Single Strength Test Research Articles

Generalization of Muscle Strength Capacities as Assessed From Different Variables, Tests, and Muscle Groups.

Cuk, I, Prebeg, G, Sreckovic, S, Mirkov, DM, and Jaric, S. Generalization of muscle strength capacities as assessed from different variables, tests, and muscle groups. J Strength Cond Res 31(2): 305-312, 2017-The muscle strength capacities to exert force under various movement conditions have been indiscriminately assessed from various strength tests and variables applied on different muscles. We tested the hypotheses that the distinctive strength capacities would be revealed (H1) through different strength tests, and (H2) through different strength variables. Alternatively, (H3) all strength variables independent of the selected test could depict the same strength capacity of the tested muscle. Sixty subjects performed both the standard strength test and the test of alternating contractions of 6 pairs of antagonistic muscles acting in different leg and arm joints. The dependent variables obtained from each test and muscle were the maximum isometric force and the rate of force development. A confirmatory principle component analysis set to 2 factors explained 31.9% of the total variance. The factor loadings discerned between the tested arm and leg muscles, but not between the strength tests and variables. An exploratory analysis applied on the same data revealed 6 factors that explained 60.1% of the total variance. Again, the individual factors were mainly loaded by different tests and variables obtained from the same pair of antagonistic muscles. Therefore, a comprehensive assessment of the muscle strength capacity of the tested individual should be based on a single strength test and variable obtained from a number of different muscles, than on a single muscle tested through different tests and variables. The selected muscles should act in different limbs and joints, while the maximum isometric force should be the variable of choice.

Combustion chemical vapor deposition (CCVD) of LaPO 4 monazite and beta-alumina on alumina fibers for ceramic matrix composites

This research used the low cost, open atmosphere combustion chemical vapor deposition (CCVD SM) method to efficiently deposit protective coatings onto alumina fibers (3M Nextel™ 610) for use in ceramic matrix composites (CMCs). La-monazite (LaPO 4) and beta-alumina were the primary candidate debonding coating materials investigated. The coated fibers provide thermochemical stability, as well as desired debonding/sliding interface characteristics to the CMC. Dense and uniform La-phosphate coatings were obtained at deposition temperatures as low as 900–1000°C with minimal degradation of fibers. However, all of the β-alumina phases required high deposition temperatures and, thus, could not be applied onto the Nextel™ 610 alumina fibers. The fibers appeared to have complete and relatively uniform coatings around individual filaments when 420 and 1260 filament tows were coated via the CCVD process. Fibers up to 3 feet long were fed through the deposition flame in the laboratory of MicroCoating Technologies (MCT). TEM analyses performed at Wright-Patterson AFB on the CCVD coated fibers showed a 10–30 nm thick La-rich layer at the fiber/coating interface, and a layer of columnar monazite 0.1–1 μm thick covered with sooty carbon of <50 nm thick on the outside. A single strength test on CCVD coated fibers performed by 3M showed that the strength value fell in the higher end of data from other CVD coated samples.

19—THE STRENGTH OF FIBRE BUNDLES AND TOPS

Results are given of strength tests on fibre bundles and wool tops with greater-than-zero jaw-separation distances. Strength tests on large bundles of man-made fibres are highly repeatable, while with constant jaw-separation the strength of comb-sorter wool fibre bundles from a top decreases per unit area of cross-section as fibre length (and fibre diameter) decrease. For both man-made fibre and wool tops, there is a linear relationship between log breaking load in lb/g, based on the weight of the fibres cut from between the jaws after breaking, and the distance apart of the jaws. From this relationship, a measure of the intrinsic strength of the fibres and the mean fibre length of wool tops can be obtained. The relationship between top strength and mean fibre length was studied on a group of 30 Merino tops, similar in fibre diameter, but varying in mean fibre length. From a single strength test with a jaw-separation of 5·1 cm (2·0 in.), the mean fibre length of the top could be predicted with a standard ...