Fastener flexibility

Cross-sectional area of the fasteners Fastener flexibility... 

Fastener stiffness (inverse of fastener flexibility) slope of an experimentally determined curve of R as a function of... 

Load transferred by a fastener Design bearing strength Distance from e.g. to fastener i in x-direction Distance from e.g. to fastener i in y-direction Empirical constants in expressions for fastener flexibility Shank diameter of fastener i in a fastener group Rotation of fastener i due to torsional moment... 

Jarfall (reference 5.14) suggested the constant C be called the fastener flexibility. The inverse of the fastener flexibility is denoted as the fastener stiffness K xp ... 

To determine Kffe from Equation (5.32), Kmesh and Kexp must be known. Kme is determined from a finite element analysis of the source model using rigid spring elements. Kexp is usually unknown and must be estimated from analytical or semi empirical models. There exist several semi-empirical expressions for the fastener flexibility (the inverse of the fastener stiffness Kexp) which are used in the industry. Those presented by Huth (reference 5.12) are valid for both metallic and composite (carbon FRF) members. The fastener flexibility for a single-lap joint from (reference 5.12) is ... 

Huth,H Influence of the fastener flexibility on the prediction of load transfer and fatigue life of multiple-row joints, in Fatigue in Mechanically Fastened Composite and Metallic Joints,... 

BP. These nitrile alloy membranes are compounded from PVC, flexibilized by the addition of butadiene—acrylonitrile copolymers, PVC, and other proprietary ingredients. Typically reinforced with polyester scrim, NBP membranes are 1 mm thick and have a width of 1.5 m. They ate ptedominandy used in mechanically fastened roofing systems. NBP membranes exhibit excellent teat and puncture resistance as well as good weatherabihty, and remain flexible at low temperatures. They ate resistant to most chemicals but ate sensitive to aromatic hydrocarbons. The sheet is usually offered in light colors. The physical characteristics of NBP membranes have been described (15). 

Water and brine pumps may be isolated with flexible connectors. For small-bore pipes, these can be ordinary reinforced rubber hose, suitably fastened at each end. For larger pipes, corrugated or bellows connectors of various types can be obtained. In all cases, the main pipe must be securely fixed close to the connector, so that the latter absorbs all the vibration. Flexible connectors for the refrigerant usually take the form of corrugated metal hose, wrapped and braided. They should be placed as close to the compressor as possible. 

EPDM is by far the most widely used material in the ballasted roofing system construction. Because of EPDM s flexibility, very large sheets of up to 10,000 square feet (929 m2) can be delivered to the job site in compact rolls that offer reduced labor on the roof in the seaming process. The typical EPDM sheet size used in ballasted systems is 12 by 30 m and 1.1 mm thick. EPDM is also widely used in both the fully adhered and mechanically fastened roofing systems. In these constructions, both 1.1- and 1.5-mm thick material is used with widths from 2.1 to 15 m. A majority of the installations use nonreinforced sheet, although reinforced membrane can also be used in all of the system types. The majority of the reinforced sheets go into mechanically fastened systems. 

CPA. Copolymer alloy membranes (CPAs) are made by alloying high molecular weight polymeries, plasticizers, special stabilizers, biocides, and antioxidants with poly(vinyl chloride) (PVC). The membrane is typically reinforced with polyester and comes in finished thicknesses of 0.75—1.5 mm and widths of 1.5—1.8 m. The primary installation method is mechanically fastened, but some fully adhered systems are also possible. The CPA membranes can exhibit long-term flexibility by alleviating migration of the polymeric plasticizers, and are chemically resistant and compatible with many oils and greases, animal fats, asphalt, and coal-tar pitch. The physical characteristics of a CPA membrane have been described (15). 

A leather belt was still in place on the body and was fastened with a metal buckle and keeper. Both of these were cast in a nonferrous alloy and were originally plated with a copper alloy. The leather was in good condition, being intact but lacking flexibility due to burial. The metal had corroded to form a corrosion crust that was consistent with burial duration and conditions. The shoes were intact, consisting of leather uppers, synthetic sole and containing the remains of dyed cotton socks and the small bones of the foot. 

Thermal expansion and the resultant pipe stresses must be considered in any piping system design. For example, if the temperature changes from 50 to 600°F, the increase in length would be 4.9 in. per 100 ft for steel pipe and 7.3 in. per 100 ft for brass pipe. This amount of thermal expansion could easily cause a pipe or wall to buckle if the pipe were fastened firmly at each end with no allowances for expansion. The necessary flexibility for the piping system can be provided by the use of expansion loops, changes in direction, bellows joints, slip joints, and other devices. 

The reactive hotmelt adhesives retain a high level of flexibility and dynamic load-bearing capacities even after crossUnking and are used to join plastics to one another as well as to wood (furniture industry), glass (construction industry), aluminum (sandwich elements), and painted surfaces. Typical applications include window casement sheathing, foil laminations, clip fasteners, bookbinding, textile... 

Wire is thin, flexible continuous product of circular cross section. Wire may be soft or cold drawn to high strength. Wire is made from wire rod which is drawn down to make wire. Wire rod is used to make fasteners... 

Cloth fastened to breeching Cloth or similar flexible material... 

According to Brandon Willis of Uniseal, Inc., With many of these substrates, mechanical fasteners have been abandoned in favor of adhesives, which provide a two-fold advantage. First, they provide a process and design flexibility that mechanical fasteners simply do not. Second, the adhesives themselves are lighter in weight than mechanical fasteners such as rivets, especially in large-quantity uses such as trailer sidewalls. Willis discusses Composite Challenges on pp. 17-19. 

---