Strength testing

Biaxial flexure is another approach that uses a bending configuration. In this test, the specimen is supported on a ring or three balls and the load is applied in the center of the opposite face. The specimens for this test are often circular plates but rectangular plates can also be utilized. 

In all the above testing approaches, it is critical for the details of the testing procedure to be reported. As shown later, the strengths of ceramics are dependent on the loading geometry and specimen dimensions. It is particularly important to understand these effects, when comparing strength data from various sources. 

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Strecker reaction Strecker synthesis Strengthening agent Strength testing Strepavidin Strep, pyogenes Cruz Strep tase... 

Although the USP defines the knot-pull tensile strength test in terms of a surgeon s knot, most surgeons use a variety of other knots depending on... 

The hot mixes are designed by using a standard laboratory compaction procedure to develop a composition reflecting estabUshed criteria for volume percent air voids, total volume percent voids between aggregate particles, flow and stabdity, or compressive strength. Tests such as the Marshall, Unconfined Compression, Hubbard-Field, Triaxial Procedure, or the Hveem stabdometer method are used (109). 

Mechanical Properties and Stability at Elevated Temperature. One increasingly important characteristic of carbon fibers is their excellent performance at elevated temperatures. Strength tested in an inert environment remains constant or slightly increases to temperatures exceeding 2500°C. Amoco s high modulus pitch carbon fiber P-50 maintains approximately 80% of room temperature modulus at temperatures up to 1500°C, then decreases more rapidly to 30% at 2800°C (64). The rapid decrease in modulus is a result of increased atomic mobiHty, increa sing fiber plasticity. 

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

R. Byron Pipes and B. W. Cole, On the Off-Axis Strength Test for Anisotropic Materials, Journal of Composite Materials, April 1973, pp. 246-256. 

In the shear bond strength test, the cement slurry is allowed to cure in the annulus of two concentric steel cylinders. After curing the force to break the bond between the set cement and one of the cylinders (usually the inner one)... 

The efficiency of transformer oils as dielectrics is measured by electric strength tests. These give an indication of the voltage at which, under the test conditions, the oil will break down. Various national standards exist that all measure the same basic property of the oil. There is an international specification, lEC 296/1982, which may be quoted by equipment manufacturers in their oil recommendations. 

Testing should include a dielectric strength test to confirm the oil s insulation capability and an acidity test, which indicates oil oxidation. While acid formation does not usually develop until the oil has been in service for some time when it does occur the process can be rapid. If acidity is below 0.5 mg KOH/g no action would seem necessary. Between 0.5 and 1 mg KOH/g, increased care and testing is essential. Above 1 the oil should be removed and either reconditioned or discarded. Before the unit is filled with a fresh charge of oil it should be flushed. 

Each of the multilayered materials of Table II, in pouch form, met the retortability requirements. Examination of the pouches after this test showed that no delamination occurred among the layers. However, microscopic examination of specimens used for bond strength tests showed that adhesive failure rather than cohesive failure occurred be-... 

Imide precursor, 317 Imide-terminated telechelics, 457 Impact strength tests, 243 Impet, 21... 

TDI isomers, 210 Tear strength tests, 242-243 TEDA. See Triethylene diamine (TEDA) Telechelic oligomers, 456, 457 copolymerization of, 453-454 Telechelics, from polybutadiene, 456-459 TEM technique, 163-164 Temperature, polyamide shear modulus and, 138. See also /3-transition temperature (7)>) Brill temperature Deblocking temperatures //-transition temperature (Ty) Glass transition temperature (7) ) Heat deflection temperature (HDT) Heat distortion temperature (HDT) High-temperature entries Low-temperature entries Melting temperature (Fm) Modulu s - temperature relationship Thermal entries Tensile strength, 3, 242 TEOS. See Tetraethoxysilane (TEOS)... 

In addition to the strength tests already mentioned, there are other tests which can be applied and which at first sight give an indication of strength. These include hardness and fatigue tests. In reality all of these tests measure different physical attributes of the material and for a truly comprehensive picture of the behaviour of any material, results from all of these types of test should be known. 

Williams, P. D. Smith, D. C. (1971). Measurement of the tensile strength of dental restorative materials by use of a diametral compressive strength test. Journal of Dental Research, 50, 436-42. 

The diametral compressive strength has been used to estimate the tensile strength of certain AB cements (Smith, 1968). In this test, the load is applied diametrically across a cylinder of cement. Theoretical consideration of the test geometry shows that for a perfectly brittle material the failure that occurs is tensile in character. The difficulty in applying this test to AB cements is that they are not sufficiently brittle for this to hold true. In particular, the zinc polycarboxylate and glass-ionomer cements show sufficient plastic character to make the relationship between diametral compressive and tensile strength vary between AB cements of different types like the compressive strength test, this test is valid only as a means of comparison between similar materials (Darvell, 1990). 

Table 17 Summary of tensile strength test results for Sample 4 ...

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