Composite material multi-nail and double-shear connection failure prediction method based on three-parameter characteristic curve

Abstract

The invention provides a composite material multi-nail and double-shear connection failure prediction method based on a three-parameter characteristic curve. The composite material multi-nail and double-shear connection failure prediction method comprises the following steps of: (1) designing and preparing a test piece of a tensile, compression and shear characteristic size test according to parameters of geometry, a material, a laying layer and the like of a multi-nail and double-shear connection key hole of a composite material; (2) carrying out a static-force tensile test to obtain a tensile fracture load of an opening laminated board, an extrusion fracture load of a carrying hole laminated board, and a shearing fracture load of the carrying hole laminated board; (3) calculating tensile, compression and shear characteristic sizes according to the fracture loads; (4) acquiring the three-parameter characteristic curve based on the tensile, compression and shear characteristic sizes, wherein the curve passes through a tensile characteristic point, an extrusion characteristic point and a shearing characteristic point of the key hole; and (5) predicating a failure mode and a fracture load of a multi-nail and double-shear connection structure of the composite material based on the three-parameter characteristic curve. The composite material multi-nail and double-shear connection failure prediction method disclosed by the invention is applicable to multi-nail and double-shear connection failure prediction of the composite material in engineering application, and the failure mode and the fracture load of the connection structure can be accurately predicated by considering the shearing characteristic size.

Description

technical field [0001] The invention relates to failure prediction of composite material multi-nail double-shear connection structure, and is suitable for composite material multi-nail double-shear connection structure widely used in aerospace vehicles. Background technique [0002] The connection structure of advanced composite materials is the weak link in the overall structure of composite materials, and its strength directly affects the bearing capacity of the overall structure of composite materials. Composite material connections are mainly divided into adhesive connections and mechanical connections. Mechanical connections are further divided into single-shear connections and double-shear connections. The double-shear connections can withstand larger loads due to the absence of eccentric bending moments and have wider applications. At present, in the main load-bearing structure of composite materials of aircraft, mechanical connection is still the main connection meth...

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Problems solved by technology

[0007] The classical characteristic curve only passes through the tensile and compressive characteristic points, and does not consider the influence of the shear characteristic points. There are cases where the failure mode is misjudged and the ultimate load prediction result is completely wrong.

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