Mechanical strength properties of carbon fiber composite tubes

Carbon fiber composite materials have unique and superior properties such as light weight, good stiffness, high specific strength, high specific modulus, high temperature resistance, good fatigue resistance, and designability. Components or structures made of this material have only traditional weight. 80% of the material. In recent years, due to the application of wound CFRP pipes in aerospace, offshore platforms, underwater structures, pressure vessels, etc., the design and mechanical properties of filament wound CFRP pipes and pressure vessels have become the research focus of composite material structures at home and abroad. hot spot.

In this paper, the strength characteristics of CFRP pipes are studied through experiments, which lays a solid foundation for the further application of CFRP pipes in civil engineering. Preparation of test specimens The materials used for the test specimens are T700SC carbon fiber (Toray Corporation, Japan) and epoxy resin. The fibers are laid in longitudinal and hoop directions. The longitudinal fibers mainly provide tensile and compressive resistance, and the hoop fibers serve as the hoop compensation Strong and resistant to accidental transverse shear, the layup method is (0°, 90°) s. The experimental specimens were processed by the winding forming method. The length of a single specimen was 500 mm, and the nominal thickness of the tube was 1.6 mm. The reinforced area at both ends of the pressure tube is 100mm, the length of the test section is 300mm, the inner diameter of the tube is 150mm, the reinforced area at both ends of the tension tube is 150mm, the length of the test section is 200mm, and the inner diameter of the tube is 50mm. The ends of the tube are machined to level and reduce eccentricity.

By observing the stress-strain curve obtained by the CFRP tube compression experiment, it is found that the CFP tube prepared by this material has good compressive strength, the average strength is 230MPa, and the strain reaches 5.2×10^-3. In the experiment, there was almost no visible change before loading to 80% of the failure load, and when it reached 80% of the failure load, a crackling sound was heard, at which time the resin began to crack. The failure occurred suddenly, and a violent breaking sound could be heard, which belonged to brittle failure. By observing the cross-section, the resin was cracked, and it was found that the hoop fibers were broken and the longitudinal fibers were broken. This shows that when the CRP pipe is compressed, the load is mainly borne by the matrix, and its strength depends on the strength of the matrix. No buckling of the tube wall was found during the experiment, which was a strength failure.

Observe the stress-strain curve obtained from the tensile test of the CFRP tube. Compared with the stress-strain curve of the compression test, there is a big difference. By analyzing the strain data, it can be seen that when the deformation strain of the specimen reaches 0.005 after loading, there will be a sound of shearing and cracking. At this time, the resin begins to have micro-cracks, but it cannot be observed with the naked eye. When the strain reaches about 0.015, the resin on the tensile section Large-scale cracking, the fractured resin quits work, the load is mainly borne by the fibers, the load continues to increase, but the deformation of the specimen increases faster, and the stiffness degradation is very obvious. Until the fiber is broken, the specimen is destroyed. When broken, the tensile strength of the CRP pipe is more than 800MPa, and the strain is as large as 0.03, which shows that the CFRP pipe has good tensile properties.

Compared with steel, CFRP pipe has the characteristics of light weight and high strength. In particular, the tensile strength is over 800MPa. However, CFRP materials are brittle materials, and the compression failure shows obvious brittle fracture characteristics. When the strain of CFRP pipe is within about 0.015, the stress-strain curve changes linearly. With the visible cracking of the resin, the stiffness of the pipe is seriously degraded, and the deformation increases rapidly.


Founded in 2006, Jiaxing Longshine Carbon Fiber Products Co., Ltd. is China Custom Carbon Fiber Tubes Manufacturers and OEM Carbon Fiber Pipes Factory, located in the center of Yangtze River Delta, the state-level Xiuzhou High-tech Industrial Development Zone of Jiaxing. In recent years, we committed to the r&d and production of carbon fiber and other composite materials in the military and civil fields, including participating in the R&D and production of C919 aircraft parts, high-speed rail accessories, and several logistics support projects.
Production process: autoclave, tube rolling, molding, bag pressing, extrusion, winding and vacuum diversion assisted molding process.
Product type: tube/pipe, plate (solid/sandwich), 3D products.
In recent years, we committed to the r&d and production of carbon fiber and other composite materials in the military and civil fields, including participating in the R&D and production of C919 aircraft parts, high-speed rail accessories, and several logistics support projects. OEM custom Carbon Fiber Tubing.
We are willing to sincerely work with you, win-win cooperation, and strive to make the enterprise become the industry leading, customer satisfaction, harmonious team quality enterprise, contribute to the development of the whole industry and the needs of the country.