Production structural joints

Although most common applications of adhesives in the wood industry are related to the manufacture of engineered wood products, their use to produce assembled structural joints is becoming more and more important in the building industry, particularly in the context of structural repair and reinforcement. 

The liquid acrylics form a further group of unsaturated reactive resins and these are now available as two-part mixed or unmixed products. Compared with polyesters they are a relatively recent addition to the range of adhesives potentially suitable for structural joints. Many are based on the monomer methylmethacrylate which is polymerised by the addition of a small quantity of initiator or hardener. 

Hazards can also result from production and distribution activities that engineers plan or manage. It is not always possible to constmct or produce items the way they appear on design drawings. A specified fastener or connector may be unavailable. A substitute one may weaken a structural joint. Replacing one chemical with another may introduce toxic or... 

The considerably improved mechanical properties of SIFCON can be exploited in various structures or in their particular regions, where locally improved properties may modify overall structural behaviour, such as shields against projectiles or radiation, repair of outdoor structures, joint connections in structures exposed to seismic action or possible explosions, pre-cast impact resistant panels, walls of treasuries, etc. The practical applications of SIFCON are restricted to these special structures probably there are some barriers on information about executed structures and details of their design, and such restrictions are compulsory for both designers and contractors. Also, the question as to whether the high additional costs of materials and construction are balanced by the performance of the product should be answered in every case. 

Of all NTD methods for quality control of materials, products, welded and soldered joints the most informative and perspective are radioscopic ones that enable to obtain a visual image of an inner structure of a tested objects in real time under any projection. 

In order to control the tightness of welded joints on various products and structures, a range of units and complexes for control of pipes, pipelines, tanks, protective casings were developed, in particular, a set of put-on vacuum chambers for sheet structures. 

S = basic allowable stress for materials, excluding casting, joint, or structural-grade quahty factors E = quahty factor. The quahty factor E is one or the product of more than one of the following quahty factors casting quality factor Ec, joint quahty factor Ej (see Fig. 10-164), and structural-grade quahty factor E, of 0.92. 

A snap joint is economical in two respects it allows the structural member to be molded simultaneously with the molded product, and it allows rationalizing the assembly, compared with such other joining processes as screws. Table 3-4 provides a comparison of its advantages and disadvantages. Some examples of the various types and their design considerations are shown in Figs. 3-23 to 3-25. 

The DSHEA allows manufacturers to make certain kinds of claims for their products (called structure/function claims ), but not specific health claims. For example, a manufacturer can say that its product "supports the immune system," "promotes healthy joints," or "reduces stress." It cannot say that it "reduces the pain of arthritis," "improves the health of a person with a compromised immune system" (such as HIV infection), or "works as effectively as Prozac . Manufacturers also have to include the following disclaimer on their labels and packages ... 

Composites Both UV and EB cures are employed for the production of wood composite materials and in fiber-reinforced composites for aircraft and aerospace applications. The EB technology has been successful in the manufacture of large structures that exceed the size of autoclaves, and in curing adhesive joints in cases where uniform radiation can be provided more easily than uniform heat. In industrial and consumer applications, multiple combinations of different reinforcing fibers can be co-cured in one cycle by EB with considerably lower residual stresses than those introduced by thermal cure.16... 

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