Tap test

Today the coin-tap test is a widely used technique on wind turbine rotor blades for inspection of thin GFRP laminates for disbonded and delaminated areas. However, since the sensitivity of this technique depends not only on the operator but also on the thickness of the inspected component, the coin-tap testing technique is most sensitive to defects positioned near the surface of the laminate. Therefore, there has been an increasing demand for alternative non-destmctive testing techniques which is less operator dependent and also more sensitive to delaminations and disbonded areas situated beyond thicker GFRP-laminates. 

Other classification techniques have been developed which provide some insight on fiber lengths, typically the Ro-Tap test, the Suter-Webb Comb, and the Wash test. 

Of historical interest may be the use of a half dollar coin (the lighter weight 250 not as efficient). During the early 1940s the coin tap test was used very successfully in evaluating the performances of plastics, particularly RP primary aircraft structures. With a good ear (human hearing ear) there was (and is) a definite different sound between a satisfactory and unsatisfactory RP product. The unsatisfactory product would contain voids, delaminations, defects in fiber distribution, etc. In... 

Motor ability tests focus on measures associated with motor control. The most common examples of motor tasks are finger tapping tests, tracking tests, and hand steadiness tests. 

The Foot Tap test was developed as an indication of CNS activity, in that a compound must penetrate the CNS to be active. In the test, a peptidic NK] receptor agonist, GR-73632 is administered by i.c.v. injection through a hole in the skull into the ventricles of the brain to induce the foot-tapping behavior. Once again, aprepitant (1) proved to have the longest duration of action by virtue of its lowest ID50 value at 24 h postdose, as shown in Table 4.8... 

The success of the tap test depends on the skill and experience of the operator, the background noise level, and the type of structure. Some improvement in the tap test can be achieved by using a solenoid-operated hammer and a microphone pickup. The resulting electric signals can be analyzed on the basis of amplitude and frequency. However, the tap test, in its most successful mode, measures only the qualitative characteristics of the joint. It tells whether adhesive is in the joint or not, providing an acoustical path from substrate to substrate or it tells if the adhesive is undercured or filled with air, thereby causing a mechanically damped path for the acoustical signal. The tap test provides no quantitative information and no information about the presence and/or nature of a weak boundary layer. 

Mechanical compressibility in compression tests is, at least partly, a result of the collapse of an initial open bed structure (supported by cohesive interparticle forces or interparticle liquid bridges), which is totally and irreversibly destroyed. In the case of vibrational tapping tests, the openness of the bed structure can be recovered at least to some extent. Thus, different mechanisms yield different tendencies in the compressibility measured by tapping and mechanical compressibility. 

Screen Analysis of the Substrate. The milled cellulose was screen analyzed in a Ro-Tap Testing Sieve Shaker (The W. S. Tyler Company, Cleveland, Ohio) using a series of 40, 60, 100, 120, 170, 200, and 270 mesh U.S. Standard Screens sifting for 45 min. plus an additional 5 min. after the first weight to check the reproducibility of weights of the screened fractions. Both the weights checked very well. The same procedure was followed in the case of SF, SF-H, SF-HM, SF-MH, and Sweco 70 samples, all of which were subsequently tested. Summary of screen analyses reports is presented in Table II and Figure 9. 

In a placebo-controlled crossover study in 24 patients with Parkinson s disease a single dose of entaeapone 200 mg or 400 mg given 30 minutes before a subcutaneous injeetion of apomorphine had no effeet on the phar-maeokineties of apomorphine. In addition, entaeapone had no effeet on measures of apomorphine effieaey (tapping test and ineidenee of dyskinesias). ... 

Chitin and Chitosan. Chitin through the courtesy of Kypro Co., sifting to remove fines and extraneous non-shell flakes, the remaining material was ground in a Thomas Wiley laboratory mill (Model 4, A. H. Thomas Co., Philadelphia, FA) to pass a 2.00 mm screen. Using a Ro Tap Testing Sieve Shaker (Model B, W. S. Tyler, Inc., Mentor, OH), three fractions of each material were collected <1.00-0.50 mm <0.50-0.25 mm and <0.25 mm. 

Tap testing coin tapping on a laminate structure is not recommended, but it will detect near-surface internal damage if such damage is of sufficient size. 

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