Beam Test

The UV dose data from bench-scale collimated beam tests for UV disinfection was first reported by Qualls and Johnson (23). Their original apparatus consisted of low-pressure UV lamps housed in a cardboard box with a 5.08 cm diameter, 72 cm long tube extending from a cut-out hole in the middle of the lamp arc length (20). 

The UV design has been somewhat of an art form based on utility and budget. While the germicidal UV dose can be estimated in a collimated beam system, the reported dose-response relationships, however, vary considerably. Therefore, a careful design of the system and analysis of data for full-scale UV disinfection become essential. 

As one can find from Eqs. (12) and (19), the collimated beam test is to measure t, and number of pathogens left in the suspensions. Thus, a proper experimental determination of these parameters is very important. According to Eq. (12), the measurable items in the test include exposure time, distance from lamp centerline to suspension surface, depth of the suspension, and number of pathogens. The main procedure sequence is (3)  

Place a known volume from the sample in a container and stir it by nsing magnetic stirrer. 

Measnre the water depth in the above container so that the depth of the Petri dish can be determined. 

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Fig. 2. Illustrations of forces to which adhesive bonds are subjected, (a) A standard lap shear specimen where the black area shows the adhesive. The adherends are usually 25 mm wide and the lap area is 312.5 mm. The arrows show the direction of the normal apphcation of load, (b) A peel test where the loading configuration, shown by the arrows, is for a 180° peel test, (c) A double cantilever beam test specimen used in the evaluation of the resistance to crack propagation of an adhesive. The normal application of load is shown by the arrows. This load is appHed by a tensile testing machine or other...

Fracture mechanics (qv) tests are typically used for stmctural adhesives. Thus, tests such as the double cantilever beam test (Fig. 2c), in which two thick adherends joined by an adhesive are broken by cleavage, provide information relating to stmctural flaws. Results can be reported in a number of ways. The most typical uses a quantity known as the strain energy release rate, given in energy per unit area. 

These effects have been found by Creton et al. [79] who laminated sheets of incompatible polymers, PMMA and PPO, and studied the adhesion using a double cantilever beam test to evaluate fracture toughness Fc. For the original laminate Fc was only 2 J/m, but when interface reinforced with increasing amounts of a symmetrical P.M.M.A.-P.S. diblock copolymer of high degree of polymerisation (A > A e), the fracture toughness increased to around 170 J/m, and then fell to a steady value of 70 J/m (Fig. 9). 

Another test used to determine the shear modulus and shear strength of a composite material is the sandwich cross-beam test due to Shockey and described by Waddoups [2-17]. The composite lamina... 

Elevator beams tested for safe working loading ... 

Fig. 3.33 Bent-beam test results in aerated distilled water. These specimens were exposed to the environment at a stress of 70% of yield (after Setterlund, Materials Protection, 4 No. 12,...

Further evidence of the relative resistance of maraging steel is reproduced in Fig. 3.33 from Reference 24. Maraging steel is shown to be superior to a die steel and low alloy steel (both unidentified) in bent beam tests stressed at 75% of the yield strength in distilled water. Also shown is the beneficial effect in smooth surface tests of cold rolling. Shot peening has a similar beneficial effect . 

We test the impact resistance of polymer plaques using the configuration shown in Fig. 8.8. We subject circular injection molded plaques to the shock of a falling weight with a hemispherical impacter. This test is also known as the Dart Drop Test . Samples can fail in a brittle or a ductile manner. Brittle samples often shatter. Ductile samples can split or a small disk may be punched out of their center. This test provides results that are analogous to those obtained from un-notched impact beam testing. 

The exposed HS-MOTSS copolymer films were dip-developed in solvent followed by baking at 50-80 °C in vacuum for about 30 min. E-beam dose matrice images were developed in chlorobenzene for 30 sec ion beam test exposures were developed in methyl isobutyl ketone for 30 sec. The thicknesses of the films were measured with a Nanospec/AFT microarea film thickness measuring system. 

Hashemi, S., Kinloch, A.J. and Williams, J.G. (1989). Corrections needed in double-cantilever beam tests for assessing the interlaminar failure of fiber-composites. J. Mater. Sci. Lett. 8, 125-129. 

Fig. 5.9. Load-displacement records of double-cantilever-beam tests on E-glass fiber-vinyl ester matrix composites, (a) 0.4 wt% epoxy silane (b) 0.01 wt% methacrylate silane (c) 0.4 wt% methacrylate silane (d) 1.0 wt% methacrylate silane. After Suzuki et al. (1993).

Bj) Beam Test, used for pressure-actuated fuzes, consists of placing the fuze under the free end of a steel beam that is hinged on the opposite end. A known load is then applied remotely to the free end of the beam. The load is increased un til the fuze is actuated (p IIB-41 of Ref 39)... 

Short beam tests provided information on the apparent interlaminar shear strength (ILSS) of laminates made with bare and sized E-glass fibers. In all cases, the specimens failed in shear at or near the midplane, allowing comparisons between fiber types. The ILSS, SD, and number of specimens tested are given in Table 5. 

The problem of definition of modulus applies to all tests. However there is a second problem which applies to those tests where the state of stress (or strain) is not uniform across the material cross-section during the test (i.e. to all beam tests and all torsion tests - except those for thin walled cylinders). In the derivation of the equations to determine moduli it is assumed that the relation between stress and strain is the same everywhere, this is no longer true for a non-linear material. In the beam test one half of the beam is in tension and one half in compression with maximum strains on the surfaces, so that there will be different relations between stress and strain depending on the distance from the neutral plane. For the torsion experiments the strain is zero at the centre of the specimen and increases toward the outside, thus there will be different torque-shear modulus relations for each thin cylindrical shell. Unless the precise variation of all the elastic constants with strain is known it will not be possible to obtain reliable values from beam tests or torsion tests (except for thin walled cylinders). 

A series of pulsed electron beam tests were conducted on dextrinated and RD-1333 Pb azide pellets by Avrami et al (Ref 232), From the limited data in Table 14 it can be seen that sample ambient pressure, sample thickness and type of Pb azide are all important factors in the sensitivity of initiation by pulsed electron beam The question arises as to what mechanism can explain the observed pressure, thickness and type of Pb azide dependence. A purely thermal initiation mechanism or a compressive shock initiation resulting from nearly instantaneous energy deposition can account for some of the observations but not all... 

The resonant beam test technique forms the basis of the ASTM Standard E756-83 for measuring the viscoelastic properties of damping materials. Fundamentally, the beam test requires that the resonant frequencies of a metal-beam, mounted in cantilever fashion, be determined as a function of temperature and frequency the beam is then coated with a polymer and the resonant frequencies and corresponding modal damping of the composite beam are determined as a function of temperature and frequency. From these two data sets, the vibration damping properties of the polymer can be evaluated. The ASTM Standard provides the necessary equations to obtain the complex modulus data from the collected test data and also provides guidelines for the proper choice of the specimens (1.21. The principal difference between the beam test and the other methods used here is that the beam test calculates the material properties from the test results on the metal beam and the composite beam whereas the... 

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