The combined assembly between composite automotive parts and the connection between composite parts and metal components is an inevitable problem. The composite material is anisotropic, the interlayer strength is relatively low, and the ductility is small, which makes the design and analysis of the composite joints much more complicated than the metal. The connection between the traditional metal parts of the automotive industry is not applicable to the composite materials. Connections, therefore, it is critical to understand and improve the way in which automotive composites are joined and secured.
Local stress concentration is caused by the continuity of the broken fibers. Composite joints are usually the weakest link in the overall structure, so ensuring joint strength is the key to composite structural design. Composite materials are mainly divided into three categories, namely, glued joints, mechanical joints, and hybrid joints of the two. For thermoplastic composites, there are also welding techniques. Composite joint technology design needs to be determined based on the specific use of the component and design requirements.
1 glue connection
Compared with the mechanical connection, the main advantage of the bonding technology is that there is no stress concentration caused by the opening, the structure quality is reduced, the fatigue resistance, the vibration damping and the insulation performance are good, the appearance is smooth and smooth, the bonding process is simple, and there is no electrochemical corrosion problem. However, the bonding technology also has some shortcomings, such as difficulty in quality control of the bonding, large dispersion of bonding strength, lack of reliable inspection methods, strict requirements for surface treatment and bonding process of the bonding surface. For carbon fiber composite body, glue is the main connection.
2 Mechanical connection
Mechanical connections typically use rivets and bolts and are the most common type of connection. The main advantage of the mechanical connection is the high reliability of the connection, the repeated disassembly and assembly during maintenance or replacement, the need to deal with the surface, and the impact on the environment is relatively small. The main disadvantage of mechanical joining is that it increases the quality, causes stress concentration, and causes electrochemical corrosion in contact with the composite. The comparison of the rivet connection and the bolt connection is shown in Figure 1.
3 Mixed connection
In order to improve the safety and integrity of the connection, in some important connection parts, the hybrid connection method of glue connection and mechanical connection is usually used at the same time, and the advantages of the two connection methods are fully utilized to ensure sufficient strength and high connection point. reliability.
4 Welding
Welding technology is mainly applied to thermoplastic composite parts. The basic principle is to heat the resin on the surface of the molten thermoplastic composite, and then pressurize and join them. There are three main methods of welding: ultrasonic welding, electric induction welding and resistance welding. The advantages of welding are good connection effect and short cycle, no surface treatment, high joint strength, low stress, etc.; the disadvantage is that it is not easy to disassemble, and it is necessary to add conductive materials or wires. In addition, in the molding process of the composite structural member, the metal connector can be embedded in the fiber preform, and the composite material and the metal embedded component are integrated after the molding, and the composite component can be connected by the metal embedded component to avoid Machined damage composites.
------------------------------------------------------------------------------------------------------------------
XIAMEN LFT COMPOSITE PLASTIC CO.,LTD.
Focus on (LFT-G, LFRT) R&D and production: PA, PP, TPU, PPS, PBT, PPA long glass fiber & carbon fiber continuous infiltration thermoplastic composite reinforcement series engineering plastics
If you need more information, please feel free to contact me.
Mike Lee
Email: sale02@lfrtplastic.com
Mobile phone : +86-180-5026-9764 (wechat / whatsapp/ skype)
Website ：www.lfrt-plastic.com
Add:No.27 Hongxi Road, Tiangong Chuangxin Technology Park, Maxiang Town, Xiang'an Dist., Xiamen, Fujian, China.(361000)
