Papers by Keyword: Pull Out Force

Abstract: Nut embedded disc grinding wheels, also known as disc grinding or F-Type wheels, are required for many production jobs. Nut pull-out is a common problem encountered in disc grinding wheels. The present work proposes a simple fixture, using which the integrity of the nut in the grinding wheel can be assessed. This method can be adopted by any grinding wheel manufacturer for a realistic estimate of nut pull out strength in double disc grinding wheels.

Abstract: A scanning electron microscope (SEM) was used for observing the microstructures of a Mactridae shell. It showed that the shell is a kind of natural bioceramic composite, which consists of aragonite sheets and organic matrix with laminated structure. It also showed that there are various reinforced microstructures in the shell, which include a kind of lambdoidal one. The maximum pullout force of the lambdoidal reinforced microstructure, which is related to the fracture toughness of the shell, was analyzed and compared with that of a conventional 0°-structure based on their representative models. The result indicated that the maximum pullout force of the lambdoidal reinforced microstructure is markedly larger than that of the 0°-structure, which was experimentally verified.

Abstract: Bone is a kind of biomaterial in nature. It behaves favorable strength, stiffness and fracture toughness which are closely related to its fine microstructure. SEM observation on a shankbone shows that the bone is a kind of natural bioceramic composite consisted of hydroxyapatite layers and collagen matrix. The observation also shows that the hydroxyapatite layers consist of many hydroxyapatite sheets and are arranged in a parallel distribution. The fracture toughness of the bone is analyzed based on the representative model of the microstructure of the bone and the idea of maximum pullout force. The analytical result shows that the long and thin shape as well as the parallel distribution of the hydroxyapatite sheets improves the maximum pullout force of the sheets and the fracture toughness of the bone.

Abstract: The microstructure of a Fragum unedo shell is observed with a scanning electronic microscope (SEM). It shows that the shell is a kind of bio-ceramic composite consisting of aragonite and collagen protein layers. The observation also shows that the aragonite layers consist of thin and long aragonite sheets. A kind of particular herringbone structure of the aragonite sheets is found. In the structure, the aragonite sheets in an arbitrary aragonite layer make a crossed angle against that in its neighboring aragonite layers. Based on the SEM observation the comparative experiments in the maximum pull-out forces of both the herringbone and conventional 0°-structures are conducted. It shows that the maximum pull-out force of the herringbone structure is markedly larger than that of the 0°-structure, and the larger the crossed angle is, the more the maximum pull-out force of the herringbone structure will increase compared with that of the 0°-structure.

Abstract: Electromagnetic compression of tubular profiles with high electrical conductivity is an innovative joining process for lightweight structures. The components are joint using pulsed magnetic fields which apply radial pressures of up to 200 MPa to tubular work pieces causing a symmetric reduction of the diameter with typical strain rates of about 104 sec-1. Since there is no contact between components to be joined and the joining machine, any damage of component’s surface can be avoided. The load, which the joint can transmit, is strongly dependent on the residual stresses in the region of the joint. In the present article, the influence of charging energy, gap width before joining and diameter on the development of the residual stresses is analysed using geometry changes during splitting of the components. Besides, the contact zone between the components is analysed and the pullout force of the joints is determined by tensile tests. This allows the evaluation of correlations between joining process, state after joining and mechanical properties.

Abstract: Electromagnetic Compression of tubular profiles with high electrical conductivity is an innovative joining process for light weight structures. The components are joined using pulsed magnetic fields which apply radial pressures of up to 200 MPa to tubular work pieces causing a symmetric reduction of the diameter with typical strain rates of about 104 sec-1. This process avoids any surface’s damage of the workpiece because there is no contact between the components and the forming tool. The load, which the joints can transmit, strongly depends on the process parameters. Of them, the charging energy and initial gap between components are the most important. In the present article, the influence of these two parameters on the joint’s characteristics, material’s microstructure and the mechanical properties is analyzed. The strength of the joint is determined by tensile tests and by measurements of the residual stresses. Finally, conclusions for the joint design are given.