Prof. Kikuo Kishimoto
Abstract: Modern machines and structures are composed of various types of materials to realize required various demands. Multi-material structures become common and effective design methodology needs to be developed to treat complex problem of multi-materials design. In order to satisfy the design requirements and ensure the safety and reliability, it is important to understand the mechanical characteristics of materials to be employed. Bi-material system is basic element in multi-material structures and the performance of this system strongly depends on the strength of interface. Understanding the interface strength is crucial issue.
In this presentation, several mechanics of material researches relating to multi-material structures are presented such as characterization and modeling of the mechanical behaviors of the materials which are used for automobile components. The materials studied are the aluminum alloys and polymer materials and their performances are investigated under impact loading and repeated loading. Various approaches of interfacial mechanics are also reviewed. Molecular dynamic approach, singular stress approach, energy release rate approach and cohesive zone model approach are introduced and their characteristics are examined. As an example of multi-material structures, multilayer structures composed of adhesive layer is picked up. In electric devices, thin film multi-layer systems, those are composed of metals, ceramics and polymers, are commonly used and the reliability is strongly dependent on interfacial adhesion between these dissimilar materials. Several testing methods for adhesive films are presented such as adhesion test, peeling test, Nano-indentation test and probe tach test. The characteristic parameters such as energy release rate is examined