Principle of interlayer shear performance test of 350g high-strength carbon fiber needle felt

Basic concept of interlayer shear performance
Interlayer shear performance refers to the ability of composite materials to resist shear stress at the interlayer joint. For 350g High Strength Carbon Fiber Needle Felt, the bonding strength between the fiber and the matrix and between the layers in its multilayer structure is the key factor determining the overall performance of the material. The quality of interlayer shear performance directly affects the material's anti-delamination ability, impact resistance and fatigue life in practical applications.

Necessity of interlayer shear performance test
In practical applications, 350g High Strength Carbon Fiber Needle Felt often needs to withstand complex stress states, especially in high-tech fields such as aerospace and automotive industries. The material not only needs to have excellent tensile, compression and bending properties, but also needs to have good interlayer bonding strength. Interlayer shear performance test can effectively evaluate the shear resistance of materials at the interlayer joint, providing a scientific basis for the design, optimization and application of materials.

The basic principle of the short beam shear method
The short beam shear method is a commonly used interlaminar shear performance test method. Its basic principle is to generate the maximum shear stress at the span center of the specimen through three-point bending loading, thereby inducing interlaminar shear failure. The specific principle is as follows:

In the short beam shear test, the specimen is placed on two support rollers, and the loading roller is located above the center of the specimen. When the loading roller applies a load downward, the specimen is bent and deformed at the span center. During the bending process, the upper surface of the specimen is subjected to compressive stress, the lower surface is subjected to tensile stress, and the maximum shear stress is generated near the neutral axis.

According to the theory of material mechanics, under the three-point bending loading method, the shear stress distribution inside the specimen is parabolic, and the maximum shear stress occurs near the neutral axis. For multi-layer structural materials such as 350g High Strength Carbon Fiber Needle Felt, the shear stress at the interlaminar joint is concentrated, which is easy to cause interlaminar shear failure.

When the loading load reaches a certain value, the specimen undergoes shear failure at the interlaminar joint near the neutral axis. This failure mode is manifested as separation between layers, rather than fracture of fibers or matrix. By recording the load and displacement data at the time of failure, the interlaminar shear strength can be calculated.

Calculation method of interlaminar shear strength
The interlaminar shear strength is a key parameter for evaluating the interlaminar bonding strength of materials. Its calculation formula is: interlaminar shear strength is equal to three times the failure load divided by four times the product of the width and thickness of the specimen. Through this formula, the interlaminar shear strength of 350g High Strength Carbon Fiber Needle Felt can be accurately calculated, providing a quantitative basis for the performance evaluation of the material.

Advantages of short beam shear method
As a classic interlaminar shear performance test method, the short beam shear method has the following advantages: easy operation, simple test equipment, easy sample preparation and test process; reliable results, through the three-point bending loading method, it can effectively induce interlaminar shear failure, and the test results have high reliability; wide range of application, this method is suitable for interlaminar shear performance testing of various composite materials, including 350g High Strength Carbon Fiber Needle Felt.

Key factors in the test
In the interlaminar shear performance test, the following key factors should be noted to ensure the accuracy and reliability of the test results: sample size, the length, width and thickness of the sample must be prepared strictly in accordance with the standard requirements, and the size deviation will affect the distribution of shear stress; loading rate, too fast or too slow loading rate will affect the test results, and a constant loading rate must be set according to the standard requirements; sample alignment, the placement of the sample in the fixture must be accurately aligned to avoid eccentric loading leading to test errors; failure mode observation, the failure mode of the sample must be observed after the test to ensure that the failure is caused by interlaminar shear, not other factors (such as tensile or compression failure).

The significance of interlaminar shear performance test
The interlaminar shear performance test provides an important basis for the design and application of 350g High Strength Carbon Fiber Needle Felt: material optimization, through the test results, the influence of different process parameters on the interlaminar bonding strength can be evaluated, providing direction for material optimization; quality control, the test data can be used for quality control in the production process to ensure stable material performance; application evaluation, according to the interlaminar shear strength, it can be judged whether the material is suitable for specific working conditions, such as high shear stress environment.