A Method for Determining I-type Delamination Bridging Law of Composite Materials Based on Modified Beam Theory
A technology for composite materials and determination methods, applied in the fields of electrical digital data processing, instruments, design optimization/simulation, etc., can solve problems such as lack of universality, equipment errors, etc., and achieve the effect of avoiding calculation costs and reducing test devices
Active Publication Date: 2022-03-25
BEIHANG UNIV
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Problems solved by technology
This method is easy to implement but requires constant adjustment of the camera focal length to focus on the crack tip position during the test, which undoubtedly introduces equipment errors
Looking at the above types of technologies, although they can obtain relatively accurate results, they lack versatility. In engineering practice, it is hoped to propose a relatively simple bridging law determination scheme
Method used
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[0029] Implementation example: Determination of the I-type layered bridging rule of the glass fiber / EPON 828 resin matrix composite material unidirectional laminate test piece.
[0030] 1. Geometric description:
[0031] The thickness of the unidirectional laminate DCB test piece is 4.45mm, the width is 25mm, and the length is 150mm. Laminate layup order is [0°] 24 , the material properties of the unidirectional tape are: E 1 =35.25GPa, E 2 =E 3 =10.82GPa, G 12 =G 13 =G 23 =4.28GPa, ν 12 =v 13 =v 23 = 0.47.
[0032] 2. Carry out the I-type delamination test of the composite laminate, and measure its P-δ curve. Proceed as follows:
[0033] (A) Mount the DCB sample on the MTS testing machine by using the quick-mounting hinge clamp, and ensure as much as possible after the mounting is completed.
[0034] The sample is in a straight state without any distortion;
[0035] (B) Adjust the testing machine to the displacement control mode, carry out the DCB static tensile...
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Abstract
The invention relates to a method for determining the type I delamination bridging law of a composite material based on the modified beam theory, comprising the following steps: (1) carrying out a type I delamination test of a composite material laminate, and measuring its P-δ curve; (2) ) Establish the two-dimensional modified beam mechanical model of the sample under the I-type load; (3) input the P-δ curve, material basic properties, and geometric dimensions into the above-mentioned model calculation program, perform iterative calculations in Matlab software, and determine the layered length a, Initial crack tip opening displacement δ * and the energy release rate G Ic ; (4) establish G Ic and δ * The relationship between, and then get the bridging law σ g (δ * ). The present invention is applicable to the determination of the bridging law in the I-type delamination expansion process of composite material laminates under any ply angle, and its advantages include: (1) this law only needs to use the P-δ curve of the sample as input, and does not It is necessary to observe the crack position, which reduces the test equipment; (2) it is realized by Matlab program, and the calculation cost is low; (3) it can be used to determine the I-type bridging law of composite laminates at high temperature.
Description
technical field [0001] The invention relates to the determination of the bridging law in the layered expansion process of a composite material laminate under the action of an I-type load, and is suitable for a resin-based composite material laminate widely used in the structure of aerospace vehicles. Background technique [0002] Due to their excellent mechanical properties such as high specific strength, specific stiffness, and corrosion resistance, fiber-reinforced composites are widely used in aerospace structures. However, due to its weak interlayer properties, it is prone to delamination, resulting in severe structural damage without any external signs. Therefore, accurate modeling of the delamination behavior of fiber-reinforced composites is crucial in structural design. However, fiber reinforcement and delamination of materials are often accompanied by large-scale fiber bridges. The existence of fiber bridges makes the stress distribution at the crack tip extremely ...
Claims
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IPC IPC(8): G06F30/23G06F113/26G06F119/14
Inventor 赵丽滨曹天成马晨曦骈瑢
Owner BEIHANG UNIV