Drilling of hybrid composite materials in aerospace applications
To increase fuel efficiency and reduce lifecycle cost, aerospace and transportation industries have been seeking a material or material combinations, which exhibit high strength-to-density ratios and excellent mechanical properties in the extreme loading conditions. The hybrid structure of carbon fiber reinforced plastics composite (CFRP) and titanium (Ti) stack has been widely utilized due to its unique ability to withstand high stress in service. Due to the dissimilar machining characteristics of CFRP and Ti, the CFRP-Ti stack is very challenging to drill holes in the construction of a plane. The field of manufacturing processes of hybrid composite materials and their performances is the focus of this research.
Manufacturing and mechanical performance verification of glass fiber composites for marine and renewable energy systems
The integration of glass fiber reinforced composites (GFRP) in maritime use can be seen as far back as the Second World War when small personnel boats for the US Navy were first created with composite material. Immediate popularity grew when it was determined that composites were stiff, strong, durable, easy to repair, and simple to form. Since then, increasing efforts have been made to incorporate these materials into the design of various components and structures for recreational, commercial, and military craft. Now, the same technology has been applied into wind turbine blade design and manufacturing. The focus of this research is to develop manufacturing processes for GFRP products in marine/renewable energy systems applications and investigate their mechanical performances.
Fatigue Improvement process development and analysis
In aircraft structural design, one of the main goals is to increase the fatigue life and damage tolerance capability of the structures in order to minimize the maintenance costs. The cold hole expansion process is one of the most popular techniques in the fatigue enhancement processes for aircraft structures and the process produces beneficial compressive residual stresses around the hole, which retards the initiation and propagation of the crack at the hole edge. Numerical and experimental studies have been conducted to analyze crack initiation and propagation on the cold hole expension processed holes. For the automotive applications, a post-weld cold working process has been recently introduced in order to improve fatigue strength of low carbon steel and aluminum RSWs. The cold working process generates uniform and consistent large zones of compressive residual stresses in resistance spot-welded low carbon steel structures using a specially designed indentation device. This innovative technology can minimize the cost needed to improve the fatigue life of the resistance spot weld in metal structures.