Yukisaburo Yamaguchi

Stress distribution and strength of T-type adhesive joint with reinforcement for bending moment

Abstract The stress distribution in the adhesive layer of T-type adhesive-bonded butt joint between rigid adherends has been measured experimentally, and the equation relating the maximum stress in the adhesive layer to the bending moment applied to the joint and to the joint dimensions was derived. The equation is used to calculate the adhesive strength of a T-type joint from the measured breaking load. These strengths show reasonable agreement with experimental values. The distribution in the adhesive layer of a T-type adhesive joint with the reinforcement having the section of a right-angled isosceles triangle has been measured experimentally. The strength efficiency of the reinforcement η and the strengthening magnification of the reinforcement μ are discussed geometrically comparing with the equation. The values of η and μ measured by the experiments showed good agreement with the values obtained geometrically.

On the Compressive Strength of Plastics-Pipe against External Pressure

The effects of dimensions and supporting conditions on the compressive strength and deformation of polyvinylchloride pipes under external pressure were discussed. The following four kinds of pipe supporting conditions were used; (A) compression between two steel plates, (B) compression between a steel plate and a concave wooden block, (C) compression between two concave wooden blocks, and (D) compression between two concave hard rubber supporters. The main results obtained are as follows.(1) The relation between the compressive strength P and the dimensions of PVC pipe is given by the following formula, similar to the mid load bending for a both end fixed straight beam with a rectangular section;P=4σb·l·t2/3·Dm·c1 (a)where, l, t and Dm are the length, thickness and diameter of pipe, respectively, c1 the correction coefficient according to pipe supporting conditions, and σb the bending stress in kg/mm2. The value of correction coefficient c1 was 0.81∼1.35 for A-method, 1.35 for B-method, 8.0 for C-method and 2.3 for D-method, respectively.(2) The deflection δ under elastic deformation is given by the following formula;δ=P·Dm3/8E·l·t3c2 (b)where, E is Youngs modulus in kg/mm2 of pipe material, and c2 the correction coefficient similar to c1. The value of c2 was 2.22 for A-method.(3) It seems reasonable, therefore, that the theory of straight beam may be applied to the compressive strength and deflection of plastics-pipe under external pressure by using the correction coefficient c1 or c2.

The Effects of Carbon Fibre and PTFE Powder upon the Friction, the Wear and the Value of Limiting pv of Polyacetal

Two kinds of fillers, such as carbon fibre and PTFE powder, were used for the present study of their effects on the friction etc. of polyacetal.The contents of those fillers are 5, 10 and 25%, and length of carbon fibre are 1, 3 and 5mm, respectively.The friction and wear tests were carried out by using the Suzuki type friction tester and Itos sliding wear tester.The results obtained are as follows;(1) The kinetic frictional coefficient of polyacetal decreases with content of fillers, such as PTFE powder and carbon fibre.(2) The sliding wear amount of polyacetal containing PTFE powder is about 0.5∼0.7 times as much as that of unfilled polyacetal.(3) The value of limiting pv of polyacetal containing the fillers increases with the increase of the contents of both fillers, PTFE powder and carbon fibre, and with that of length of carbon fibre.The pv value of polyacetal containing PTFE powder is about 1.2∼2.2 times as much as that of unfilled polyacetal, and that containing carbon fibre is about 1.1∼1.6 times as much as that of unfilled polyacetal.