Destruction tester

Taguchi and Tanaka have described a similar method to measure the mechanical strength of microcapsules [46]. The instrument, a destruction tester (Aikoh Co. Ltd., Model 1307), which is used for such studies is shown in Figure 5.16. 

Khrushchev (1957) considers that the need to measure the force T has not been sufficiently well substantiated, nor has a sufficiently precise and easy in service hardness tester been developed yet for determinations of this type. However, he appreciates the usefulness of scratch hardness tests, especially at low loads, as a non-destructive technique. He recommends these methods as very useful for hardness determination of metallic layers or of materials exposed to abrasive wear under operating conditions (plastics, organic coatings, such as varnishes and paints, etc.). Scratch methods are especially important in tests of anisotropic materials where a change in scratch width is the measure of anisotropy. In static indentation methods, the indentations obtained in anisotropic materials are misformed, varying... 

The solid-like properties may be measured by non-destructive dynamic rheology analysis or by destructive methods using a Penetrometer, Jelly Tester, Instron instruments, or other types of texture analyzers. The latter methods are the most useful due to their simplicity and speed. Texture analysis of whippable emulsion must always be compared with the amount of air incorporated into the foam, which is known as percentage overrun and is calculated as follows ... 

Tablet hardness is a property that, when measured, destroys the sample. The destructive nature of the test, coupled with the variability of the test itself does not contribute to an incentive to test a large number of samples. Morisseau and Rhodes99 correlated the diffuse reflectance NIR spectra of tablets pressed at different pressures and subsequently tested the tablet hardness with an Erweka Hardness Tester. The tablet hardness, as predicted by the NIR method, was at least as precise as the laboratory test method. Kirsch and Drennen100 evaluated NIR as a method to determine potency and tablet hardness of Cimetidine tablets over a range of 1-20% potency and 107-kPa compaction pressure. Hardness at different potency levels was used to build calibration models using PCA/ principal component regression and a new spectral best-fit algorithm. Both methods provided acceptable predictions of tablet hardness.

Both destructive and nondestructive measurements can be done on an Instron Material Tester. In this system, the sample is loaded in a test cell, and the compression or tension force is measured when the upper part of the cell is moved over a given distance (time). Within the elastic limit of the gel, the elastic modulus E (or gel strength) is obtained from the initial slope of the nondestructive stress/strain curve additional deformation results in the breakage of the sample, giving the characteristic parameters—yield stress and breaking strain. 

In the search for a strength tester almost every joint parameter that can be determined non-destructively has been studied for a correlation with bond strength. Almost every means of probing the joint has been investigated, for example elastic waves, microwaves. 

Fig. 1. Comparison of destructive shear strength tests on laminates with the predicted strengths using a Fokker bond tester. A series of laminates is represented where the adherend thickness t varies as follows ( ), t = 0.6 mm (O), t = 0.8 mm (x), f = 1.0 mm (-h), f = 1.2 mm (A), t = 1.5 mm. To construct this standard plot, 120 specimens of Dural 2024-T3 were used 95% of all results are within the range 0.36 kg mm . (From R J Schliekelmann, Non-destructive testing of adhesively bonded joints, in Adhesion, Fundamentals and Practice, McClaren, London, 1966)...

Figure 1 shows an example of the degree of correlation that can be achieved between strengths predicted by the Fokker bond tester and those determined destructively for a bonded laminate. Figure 2 shows a similar correlation for bonded honeycomb structures. 

Non-destructive testing of adhesively-bonded structures G J CURTIS Acoustic wave techniques, resonance and pulse-echo testers... 

Hardness of peripheral regions should be tested. The impressions or indentations made by instruments such as the Barcol tester are considered destructive testing, although many materials recover fully. 

The static test can be carried out with standard tensile testers that cover the appropriate force range, optionally with a data recorder to obtain a force plot. Dynamic tests require special vibrating devices with constant loads. After the destructive test further information can be gathered from the test specimen. The nature of the break is an important indication of the quality of a bond line. There are three types of ftiilure ... 

Non-destructive tests of the material hardness of the columns were made by the hardness tester TH 130 and then converted by means of a standardised relationship to the ultimate strength in compression. The results indicated that the ultimate strength of the cast-iron varies in a rather broad range from 665 to 800 MPa. 

One of the more weird adhesion tests is the Mattox bad breath test . In this test, a person breathes on the film to condense moisture. If the film has a high residual stress, the moisture accelerates fracture propagation. When the film fails it blisters or flakes. Obviously, the uninformed individual attributes the failure to the bad breath of the tester. This test has the advantage that it can be done immediately and without equipment. If the film cannot pass this test it will probably fail in the future. The condensing breath often contaminates the film surface for further use and the test could probably be improved to be non-destructive. 

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