Tensile bar

Small and long specimens of tensile bar shape specimens have their major change in dimensions in the necked-down section. The specimen is mounted between a pendulum head and crosshead clamp on the pendulum of an impact tester. The pendulum is released and it swings past a fixed anvil that halts the crosshead clamp. The pendulum head continues forward, carrying the forward portion of the ruptured specimen. The energy loss (tensile impact energy) is recorded, as well as whether the failure appeared to be of a brittle or ductile type. 

ISO 294-2 1996 Plastics - Injection moulding of test specimens of thermoplastic materials -Part 2 Small tensile bars... 

Forced sinusoidal uniaxial tension and shear imposed by mechanical drive to tensile bar or double-lap shear specimen... 

Solution blends of 20-25% by weight were formed in DM Ac, with conventional dry spinning and film casting techniques used to produce blend fiber and film, respectively. Blend powders were prepared by precipitating the dope with a non-solvent (water). All materials were extensively washed in methanol or water to reduce residual solvent to less than 1 wt %. Neat resin tensile bars and plaques were compression molded from both powder and fiber. 

Mechanical tests were carried out with an Instron 1123 mechanical test machine operated at a crosshead speed of 2 mm/min. Moduli were determined using rectangular bar specimens that were pulled in tension using an extensometer to obtain accurate strain measurements. Initial slopes of the stress-strain curves represent the moduli. Strength measurements were made using ASTM Type V tensile bars (cut after the composites were produced) that were pulled in tension, and the maximum tensile stresses attained were taken as the strength values. 

The installation to simulate sliding friction shown on the right-hand side of Fig. 4 was developed at our institute. In design it resembles a classic pin-on-disc tribometer. Here, a rectangular polymer particle cut from tensile bars with a length of 10 mm, a width of 4 mm and a thickness of 4 mm is pressed onto a rotating disc with a defined normal force... 

M.F. Horstemeyer et al Numerical, experimental, nondestructive, and image analyses of damage progression in cast A356 aluminum notch tensile bars. Theor. App. Fracture Mech. 

Polymer Morphology and Failure Mechanisms. A failed tensile bar of unmodified piperidine-cured epoxy resin shows shear deformation before tensile failure when strained slowly (0.127 cm/sec). We could not produce stable crazes in specimens of unmodified epoxy resins. At all stress levels, temperatures, and conditions of annealing only fracture occurred after shear band formation. The failure to observe crazes in unmodified epoxy resins may be explained by a fast equilibrium condition which exists between crazing on loading and recovery on unloading. 

An electron micrograph of a fracture surface of a CTBN-toughened epoxy resin is shown in Figure 5. This CTBN is particular in that the in situ formed particles are less than 0.5 /zm in diameter. A tensile bar of this system also shows shear deformation which indicate that the small particles have not interfered with the shear deformation characteristic of the unmodified resin. The deformation bands are nearly parallel to the planes of maximum shear stress—i.e., roughly at 45° to the principal... 

The morphology of a small particle size, toughened system has been further explored by examining the fracture surfaces of the stressed tensile bars. An electron photomicrograph of a replica of this surface showed a deformation band extending diagonally (Figure 6). The rubber par-... 

Finally, stress whitening after neck formation in tensile bars of crystalline polymers imder plane stress conditions may be associated with some kind of craze-II-formation, in analogy to the corresponding observations in amorphous PC. 

In the following sections the fatigue lifetime results for fom polymers will be described. In aU cases, the samples were pre-notched at knit lines by using doublegated tensile bar injection molded samples. 

The objective of this test method is to measure the cohesive stress and the time to failure of a crystalline polymer craze layer under rapid, uniform extension. The method is an impact variant of the Full Notch Creep test used by Fleissner [12], Duan and Williams [13], Pandya and Williams [14] and others. The specimen (Fig. 2), a square-section tensile bar, is injection moulded. At the mid-plane of the gauge length a sharp, deep circumferential notch reduces the cross-section to about one fifth of its original area. This notch plane is formed by a moulded-in, hardened steel washer. Specimens were injection moulded at 210°C into a warm (100°C) mould and air cooled to 40 C using a hold pressure of 45-50 bar. 

Figures 2-4 and 5-7 give raw flow, width, and thickness direction TMA data for an M-350 center-gated plate and neat 300 series tensile bar, respectively.

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