Jameelah Ghazali and others.

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One of the tasks performed during durability analysis is the fatigue life assessment of components such as engine parts, suspension parts and body structures. Automotive manufacturers have made large investments in this area so as to achieve products which meet a specified fatigue life target. As example, a coil spring will experience the strain and the vibration when it was driven on any road surfaces. Physical conditions of the road surfaces such as pothole, bump or curb, are contributing to the strain and the vibration. The significant amounts of load are then transmitted to this component while it serves to maintain the contact between the wheel and the road. The higher amount of loads that were transmitted to the coil spring means that, the fatigue resistant of that component was decreased. Thus, all these important factors will be considered to affect the durability of this component.  Figure 1 shows an actual coil spring that was used in the automotive suspension system. In addition, Figure 2 exhibits a FEA-based modeling is performed using fatigue analysis software codes which can estimate failure life.

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Another research consists in this subgroup is an acoustic emission (AE) technology. This AE technique has been uniquely and firstly utilised to assess and predict the fatigue life of metallic structure and  components. Previously, other researchers have employed the AE technology to monitor and analyse the fatigue behavior of metallic materials. The fatigue behavior has been widely determined by the conventional fatigue assessment methods based on strain measurement and microstructural observation. Our research group is investigating and studying intensively  the correlation between the acoustic emisssion signals and the results of the conventional fatigue assessment due to varying load methods as well as the microstructural observation results diagnose and predict the fatigue behavior of metallic materials and components.

 

It is expected that by examining the fatigue behavior of several types of the metallic materials and components, a new algorithm for interpretation of the AE signatures can be conducted and a new method for monitoring and diagnosis of fatigue in the metallic materials and components can be developed (Figure 3). In another subject, AE technology has been successfully utilised for on-line monitoring and assess the viscosity of engine diesel. The engine oil viscosity is very important since it affects the performance of engines and prolong the engine life (Figure 4). In our investigation, the acoustic emission signals are successfully employed to quantify the viscosity of diesel engine oil which is mainly function of the in-service duration.

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