Compression deformation

Resistance to axial compressive deformation is another interesting property of the silk fibers. Based on microscopic evaluations of knotted single fibers, no evidence of kink-band failure on the compressive side of a knot curve has been observed (33,35). Synthetic high performance fibers fail by this mode even at relatively low strain levels. This is a principal limitation of synthetic fibers in some stmctural appHcations. 

In compression, of course, the strength is greater. Most ceramics are about fifteen times stronger in compression than in tension, for the reasons given in Chapter 17. For ice the factor is smaller, typically six, probably because the coefficient of friction across the crack faces (which rub together when the ceramic is loaded in compression) is exceptionally low. At stresses below 6 MPa, ice loaded in compression deforms by creep at 6 MPa it crushes, and this is the maximum stress it can carry. 

For [001] and [IlO] orientations where no stress is resolved onto <110] ordinary slip, <101] superlattice slip is observed up to the peak temperature. <101] dislocatiom predominantly lie along their screw orientation up to the peak temperature. This is consistent with the recent results of TEM observations on [001] si"gle crystals by Stucke et al. [9]. At temperatures below the peak, CRSS is much higher for the [001] orientation than for the [IlO] orientation. However, both the peak temperature and peak stress are lower for the former orientation than the latter. TTie lower peak temperature for the [001] orientation is associated with the occurrence of twiiming of the lll <112]-type above the peak temperature. Such twinning can not occur for the [IlO] orientation in compression. Deformation of [Il0]-oriented crystals above the peak is carried by slip on 111 <112]. 

The compressive data are of limited design value. They can be used for comparative material evaluation and design purposes if the conditions of the test approximate those of the application. The data are of definite value for materials that fail in the compressive test by a shattering fracture. On the other hand, for those that do not fail in this manner, the compressive information is arbitrary and is determined by selecting a point of compressive deformation at which it is considered that a complete failure of the material has taken place. About 10% of deformation are viewed in most cases as maximum. 

Balanced construction In woven RPs, equal parts of warp and fill fibers exist. Its construction is one in which reactions to tension and compression loads result in extension or compression deformations only, and... 

Fig. 2 Compression set (elastic recovery under compressive deformation) at 70 °C for an ethyl-ene-LAO random copolymer, flexible polyvinylchloride (f-PVC) thermoplastic polyurethanes (TPUs), and thermoplastic vulcanizates (TPVs)...

Inoue, M. and Norimoto, M. (1991). Permanent fixation of compressive deformation of wood. In Proceedings of the International Symposium on Chemical Modification of Wood (Kyoto), Takahashi, M. (Ed.), pp. 45-50. 

Change in length of a sample in uniaxial tensile or compressive deformation divided by its initial length... 

Note 3 For elastomers, which are assumed incompressible, the modulus is often evaluated in uniaxial tensile or compressive deformation using X - as the strain function (where X is the uniaxial deformation ratio). In the limit of zero deformation the shear modulus is evaluated as... 

Fig. 17 a Dependence of the repulsive interaction distance between the albumin (Alb)-fixed tip and the photograft-polymerized surface of DMAm on the photoirradiation time. A magnification of the plot within 60 s is shown in the inset, b Dependence of compressive force of the DMAAm graft-polymerized layer on its compression deformation... 

The ISO rotary flexometer and the Firestone both operate by superimposing a cyclic shear deformation onto a static compressive deformation but the cyclic action of the two machines is not the same. The ISO apparatus is derived from the St Joe flexometer, which at one time was included in the ASTM standard (up to 1962). 

Peleg, M. 1985. A note on the various strain measures at large compressive deformations. J. Texture Studies. 15 317-326. 

Crazing Creep Fine cracks on surface of a material. Compressive deformation occurring over time in both cured and uncured polyurethane, resulting from the application of a constant load or stress. 

Fig. 5.18 (a) Iso-PED (J/m2) curves obtained from unconfined compressive deformation... 

Fig. 5.19 The effect of consecutive unconfined compressive deformations on the temperature increase of a PS cylinder initially at 26°C. The first s — 1 deformation increases for sample temperature by 37°C the second starting from 26 + 37 = 63 °C, increases it to 97°C, close to Tg. [Reprinted by permission from M.H. Kim, Ph.D. Thesis, Department of Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ (1999).]...

Fig. 10.13 Melting of low density polyethylene (LDPE) (Equistar NA 204-000) in a starve-fed, fully intermeshing, counterrotating Leistritz LMS 30.34 at 200 rpm and 10 kg/h. (a) The screw element sequence used (h) schematic representation of the melting mechanism involving pellet compressive deformation in the calender gap (c) the carcass from screw-pulling experiments. [Reprinted by permission from S. Lim and J. L. White, Flow Mechanisms, Material Distribution and Phase Morphology Development in Modular Intermeshing counterrotating TSE, Int. Polym. Process., 9, 33 (1994).]...

C. G. Gogos and B. Qian, Plastic Energy Dissipation during Compressive Deformation of Individual Polymer Pellets and Polymer Particulate Assemblies, Adv. Polym. Tech., 21, 287-298 (2002). 

The heat transfer problem just discussed can be solved in a fashion similar to the one used in Section 5.3, to yield T(z, t). In principle, once the temperature field is known in the preform at any time before fr, the plunger force can be calculated. The preform can be taken as a solid that slips at the mold surface and has a temperature-dependent compressive modulus. At any time t < tf, each layer of the preform will deform by an amount such that (a) the force on every layer of thickness Az is the same (and equal to the unknown quantity), and (b) the sum of the compressive deformations of all the layers equals the deformation imposed on the preform by the plunger at the given time. The force... 

At the same time electrochemically oxidized and thermally treated MWNT considerably change strength of the composite materials and mode of its deformation. The strength decreases while compression-deformation plot acquires S-like shape... 

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