Supporting Specimens

In a few special cases, the standard spool-type specimen holder is not applicable and a suitable special test method must be devised to apply to the corrosion conditions being studied. 

For conducting tests in pipe lines of 75-mm (3-in) diameter or larger, a spool holder as shown in Fig. 25-19, which employs the same disk-type specimens used on the standard spool holder, has been used. This frame is so designed that it may be placed in a pipe line in any position without permitting the disk specimens to touch the wall of the pipe. As with the strip-type holder, this assembly does not materially interfere with the fluid through the pipe and permits the study of corrosion effects prevailing in the pipe line. 

Another way to study corrosion in pipe lines is to install in the line short sections of pipe of the materials to be tested. These test sections should be insulated from each other and from the rest of the piping 

25-19 Spool -type specimen holder for use in 3-in-diameter or larger pipe. (Mantell, ed.. Engineering Materials Handbook, McGraw-Hill, New Yoi, 1958.) 

Method for fastening specimen to structural member or shaft 

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Method of Supporting Specimens The supporting device and container should not be affected by or cause contamination of the test solution. The method of supporting specimens will vary with the apparatus used for conducting the test out should be designed to insulate the specimens from each other physically and electrically and to insulate the specimens from any metric container or supporting device used with the apparatus. 

Significantly, a flexural specimen is not in a state of uniform stress. When a simply supported specimen is loaded, the side of the material opposite the loading undergoes the greatest tensile loading. The side of the material being loaded experiences compressive stress (Fig. 2-16). These stresses decrease linearly toward the center of the sample. Theoretically the center is a plane, called the neutral axis, experiences no stress. 

The experimental arrangement for the Porter experiments is shown in Figure 1.10. A small helium-neon laser illuminates an object, which is a 3-mm diameter copper grid of the type commonly used for supporting specimens for transmission electron microscopy. The spacing d between grid bars is 125 /tm. 

Controlled atmosphere electron microscopy was used to directly follow the formation of carbonaceous deposits on supported ruthenium particles during reaction with acetylene (ref. 73). Under these conditions the major type of deposit was filamentous carbon, and its growth characteristics were found to depend on the nature of the support, specimen pre-treatment conditions, and the reaction temperature. When the reaction was performed on a graphite support the filaments were produced by the... 

A variation of the torsion pendulum, torsional braid analysis (TBA), utilizes a supported specimen so that the dynamic mechanical properties of a sample can be monitored in the liquid as well as the solid states (1, 2). An inert multifilamented glass braid is impregnated with the sample (usually in its liquid state or in solution). The observed dynamic mechanical properties are relative due to the composite nature and complex geometry of the specimen. 

Figure 11. A comparison of torsion pendulum data obtained using a film /" , shear modulus vs. T , log decrement vs. T] and TBA data obtained using a supported specimen [ 0, relative rigidity vs. T O, log decrement vs. T].

The USACHPPM is responsible for providing bioassay support. Specimens for bioassay are collected at medical treatment facilities by occupational health professionals and sent to USACHPPM for analysis and dose assessments. 

Figure 9. Progression of impact damage with velocity in (a) fully supported and (b) partially supported specimens. The vertical arrow indicates a case of increasing impact velocity.

The overall impact damage of the oxide/oxide composite was found to be greater in partially supported specimens than for fully supported ones. 

For fully supported specimens, frontal contact stresses together with cone cracking played a major role in generating composite damage whereas, for partially supported ones, both frontal contact and backside flexure stresses were combined sources of damage generation. 

Standardized methods cover tests of rigid self-supporting specimens, flexible films, and expanded materials with a bulk density not lower than 100 kg/m. Types of specimens laid down by the standard ISO/DIS 4589-1983 are listed in Table 3.5. Specimens for other standards are essentially identical to these except for ASTM D 2863-1977 in which specimens I, II and III are not involved instead, the oxygen index of rigid solids is determined on specimen IV, while specimens with cross section of 12.5 mm square are used for testing plastic foams. Testing flexible films is the same for all standards. 

The test specimen, disk or plaque, is placed in a clamp such that its upper and lower surfaces are securely supported. Specimen thickness should be between 0.127 and 12.7 mm (0.005 and 0.5 in.). A punch-type shear tool with a 25.4 mm (1 in.) diameter is bolted to the specimen through a hole drilled in the center and a load is applied to the... 

Figure 11.9 Relationship of support, specimen, and striking edge to each other in Charpy impact test (ISO 179-1 1998).

ASTM G 39, Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens— This describes methods for design, preparation, and use of bent-beam stress-corrosion specimens. This standard covers apparatus for supporting specimens, basic design of a specimen, stress calculations, test conditions, exposure, and inspection techniques. 

Figure 3-77. A schematic of an Izod impact tester. A free-swinging pendulum strikes a vertically supported specimen held in a clamp a notched specimen is located so that its notch is level with the top of the clamp and is facing the pendulum, per ASTM D 256.

Transition metals and Ni-Cu binary alloys were tested. The metals of 99.9%Cr, 99.9%Mn, 99.9%Fe, 99.96%Co, 99.97%Ni, and 99.5%Cu (in mass%) were chosen from the fourth periodic transition-metal elements, and both 99.98%Ag and 99.98%Pt were also tested. The binary alloys of Ni-Cu have differing contents of Cu 1.0, 2.0, 2.9, 4.9, 10.0, 18.3, 49.5, and 69.6 (in mass%). Coupon specimens were cut from sheets or plates, and a small hole of 2mm diameter was drilled in them for support. Specimens of Cr, Mn, and Pt were supported directly by a spot-welded Pt hook. For the binary alloys, button-ingots were made in an arc-melting fimiace rmder an inert argon atmosphere. Coupon specimens were cut from the hot-rolled plates (5 mm thickness) with a solution-heat treatment at 1100°C in air. All of the specimens were... 

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