Composites Testing

Recommendation When all measurements were recorded by hand, operators and engineers could use their judgment concerning their validity. Now with most acqmred automatically in enormous numbers, the measurements need to be examined automatically. The goal continues to be to detect correctly the presence or absence of gross errors and isolate which measurements contain those errors. Each of the tests has limitations. The hterature indicates that the measurement test or a composite test where measurements are sequentially added to the measurement set are the most powerful, but their success is limited. If automatic analysis is required, the composite measurement test is the most direct to isolation-specific measurements with gross error. 

Table 24.1 Properties of mouldings prepared from urea-formaldehyde and melamine-formaldehyde mouldings compositions (Testing according to BS 2782)...

Liquid type and composition Test condition Category of attack Mass change (g) Change in diameter cm ... 

Test name Ref. Usual solution composition Test procedure Quantitative measure Potential range (V vs. S.H.E.) Species selectively attacked... 

FIGURE 4.10 Mobile phase selection by microcircular technique, a. Sample of known composition A = nonpolar compound A1 = n-hexane A2 = acetone A3 = n-hexane-acetone, 60-1-40, v/v B = polar compound B1 = methanol B2 = water B3 = methanol-water, 70-1-30, v/v. b. Sample of unknown composition testing with solvents of different Snyder s groups and binary solvent mixture. 

Consumer Safety Regulations are based on test procedures which are scientifically unsound and that they contradict the essentials of composites testing and hazard based fire tests, large scale hazard based tests involving the newer types of combustion modified PU foams with suitable fabrics have shown... 

Typical tension stress-strain curves of baseline and irradiated unidirectional T300/934 composites tested in [0] and [90] orientations at three different temperatures (121 are shown in Figures 11 and 12. Irradiation had essentially no effect on the fiber-dominated tensile modulus of the [0] specimen and caused only a small (10-15%) reduction in strength at the low and elevated temperatures. For the matrix-dominated [90] laminates, irradiation caused a very substantial decrease in strength at three test temperatures (-38% at -157°C, -26% R.T., -13% 121°C). Irradiation increased the modulus at -157°C and R.T. (10 - 15%), but lowered it at 121°C (-15%). These results are consistent with results obtained on the neat resin specimens discussed above. 

Goda, K., Park, J. M. and Netravali, A. N., A new theory to obtain weibull fibre strength parameters from a single-fibre composite test, J. Mater. Sci., 30, 2722 (1995). 

Drzal, L. T., Rich, M. J. and Ragland, W., Adhesion between fiber and matrix - its effect on composite test results, presentation given at the 42nd Annual Conference, Composites Institute, 2-6, February, 1987, Preprint, Session 7-A/l. 

Bulk physical property tests, such as density and heating value, as well as some compositional tests, such as the Orsat analysis and the mercuric nitrate method for the determination of unsaturation, are still used. However, the choice of a particular test is dictated by (1) the requirements of the legislation, (2) the properties of the gas under study, and (3) the selection by the analyst of a suitable suite of tests to meet the various requirements. For example, judgment by the analyst is necessary whether or not a test that is applied to liquefied petroleum gas is suitable for process gas or natural gas insofar as inference from the nonhydrocarbon constituents will be minimal. 

Andersons, J. and Tamuzs, V. (1993). Fiber and interface strength distribution studies with the single fiber composite test. Composites Sei. Technol. 48, 57-63. 

Netravali, A.N., Hcnstenburg, R.B., Phoenix, S.L. and Schwartz, P. (1989a). Interfacial shear strength studies using the single filament composite test, part I Experiments on graphite fibers in epoxy. Polym. Composites 10, 226-241. 

Netravali, A.N., Topoleski, L.T.T., Sachse, W.H. and Phoenix, S.L. (1989c). An acoustic emission technique for measuring fiber fragment length distributions in single fiber composite test. Composites Sci. Technol. 35, 13-29. 

Sample Preparation. The sample series was prepared by varying the ratio of Epon 828 to the methylene dlaniline (MDA) curing agent. The compositions tested contained 0%, 23.1%, 50.0% and 100% excess MDA over the stoichiometric amount. The MDA and diepoxide were heated to 100°C and mixed. The mixture was cast onto one side of a sheet of aluminum 5.5 cm. x 24.5 cm. x 5 mils, which had first been wiped with acetone to degrease the bonding surface. The final coating thickness was controlled at approximately 60 mils. 

Sodium-rich glass compositions tested in single-pass flow-through (SPFT) apparatus at Pacific Northwest National Laboratory support the low-activity waste (LAW) glass disposal... 

The degree of bonding analysis has been verified for both compression molding and online consolidation of thermoplastic composites. In these studies, composite test specimens were consolidated under controlled processing conditions. The most common types of tests performed to measure the interply bond strength were the interlaminar (short beam) shear test [21,25] or the lap shear test [12,21,26]. 

TABLE 2. Hardened Dental Composition Testing Results Using Step 1 Product as Hybrid Monomer... 

The effect of silanes on the bond strength of two epoxide adhesives to glass is shown in Table 13. The test mode was that of Sandwich Butt Tensile in which a glass disc was bonded between two aluminium specimens in the form of a sandwich, and the resulting composite specimen broken on an Instron Universal Test Machine. Clearly in such a composite test specimen, alignment is important and there are many potential sites and modes of failure. 

Because foodstuffs themselves are difficult to analyse and have a variable composition, testing packaging materials for migration almost invariably uses model foods, known as food simulants , which are designed to mimic the main classes of foodstuffs. There are some minor differences in detail between EU and US-FDA requirements but the essential elements are listed in Table 9.3. 

In the lab mixer 20 batches of a composite rocket propellant were mixed under identical conditions, all of them having the same composition. Test strands were taken out of the obtained propellant and their burning rates were measured at 70 bar of pressure. The burning rate average is X=8.5 mm/s, and the calculated variance is a2=0.30. What number of strands has the burning rate ... 

Lewis, E. N., Strachan, D. and Kidder, L. H. (2004) High Volume On Line Spectroscopic Composition Testing of Manufactured Pharmaceutical Dosage Units, US Patent Application 6 690 464. 

The special needs of the space program motivated the search for composite materials for other reasons also. For example, during tests of the first Atlas ICBM (intercontinental ballistic missile), engineers were concerned that the rocket s metallic components would not survive the missile s reentry into the atmosphere they feared it would melt down because of the intense heat to which it was exposed. By the late 1950s, therefore, aerospace researchers had begun to look for satisfactory substitutes for metal alloys for such applications. With that research, the modern held of composite design was horn. One of the first composites tested consisted of pieces of glass embedded in melamine, purported to be the first composite material developed for aerospace applications. 

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