Clamping stresses

Fig 3.8 shows the interface shear bond strength, tb, determined from Eq. (3.7), which is not a material constant but varies substantially with embedded fiber length, L. However, to evaluate all the relevant interface properties properly, which include the interface fracture toughness, Gic, the coefficient of friction, p, and the residual clamping stress, qo, it is necessary to obtain experimental results for a full range of L and plot these characteristic fiber stresses as a function of L. More details of the... 

The normalized FAS and IFSS are shown in Fig. 4.17. Both the FAS and IFSS distributions are higher for larger values of residual clamping stress, go, (in absolute terms) for a given fiber length. Varying the coefficient of friction, p, would have similar effects on the stress distributions. The predominant effect of differential Poisson contraction between the fiber and matrix is obvious, particularly in Fig. 4.17(b), where the IFSS values at the fiber ends are several-fold the values obtained in the center. 

Fig. 4.17. Distribution of (a) normalized fiber axial stress, crf/o, and (b) normalized interface shear stress, T /(7, along the fiber axis, z/a, at a given applied stress for different residual clamping stresses 90 =-7,-10 and-13 MPa, After Kim et al. (1993b).

Fig. 6.25 The multilayer stack actuator showing one strategy for electroding to avoid clamping stresses.

Figure 3 Clamping-Stress ap compared with stress-strain-curves a) metal b) PTFE e strain, M diaphragm, BS steel, SS stainless-steel...

Holistic measurement of the entire workpiece obtaining dense volumetric data Fast inspection and reverse engineering of complex geometrical features Noncontact measurement, without probing and clamping stresses to the part Inspection of complex and internal features produced by additive manufacturing In-depth realistic visualization of the object s details... 

The normal stresses (sometimes called clamping stresses) are generated by a misfit, 5, between the radius of the fibre and the radius of the hole In the free matrix , that is the matrix in the absence of the fibre [11]. A reduction in the radius... 

Table 3.1 Predicted clamping stresses and frictional bond In fibre-cement interface with two different matrices Portland cement (PC) and Portland cement with 10% microsilica (MS) (after Stang [24])...

Fibre Modulus (GPa) fJ- Clamping stress (MPa) Frictional bond (MPa) ... 

In a review of the interfacial properties of fibre-cement composites, Ben-tur etal. [34] compiled bond strength values reported in a variety of studies and analysed the effect of fibre composition and matrix properties. A tendency for higher bond for higher modulus fibres could be observed (Table 3.3), [35-43] as expected from the analysis presented in Section 3.2.4. The fact that the data in Table 3.3 demonstrate only a trend and not a clear-cut relationship may be associated with the different production methods and curing, leading to differences in clamping stresses, which are not the result of differences in the moduli of the fibres. 

Tin lead films have been the standard (most common) tin-based plating for over 40 years and have never been shown to have any whisker growth under ambient usage conditions. High clamp-stresses on parts like bolted connectors can result in whisker growth in tin-lead films. 

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