Yoshinori Yoshida

Influence of Processing Parameters on Bonding Conditions in Backward Extrusion Forged Bonding

In this study, conditions of metallurgical bonding between steel and aluminum in cold forging process is investigated. Two-layered cylindrical cup of the materials is produced in cold backward extrusion in five processing velocity conditions. Small tensile test specimens are cut off at the bonding boundary in the product using a wire-cutting machine and the bonding strength on the boundary is measured in tensile test using the specimens. Fractured contact surfaces are observed with an electron microscope for investigation of bonding. Finite element analyses for the backward extrusion are conducted and surface expansion ratio and interface pressure on the boundary are calculated. The influence of process conditions, extrusion velocity and surface expansion ratio and boundary pressure, on the bonding are investigated.

Influence of Layer Number on Mechanical Property of Steel Hollow Sphere Sheet Sandwich Construction

Two sheets of steel hollow sphere sheet (TEC SHEET) are laminated and its mechanical property is investigated by means of stab proof test. The construction is sandwiched by a pair of pure aluminum plates with two kinds of bonding methods. Three point bending test and compression test are conducted for the construction. As the results, stab proof strength is advanced more than that of a single layer sheet. In the bending test, bending load increases with increase of the layer in the sandwich construction. Bending mechanism is investigated and the influence of bonding method on breakage condition of the sandwiches. Compression test for the sandwich construction and foam metal filling construction is conducted and the difference of the energy consumption behavior is investigated.

Development of Metal Hollow Sphere Sandwich Construction and its Formability and Mechanical Property

In this paper, a new light weight construction is developed. The steel hollow sphere (MHS) sheet is sandwiched between two pure aluminum plates and the mechanical properties of the construction are investigated by means of compression test, bending test and stab-resistant test. As the results, the advanced specific stab-resistant strength and the plateau compression behaviour are found. In addition the damage progress inside of the construction is observed using a CCD camera. The fracture condition of the sandwiched MHS are compared with that of a conventional foam metal sandwich construction. The formability of the plate and energy absorption property are measured and the optimal construction condition is discussed.

Development of Metal Hollow Sphere Sheet and its Formability and Mechanical Property

A metal hollow sphere (MHS) sheet structure is developed and its mechanical property is investigated. We performed piercings for steel MHS and placed them on a piece of tungsten wire to make an MHS thread. MHS sheets with two kinds of construction have been developed using the thread; plain weave construction and reverse stitching construction. Their tensile property is investigated through tensile test, where advanced specific tensile strength and plateau tensile behaviour are found. Its mechanism is investigated using video and the properties compared with conventional MHS clusters. A block cluster is made from the sheet and compression property is researched by observing their breaking behaviour. The sheet is introduced into a pure aluminium tube and energy absorption through side compression is evaluated.