Testing standard test specimens

ProcGen generates a scaled 3D model of the test specimen geometry, in the form of a faceted boundary representation. This model is made available for use by other software tasks in the system. The STEP file format (the ISO standard for product data exchange) was chosen to provide future compatibility with CAD models produced externally. In particular part 204 (faceted b-rep) of this standard is used. 

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...

Film and sheeting materials test methods have been standardized by ASTM, DIN, and others. As with all materials, the test specimens must be carefiiUy prepared and conditioned. Thin-film specimens are vulnerable to nicks and tears which mar the results. Moisture and temperature can affect some materials. Common test methods are Hsted in Table 1. 

Specific Tests. Federal (United States) Motor Vehicle Safety Standard (MVSS) 302 is used to measure the burning behavior of materials used in automobile interiors. A specimen is mounted horizontally and ignited for 15 seconds. The burning rate should be below 10 cm /min. The test specimen is 35.5 X 10.1 cm by the actual thickness (up to 1.3 cm). Automakers typically impose more severe criteria than the 10 cm /min in the standard. 

Test Methodfor Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method, ASTM C423-90a, ASTM, Philadelphia, Pa., 1990. Standard Practices for Mounting Test Specimens During Sound Absorption Tests, ASTM E795-92, ASTM, Philadelphia, Pa., 1992. 

Effectiveness of these EP oils can be evaluated by a number of laboratory test units such as those shown in Figure 4. While the American Society for Testing and Materials (ASTM) procedures describe a number of standard test procedures (10), the operating conditions and test specimen materials should be chosen to simulate as nearly as possible those in an appHcation. 

Recommended Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens," specification Gl, Annual Book ofASTM Standards, American Society for Testing and Materials, Philadelphia, Pa., 1992. 

ISO/DIS 1874-2, Plastics Polyamide (PM) Moulding and Extrusion Materials, Part 2 Preparation of Test Specimens and Determination of Properties, International Standards Organization, Geneva, Switzedand, 1994. 

AATCC methods for determining water repeUency are AATCC 22 (spray test) and AATCC 70 (tumble jar dynamic absorption test). In the spray test, water is sprayed against the taut surface of the test specimen to produce a wetted pattern the size of which depends on the repeUency of the fabric. Evaluation is by comparing the pattern with a series of patterns on a standard chart. The latter method evaluates the percentage by weight of water absorbed by a sample after dynamic exposure to water for a specified period of time. 

In fastness to peroxide bleaching, ISO 10S-N02, the specimen is immersed ia a standard bleaching solution containing hydrogen peroxide (or sodium peroxide for viscose) where the composition of the bleaching Hquor is dependent on the fibers used ia the test specimen as are the pH and time of exposure (1—2 h). The objective of the test is to assess the colorfastness usiag typical bulk bleaching conditions for the fiber under test. 

Corrosion effect of forming Elongation X gauge length Standard hydropress specimen test True stress-strain curve Uniformity of characteristics... 

Probe-kolbea, m. test flask sample flask, -kom, n. assay button, -korper, m. teat body, test specimen sample. -Idffel, m. assay spoon, -machen. n. testing, assay mg. -mass, n. standard measure. 

Recommended methods for assessing the corrosivity of waters, including flowing potable waters, are described in ASTM 02688 1983. Three procedures are described in which test specimens in the form of wires, sheets or tubes are placed in pipes, tanks or other equipment. The test assembly for the first of these consists of three helical wire coils mounted in series on, and electrically insulated from, a supporting frame. The assembly must be installed so that flow is not disturbed and turbulence and high velocities, e.g. of more than 1 -53 ms , are avoided. A minimum test period of 30 days is recommended. Procedures for the other specimen forms are given in the standard. 

Laboratory tests used in the development of inhibitors can be of various types and are often associated with a particular laboratory. Thus, in one case simple test specimens, either alone or as bimetallic couples, are immersed in inhibited solutions in a relatively simple apparatus, as illustrated in Fig. 19.34. Sometimes the test may involve heat transfer, and a simple test arrangement is shown in Fig. 19.35. Tests of these types have been described in the literatureHowever, national standards also exist for this type of test approach. BSl and ASTM documents describe laboratory test procedures and in some cases provide recommended pass or fail criteria (BS 5117 Part 2 Section 2.2 1985 BS 6580 1985 ASTM 01384 1987). Laboratory testing may involve a recirculating rig test in which the intention is to assess the performance of an inhibited coolant in the simulated flow conditions of an engine cooling system. Although test procedures have been developed (BS 5177 Part 2 Section 2.3 1985 ASTM 02570 1985), problems of reproducibility and repeatability exist, and it is difficult to quote numerical pass or fail criteria. 

