Strength breaking

Visual and Manual Tests. Synthetic fibers are generally mixed with other fibers to achieve a balance of properties. Acryhc staple may be blended with wool, cotton, polyester, rayon, and other synthetic fibers. Therefore, as a preliminary step, the yam or fabric must be separated into its constituent fibers. This immediately estabUshes whether the fiber is a continuous filament or staple product. Staple length, brightness, and breaking strength wet and dry are all usehil tests that can be done in a cursory examination. A more critical identification can be made by a set of simple manual procedures based on burning, staining, solubiUty, density deterrnination, and microscopical examination. 

Tensile properties of importance include the modulus, yields, (strength at 5% elongation), and ultimate break strength. Since in many uses the essential function of the film may be destroyed if it stretches under use, the yield and values are more critical than the ultimate strength. This is tme, for example, where film is used as the base for magnetic tape or microfilm information storage. In some cases, the tensile properties at temperatures other than standard are critical. Thus if films are to be coated and dried in hot air ovens, the yield at 150°C or higher may be critical. 

Linear Low Density Polyethylene. Films from linear low density polyethylene (LLDPE) resias have 75% higher tensile strength, 50% higher elongation-to-break strength, and a slightly higher but broader heat-seal initiation temperature than do films from LDPE. Impact and puncture resistance are also improved over LDPE. Water-vapor and gas-permeation properties are similar to those of LDPE films. 

Breaking Strength and Elongation. The breaking strength and elongation (extensibihty) of woven fabrics are often used as quaUty-control... 

For knitted fabrics exhibiting high extensibiUty to failure, the ball burst test is recommended (ASTM D3787). A poHshed steel ball is pressed onto a rigidly held circle of knitted fabric. The force on the ball required to mpture the fabric is reported as breaking strength. 

Standard Test Methods for Steel Tire Cord. ASTM standard D2969-92 includes test methods for steel cords that are specifically designed for use in the reinforcement of pneumatic tires. It describes test methods determining steel cord constmction, break strength, elongation at break. 

Standard Test Methods for Tire Yarns, Cords, and Woven Fabrics. ASTM standard D885M-94 includes test methods for characterizing tire cord twist, break strength, elongation at break, modulus, tenacity, work-to-break, toughness, stiffness, growth, and dip pickup for industrial filament yams made from organic base fibers, cords twisted from such yams, and fabrics woven from these cords that are produced specifically for use in the manufacture of pneumatic tires. These test methods apply to nylon, polyester, rayon, and aramid yams, tire cords, and woven fabrics. 

Standard Test Method for Breaking Strength and Elongation of Cotton Fibers (Flat Bundle Method)," ASTM E144S-90, Annual Book ofASTM Standards, Vol 07.01, ASTM, Philadelphia, Pa., 1991, pp. 405—409. 

In the soldedess wrap (Fig. 3) or wire-wrap connection, a wire conductor is coiled around the back end of the separable contact, which has a square or rectangular cross section (4). The corners of the soldedess wrap post and the areas of the wire that are in contact with it are severely deformed. In a propedy made wrap, the force required to sHde the wire along the post exceeds the breaking strength of the wire. The method is suitable only for soHd wire, and special tools are used to make this connection. 

Application. In the past, the break strength of a synthetic yarn has averaged 34.6 lb. The first-stage draw ratio of the spinning machines has been increased. Production management wants to determine whether the break strength has changed under the new condition. 

Since 2.1.3.3 > 2.086, reject Hq and accept Hi. It has been demonstrated that an improvement in break strength has been achieved. 

Fiber Weight, oz/yd Thickness, in Breaking strength, Ibf/in width Elongation, % to rupture Air permeability, (ftVmin)/ft at Api = Vi in water Kp... 

Cross-breaking strength of these fasteners = X 2 X X X 2200 kg (for ordinary MS fasteners)... 

Figure 24.9. Effect of cure time on some properties of M-F mouldings. Cure temperature cellulose filled 295-308°F mineral filled 300-320°F O glass-filled material, asbestos-filled material, A cellulose-filled material (a) Cross-breaking strength (b) tensile strength (c) impact strength (d) impact strength (e) water absorption (rag), boiling water 30 min (f) cold water 24 h, 23°C ...

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