Transverse mechanical loading

Mechanical Load. Static mechanical load by strain leads to stretching of random-coil polymer chains in the direction of sample elongation and chain compression in the orthogonal directions. The value of the residual dipolar and quadrupolar couplings is increased by the mechanical load, and moreover, the distribution of the correlation times is also modifled. Therefore, many NMR parameters sensitive to the residual dipolar couplings and slow motions can be used for characterization of the local strain-stress effects in heterogeneous elastomers (158,160,161,179). Dynamics mechanical load leads to sample heating where the temperature distribution in dynamic equilibrium is determined by the temperature-dependent loss-modulus and the thermal conductivity of the sample. Because transverse relaxation rate (approximated by the T2 relaxation) scales with the temperature for carbon fllled SBR, a T2 map provides a temperature map of the sample. Such temperature maps have been measured for carbon-black filled SBR cylinders for different filler contents and mechanical load (180). 

The condition for the maximum twinniug suppression is fulfilled for example for the quartz bar of the orientation (XYa) 150° for the transversal piezoelectric effect. The mechanical load is applied in the direction of rotated length axis at this time. Electrodes cover the surfaces perpendicular to the xi -axis. Condition Eq. (7.8) cannot be fiilfilled for the quartz elements for the longitudinal piezoelectric effect at all. The longitudinal piezoelectric coefficient is equal to zero for such orientations. Practical apphcation must be designed in order to get the twiiming suppression as high as possible simultaneously with sufficient piezoelectric coefficient. 

The process of estimating and the change in the shape (deflection from the known geometry) based on the known mechanical properties and the mechanical load closely resembles that used in the example of the twisted rod. In the case of small strains, dimensional analysis produces a correct solution with a precision up to a dimensionless constant. The maximum stress, is directly proportional to the load force, P, and to the longitudinal linear parameter, 1 it is inversely proportional to the transverse linear parameter (thickness), b, and represents some kind of a function of the beam thickness f h) (P/E)(l/b)f(h). 

Favorable conditions are present, if either the sample is flat and stays broader than the X-ray beam, or if the material is a fiber with a circular cross-section which is crossed in transverse direction by an oblong X-ray beam. The first mentioned case can easily be realized, if the sample is a tensile bai- of sufficient breadth. In this case, only the sample thickness is changing as a function of load. In the second case, to a first approximation, the intersection between fiber and beam profile yields a truncated cylinder, V, and the cylinder diameter is varying upon mechanical loading of the fiber. 

In this research, a 3D finite element model of human tibia, based on the real geometry of tibia, was created to investigate the effect of different mechanical properties of bone on the stress analysis under a transversal impact load. Also, the time of maximum amounts of stress has been taken into account for each material property during the impact cycle. Using the real geometry of tibia is an advantage of this work in comparison with other similar studies also the mechanical properties used for the construction of the model were chosen to be close to those of real bone tissue [4]. 

In this research, by using a real geometric model of tibia, according to its complex and unique geometry, the effects of different mechanical properties of tibia on the stress analysis under a transversal impact load has been investigated. The maximum stress was seen in the case of viscoelastic model of tibia while the minimum was found with the transversely isotropic property. In agreement with previous studied [7 and 8], the maximum amount of stress reached by the transversely isotropic model of tibia was closer to the results of theoretical and experimental works by other researchers. The dependency of the viscoelastic material property to the time caused the maximum stress to be seen in the last increment of the impact cycle. But, for the elastic behavior of tibia, the maximum stress was seen in the increment with the maximum applied force. The stress relaxation was seen by a reduction in the maximum amount of stress just after the impact load was over because of the constant strain rate in the tibial shaft. 

The strain-invariant polymer failure model (SIFT) permits the superposition of separate analyses for shear and induced peel loads. There is no interaction between the two failure mechanisms. While the need for this has been minimized through sound design practice (gentle tapering of the ends of the adherends to minimize the induced peel stresses, as explained later), the new model puts this technique on a secure scientific foundation and also accommodates any applied transverse shear loads. 

J. E. Ashton, Clamped Skew Plates of Orthotropic Material Under Transverse Load, in Devebpments in Mechanics, Vol. 5, The Iowa State University Press, Ames, Iowa, 1969, pp. 297-306. 

Apart from the conditions of load transmission from fiber to matrix, the anisotropy of mechanical characteristics is also due to the considerable anisotropy of the fibers themselves in the longitudinal and transverse directions, especially in the case of fibrous reinforcements of polymeric nature [154]. 

In a super-strong PE fibre the chains lie nearly completely stretched, and are thus loaded under optimal conditions. They must, however, transmit the mechanical stress on each other, which can only happen via transverse bonds. These are relatively weak binding forces (London-Van der Waals bonds), so the number of these bonds should be made as large as possible, which means very long chains. 

Detailed modeling of a porous material under compression is a challenging task of applied structural mechanics. The reduced compression model employed in the current study is based on the unidirectional morphological displacement of solid voxels in the GDL structure under load and with the assumption of negligible transverse strain. The reduced compression model is detailed in our recent work.33 However, with the reduced compression model, it is difficult to find a relation between the compression ratio and the external load. The compression ratio is defined as the ratio of the thickness of compressed sample to that of the uncompressed sample. Nevertheless, this approach leads to reliable 3-D morphology of the non-woven GDL structures under compression. Figure 17a shows compressed, reconstructed non-woven GDL... 

S. Jannson and F. A. Leckie, Mechanical Behavior of a Continuous Fiber-Reinforced Aluminum Matrix Composite Subjected to Transverse and Thermal Loading, Journal of the Mechanics and. Physics of Solids, 40, 593-612 (1992). 

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