In many cases, even the method of conditioning prior to test will influence the ratings. For example, flexural tests run on standard conditioned specimens (50% relative humidity and 73.5°F) may rank materials differently from tests conducted on specimens which have been immersed in water or which have been heated to some elevated temperature after outdoor exposure. 

Conditioning procedures of test specimens and products are important in order to obtain reliable, comparable, and repeatable data within the same or different testing laboratories. Procedures are described in various specifications or standards such as having a standard laboratory atmosphere [50 2% relative humidity, 73.4 1.8°F (23 1°C)] with adequate air circulation around all specimens. The reason for this type or other conditioning is due to the fact the temperature and moisture content of plastics can affect different properties. 

The specimen may be a sheet of any size convenient to test, but should have uniform thickness. The test may be run at standard room temperature and humidity, or in special sets of conditions as desired. In any case, the specimens should be preconditioned to the set of conditions used. Electrodes are applied to opposite faces of the test specimen. The capacitance and dielectric loss are then measured by comparison or substitution methods in an electric bridge circuit. From these measurements and the dimensions of the specimen, dielectric constant and loss factor are computed. 

The specimen has no specified size. Specimens for this test may consist of any standard fabricated test specimen or cut/punch pieces of sheet or machined sample. Specimens are mounted outdoors on racks slanted at 45° and facing south. It is recommended that concurrent exposure be carried out in many varied climates to obtain the broadest, most representative total body of data. Sample specimens are kept indoors as controls and for comparison. Reports of weathering describe all changes noted, areas of exposure, and period of time. 

As reviewed it is important that test specimens or products be properly prepared based on available specifications and/or standards that provide controlled conditioning procedures when conducting weathering as well as all other tests. The following is one example. There are other conditions set forth to provide for testing at higher or lower levels of temperature and humidity. 

Microindentation hardness normally is measured by static penetration of the specimen with a standard indenter at a known force. After loading with a sharp indenter a residual surface impression is left on the flat test specimen. An adequate measure of the material hardness may be computed by dividing the peak contact load, P, by the projected area of impression1. The hardness, so defined, may be considered as an indicator of the irreversible deformation processes which characterize the material. The strain boundaries for plastic deformation, below the indenter are sensibly dependent, as we shall show below, on microstructural factors (crystal size and perfection, degree of crystallinity, etc). Indentation during a hardness test deforms only a small volumen element of the specimen (V 1011 nm3) (non destructive test). The rest acts as a constraint. Thus the contact stress between the indenter and the specimen is much greater than the compressive yield stress of the specimen (a factor of 3 higher). 

A number of thermal stability tests arc available, some of which have developed into national (DIN) or international industrial standards (ISO). Pigments in thermoplastic systems, for instance, are studied under heat extrusion conditions [110]. The colorant to be tested, possibly together with titanium dioxide, is dispersed in the thermoplastic, using a mixer and a granulating extruder (Sec. 1.8.3). The pigmented test pellets are then fed into a screw extruder which ejects a standardized test specimen with defined dimensions [111]. Starting at the lowest possible temperature level, the extrusion temperature is increased by intervals of 10 or 20°C between samples. 

A number of standards are available for determining these properties. They relate both to the composition and the manufacture of the basic compounds of unplasticized and plasticized PVC and of PVC plastisols and the production of the individual test specimens as well as to the performance and evaluation of the tests [29-31],... 

The property measurement methods are standardized and only allow comparisons the test specimens are produced under the best possible conditions, the deleterious factors are isolated to avoid any synergy, the duration of tests is inevitably limited, etc. In real life, this... 

A series of delamination rate tests were conducted on the Chemlok 205/220 adhesive system. The test specimen was developed from a modification of the standard (ASTM D-429) peel test. Each specimen had two one inch square bond areas on a monel substrate. 

There are a number of factors contributing to this discrepancy, such as a lack of standardization in specimen preparation, the loading method, the measurement and data reduction methods. Details of major contributors to the large data scatter are summarized for each testing method in the following ... 

Tensile strength, which is a measure of the ability of a polymer to withstand pulling stresses, is usually measured using a dumbbell-shaped specimen (ASTM D-638-72 Figures 14.11 and 14.12). These test specimens are conditioned under standard conditions of humidity and temperature before testing. 

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