Experimental compliance method

Experimental Compliance Method (for Linear Elastic Behavior)... 

In the BS and ISO methods, additionally an experimental compliance and a corrected beam theory analysis are specified for the determination of Qc- The experimental compliance method is based on Berry s method (Berry 1960) and is given by ... 

Gie values have been deduced using simple beam theory (SBT), corrected beam theory (CBT), and the experimental compliance method (ECM))... 

Considering the 3-ENF test, first may be deduced using the experimental compliance method. If a relationship between the compliance and crack length is assumed of the form ... 

A number of methods have been applied to evaluate the experimental data recorded during the tests, and they may be classified into two types compliance method and direct fracture energy method. 

By contrast, the "rigid" polymer foams exhibit linear-clastic behavior up to fracture in tension and therefore can be evaluated in terms of the parameters and A"u. Although there are no standard procedures for this. Fowlkes I94] has given the experimental details of the compliance method of determining OV- for a rigid polyurethane (PU) foam. Briefly, the method uses Eq. 22 ... 

In principle, the relaxation spectrum H(r) describes the distribution of relaxation times which characterizes a sample. If such a distribution function can be determined from one type of deformation experiment, it can be used to evaluate the modulus or compliance in experiments involving other modes of deformation. In this sense it embodies the key features of the viscoelastic response of a spectrum. Methods for finding a function H(r) which is compatible with experimental results are discussed in Ferry s Viscoelastic Properties of Polymers. In Sec. 3.12 we shall see how a molecular model for viscoelasticity can be used as a source of information concerning the relaxation spectrum. 

The quasielastic method as developed by Schapery [26] is used in the development of the viscoelastic residual stress model. The use of the quasielastic method is motivated by the fact that the relaxation moduli are required in the viscoelastic analysis of residual stresses, whereas the experimental characterization of composite materials is usually in terms of the creep compliances. An excellent account of the development of the quasielastic method is given in [27]. The underlying restriction in the application of the quasielastic method is that the compliance response of the material shows little curvature when plotted versus log time [28]. Harper [27] shows excellent agreement between the quasielastic method and direct inversion for AS4/3510-6 graphite/epoxy composite. For most graphite/thermoset systems, the restrictions imposed by the quasielastic method are satisfied. 

The master curves obtained from specimens cast from tetrahydro-furan solution at 2 and 4% strain, respectively, are slightly different. These differences, however, are probably within the experimental error. An idea of the reproducibility can be obtained from Figure 4, which shows the master curves of the creep compliances obtained on specimens cut from two sheets of Kraton 102 cast from benzene solution. Although the method of preparation appeared to be identical, there are noticeable differences between the two curves. Even larger differences exist between these curves and the master curve obtained from the relaxation data after conversion to creep. Again, there were no apparent differences in the method of preparation of the sheets from which the specimens for the relaxation and creep tests were cut. 

It is generally recognized and accepted that analytical methods must be suitable for the intended use. Furthermore, EU Directives 85/591/EEC, 89/397/EEC and 93/99/ EEC state that analytical procedures for compliance testing with food laws are to be carried out on the basis of validated methods. Method validation is known as the process used to confirm that a procedure is fit for a particular analytical purpose. This process, an essential part of analytical quality assurance, can be described as the set of tests used to establish and document performance characteristics of a method. The performance characteristics of a method are experimentally derived values for the fundamental parameters of importance in assessing the suitability of the method (Horwitz 1988, 1995 Thompson and Wood 1993, 1995 Eurachem 1996 FAO 1998 US EPA 1995 US FDA 1993a). These parameters include ... 

EXPERIMENTAL The sampling and analytical method employed in determining the various solvent vapor concentrations in air are described in detail by White etal (A)and NIOSH (2), Four Bendix National Environmental Instruments Model BDX 30 Personal Samplers were used daily (one in each laboratory) with large size charcoal tubes (SKC cat no. 226-09-100) which contained two sections of activated charcoal per tube (a 400 milligram section followed by a 200 mg backup section to indicate when "breakthrough" of the main section has occurred). The sampling pumps were operated at a rate of one liter per minute and were calibrated by means of an Environmental Compliance Corporation Model 302 Universal Pump Calibrator (a device that generates a thin film of soap which is carefully timed as it traverses a very... 

As mentioned above, it is very difficult, for experimental reasons, to measure the relaxation modulus or the creep compliance at times below 1 s. In this time scale region, dynamic mechanical viscoelastic functions are widely employed (5,6). However, in these methods the measured forces and displacements are not simply related to the stress and strain in the samples. Moreover, in the case of dynamic experiments, inertial effects are frequently important, and this fact must be taken into account in the theoretical methods developed to calculate complex viscoelastic functions from experimental results. 

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