Mechanical fasteners, compared

Fatigue endurance is enhanced compared to that of mechanical fasteners or spot welding alone, since the stress concentration factor at the joint is reduced. The adhesive layer results in a more uniform stress field around the weld nugget. 

Adhesives as a class of materials are designed to hold substrates together by surface attachment. The products distribute a load over an entire bondline rather than concentrating stress at specific points like mechanical fasteners. Adhesive bonding also can significantly reduce part weight and assembly time compared to mechanical fasteners. 

Compared to mechanical fastening solutions, engineered laminates offer manufacturers the opportunity to work with fewer fastening components, thereby creating the ability to manufacture products with a more consistent quality in less time. In addition, engineered laminate-fastened solutions usually weigh less than finished products composed of mechanical fasteners. 

Structural timber-concrete composites (e.g., timber-concrete composite slabs and timber wall-concrete deck composite in which the connection between the two common constmction materials is made through a bonded joint). The aim is to replace traditional mechanical fasteners by an adhesive connection, which has several advantages in comparison with the former for instance, a bonded joint is able to distribute the applied load over the entire bonded joint area, resulting in a more uniform distribution of stress (compared to mechanical point connections), requires little or no damage to the adherends, adds very little weight to the structure, and has a superior stiffness and fatigue resistance. 

The skin-to-skin bond and the honeycomb sandwich bond can involve either metallic or nonmetallic composite substrates or a combination of the two. Bonding is a very attractive method of joining composite materials because their ability to withstand local stresses caused by mechanical fasteners is quite poor when compared to metals. This is especially true of composites in which the fiber orientation is unidirectional in order to increase stiffness along a specific axis. 

The basic theory of assembly, be it by mechanical fastening or any other method, is comparatively simple, as it is purely a process of joining together by one means or another two or more components to form a completed or partially... 

Despite unfavorable mechanical properties of polyethylene compared to polypropylene, PVC, ABS, and Nylon, HDPE is the most popular plastic in WPCs. Polypropylene is too tough and makes difficult to use nails and screws as fasteners at a deck installation. Polypropylene-based composites require special fastening systems. PVC is typically considered as not environmentally friendly. Other polymers are not weather stable, brittle, or expensive. 

Flax fibers have recently been investigated as reinforcement in polymeric foam matrices for current components used in the transportation industry (Fuqua et al. 2010). Despite the fact that plywood bus floorboards are chemically treated to prevent decay, they stUl require repeated replacement over the lifecycle of a transit vehicle (Vaidya et al. 2004). Mechanical testing of both flexural performance and fastener pullout capabilities of flax-fiber/soy-based PU foam composites demonstrated that they could serve as a suitable flooring replacement in mass transit vehicles. Stmctures ranging from 55% to 70% renewable material by weight with an inexpensive lower quality flax mat (i.e., 40% shive content and 60% fiber) could produce flexural strength comparable to pl3rwood with little environmental impact (Fuqua et al. 2010). 

As a result, ultra high modulus carbon fibers are preferred to others for their high stiffness/ density ratio for a low CTE compared with titanium or aluminum. Since composites are preferred to metal parts, bonding becomes the mandatory technology for fastening parts, because drilling and the bolt/nut/rivet principle require holes which affect the mechanical properties of the joint due to concentrations of loads around sectioned fibers. 

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