Tear force relations

FIGURE 10.18 Tear force relations for (a) a filled elastomer without constraints (b) the same material with the tear confined to a linear path and (c) the corresponding unfilled elastomer, with and without constraints. (From Gent and Henry (1968).)... 

The experimental techniques described above of charge—discharge and impedance are nondestructive. Tear-down analysis or disassembly of spent cells and an examination of the various components using experimental techniques such as Raman microscopy, atomic force microscopy, NMR spectroscopy, transmission electron microscopy, XAS, and the like can be carried out on materials-spent battery electrodes to better understand the phenomena that lead to degradation during use. These techniques provide diagnostic techniques that identify materials properties and materials interactions that limit lifetime, performance, and thermal stabiity. The accelerated rate calorimeter finds use in identifying safety-related situations that lead to thermal runaway and destruction of the battery. 

Conventional tensile and tear tests are not particularly suitable tools for a detailed investigation of strength-related properties of. small finished components or over the thickness of a bulky product, unless the item can be sectioned to size. An alternative approach, particularly suitable for diagnostic work, involves the use of a puncture test [17]. An indentor of specified geometry is pressed into the component, and the force to cause rupture is measured at a specified penetration or over a range of depths. One suitable application is the study of aging across the thickness of a bulky product [18]. 

The puncture force F at rupture is related to the tearing energy Ti by the equation... 

Distal triceps tendon tear is an uncommon condition that mostly occurs at or close to the olecranon process of the ulna, often associated with a fleck of bone attached to the retracted tendon as a result of avulsion fracture (Fig. 8.47). The mechanism involves either forced flexion of the elbow against a contracting triceps, as occurs during a fall on an outstretched arm, or relates to a direct blow onto the olecranon process. Local steroid injection into the olecranon bursa, anabolic steroid abuse and pre-existing tendinosis may also have a role in the tendon rupture. As a rule, complete tears occur more... 

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