Experimental load analysis

A key problem in experimental load analysis is the translation of the data yielded from the measurement system (as represented by the load histories in Figure 4.21) into an... 

Chen WH, Lee SS. Numerical and experimental failure analysis of composite laminates with bolted joints under bending loads. J Compos Mater 1995 29(1) 15—36. 

The following sections review laboratory NDE, microscopy, and experimental stress analysis methods, which the engineer can use to obtain information about the presence and severity of flaws developed by test or parts when they are subjected to sustain mechanical loading. 

The greatest uncertainty of a design is often whether it will withstand mechanical loads and displacements. Examining critical areas of high stress or strain is most precisely quantified using experimental stress analysis methods. 

The manner in which the laminate design is approached can be expressed in flow-chart form as in Figure 7-59. There, some initial laminate is arbitrarily selected to start the procedure. Then, the laminate load-deflection behavior is evaluated by use of the laminate strength analysis procedure described in Section 4.5. That evaluation is theoretical in nature. The next step is to evaluate the laminate fatigue life, and that evaluation can only be done experimentally, although progress is... 

We have developed a compact photocatalytic reactor [1], which enables efficient decomposition of organic carbons in a gas or a liquid phase, incorporating a flexible and light-dispersive wire-net coated with titanium dioxide. Ethylene was selected as a model compound which would rot plants in sealed space when emitted. Effects of the titanium dioxide loading, the ethylene concentration, and the humidity were examined in batches. Kinetic analysis elucidated that the surface reaction of adsorbed ethylene could be regarded as a controlling step under the experimental conditions studied, assuming the competitive adsorption of ethylene and water molecules on the same active site. 

Experimentally the resolution in GPC 1 was increased by the long column lengths and low flow rate but degraded somewhat by the high sample loadings. The high flow rate in GPC 2 was only necessary because in these exploratory studies many different runs had to be performed and necessitated short analysis times. 

For the analysis of nonvolatile compounds, on-line coupled microcolumn SEC-PyGC has been described [979]. Alternatively, on-line p,SEC coupled to a conventional-size LC system can be used for separation and quantitative determination of compounds, in which volatility may not allow analysis via capillary GC [976]. An automated SEC-gradient HPLC flow system for polymer analysis has been developed [980]. The high sample loading capacity available in SEC makes it an attractive technique for intermediate sample cleanup [981] prior to a more sensitive RPLC technique. Hence, this intermediate step is especially interesting for experimental purposes whenever polymer matrix interference cannot be separated from the peak of interest. Coupling of SEC to RPLC is expected to benefit from the miniaturised approach in the first dimension (no broadening). Development of the first separation step in SEC-HPLC is usually quite short, unless problems are encountered with sample/column compatibility. 

In such an analysis, the first spectral component (or factor) represents the most common elements of all the experimental spectra used. The second component represents the major variance from that average. Each successive component then becomes less significant, eventually being just noise contributions. The components are constructed to be orthogonal, but their orientation is arbitrary and is dependent on the set of spectra used, since the first component is the average. The original spectra, (k, can be represented as a linear combination of factors, j, and loadings a,j as... 

Literature data for the suspension polymerization of styrene was selected for the analysi. The data, shown in Table I, Includes conversion, number and weight average molecular weights and initiator loadings (14). The empirical models selected to describe the rate and the instantaneous properties are summarized in Table II. In every case the models were shown to be adequate within the limits of the reported experimental error. The experimental and calculated Instantaneous values are summarized in Figures (1) and (2). The rate constant for the thermal decomposition of benzoyl peroxide was taken as In kd 36.68 137.48/RT kJ/(gmol) (11). 

Of particular importance with the use of LC-NMR as an experimental technique is that it is suited for only a limited number of applications in reference to structure elucidation. As will be discussed in greater detail, the sensitivity issues that arise between the amount of compound one is able to load onto a particular chromatographic stationary phase, and hence elute into the flow-cell of an LC-NMR probe, limit what type of structural analysis that can be performed. It is this author s current opinion that most complete structure elucidations of unknown molecular entities are not amenable to LC-NMR. In these... 

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