SU1581525A1 - Method of enhancing strength of joint - Google Patents

Abstract

The invention relates to mechanical engineering, in particular, to a method for increasing the strength of joints — welded, steam, and glue dissimilar materials operating under conditions of vibration, fatigue failure, corrosion-mechanical loading, as well as brittle failure under static load. The purpose of the invention is to reduce the concentration of stresses in the marginal zone of transition from one material to another due to the uniform distribution of stresses within the joint. The internal geometry of the joint is selected depending on the elastic characteristics of the materials to be joined in such a way that a material with lower elastic properties has an angle in the range: 40 ° ≤α 2≤100 °, with α 2 + α 1 = 270 °, where α 1α 2 is the angle between the surface of the joint and the outer surface of the composite element on the side, respectively, of a material that is harder and softer in elastic characteristics. At the specified range of choice, the maximum resistance of the joints to brittle and fatigue-type damage is achieved. 6 Il.

Description

The invention relates to mechanical engineering, in particular to welded, soldered and adhesive joints of dissimilar materials, operating under conditions of vibration, fatigue failure, corrosion-mechanical loading, as well as brittle failure under the action of a static load.

The purpose of the invention is to reduce the concentration of stresses in the marginal zone of transition from one material to another due to the uniform distribution of stresses within the joints.

Figure 1 shows a design diagram modeling an edge joint zone.

materials; Fig. 2 shows dependency plots (o) for various ratios of the elastic moduli of materials; FIG. 3 is a graph where the hatched zone is the claimed material; FIGS. 4-6 are diagrams of the method implementation on various structural elements. The investigated model (figure 1) has the following characteristics: Е t / E

 C1-25; GO-2700, moreover, o (g 270 °. This scheme simulates the boundary point of the junction of dissimilar materials 1 and 2 in joints of the type of the brand or of the corner ones (Figures 4, 5 and 6). If the materials differing in elastic moduli are connected by soldering

 L

15

U1

tsD &

, -f-j.v and ". id - Y. wuMijijrb s. . t

, Wa And yU)

The relations Ej / Ej.

or gluing, with a sufficiently thin layer of solder or glue, the presence of the latter can be neglected when considering the stress fields in the concentrator zone, i.e. The stresses and strains in the indicated compounds And in the compounds with direct contact of the materials will coincide. As a result of the research, dependences were obtained at different ratios

As calculations and experiments have shown, the -v parameter is determinative for determining the breaking load. The nature of the change in the dependence v (o / a) coincides with the character of the dependence P (,). Therefore, the evaluation of the strength of the compounds with the considered concentrators can be based only on the parameter. Some of the dependences Jif (eia) are presented in Fig. 2. When analyzing these graphs, it is noted that at o (g 70 ° there is a maximum of y values). This suggests that at o (1 70 ° (therefore, 200 ° ) the lowest possible stress level will be obtained at the top of the concentrator, all other conditions being equal. It is noted that the parameter L takes stable maximum values in the range of 40 ° S0 ° "As is known, the stress concentration negatively affects the corrosion resistance of the product. Therefore, when choosing 40 ° / 2 100 ° will be reached the highest Corrosion resistance of the product (which is very important for the elements of machine parts and devices used in the chemical industry). In addition, choosing / 2 in the indicated range will maximize the resistance of these compounds to brittle and fatigue type of damage. The contact surface of the materials should be sufficiently flat and smooth, “—to avoid the occurrence of internal stress concentrations.

The proposed method can be implemented on various types of joints of dissimilar materials (T-shaped, angular, etc.) in a wide range of differences in the elastic characteristics of joined materials. The method is simple to implement and does not require additional processing of the product.

Claims (1)

Invention Formula The method of increasing the strength of joining dissimilar materials during gluing, welding, brazing or obtained by welding, in which in the marginal zone of the joint of materials the angles of preliminary cutting of each material are selected taking into account the elastic characteristics of the materials to be joined, characterized in in the marginal zone of transition from one material to another due to the uniform distribution of stresses inside the joints, the cutting angles of each material in the specified zone I choose t of the following ratios: 40 ° Ј cd 4 100 °, and about + about / 2 270 °, where 1 and o (r - angles between the surface of the joint and the outer surface of the composite element on the side, respectively, of a hard and soft material according to the elastic properties. one 1 FIG. FIG. four Editor L. Veselovska Compiled by Z. Khaustova - Tehred L. Oliynyk Proofreader T. Paliy Order 2056 Circulation 625 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 FIG. five 2 b FIG. 6 Subscription