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Friction performance of paper-based materials for wet clutches in automotive automatic transmissions is influenced by the entire structure of the material, which is characterized by a combination of porosity and visco-elasticity. In the clutch plate engagement process, the coefficient of friction is higher when the porosity of the material is higher. In this paper, visco-elasticity of the material was measured by a testing apparatus which was originally designed and built. It has become clear that the compressive visco-elastic deformation increases as the porosity becomes higher. The relationship between the compressive visco-elastic deformation of the material and the friction torque curve of the clutch plate was also analyzed. It was found that the friction torque curve of a clutch plate is influenced by the visco-elasticity of the material as well as the porosity.

The friction performance and thermal resistance of paper-based wet friction materials used for automotive automatic transmissions are influenced by the material structure formed as a result of the combination of porosity and resiliency. In our previous papers, the effects of porosity on the frictional performance and the thermal resistance were characterized by Stribeck Diagrams based on continuous sliding test data, and were also discussed with reference to torque curves and temperature measurements by an SAE No. 2 friction tester. In this paper, the effects of porosity on the mechanical strength and the fatigue of paper-based friction materials were studied for practical paper-based materials. The mechanical strength like shear strength, etc. of the material tends to decrease as the porosity increases. The fatigue life of the material, when the repeated compression and shear force are applied at the same time, was also discussed.

One of the major characteristics of paper-based wet friction materials used for clutch plates and brake bands in automotive automatic transmissions is represented by the combinations of resilient and porous properties. In a previous paper, the relationship between porosity and the friction characteristics of a paper-based friction material was studied, based on Stribeck Diagrams and the torque curves obtained from an SAE No. 2 friction tester. In this paper, the effects of porosity on the frictional performance and thermal resistance of a paper-based friction material were studied, for practical paper-based friction materials, the contents of which are varied but the geometries are the same as used in real applications. It was found that the thermal resistance and the friction performance are influenced by the porosity of the material.

One of the major characteristics of paper-based wet friction materials used for clutch plates and brake bands in automotive automatic transmissions is represented by their resilient and porous properties. This specific characteristic is considered to govern the tribological behavior between a paper-based friction material and a mating steel surface. In this paper, the effects of porosity and resiliency on the friction characteristics and heat resistance of paper-based friction materials were studied. Significant direction was obtained by the experimental data of this study, which may be adapted to the design of friction plate materials.