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4.1 The purpose of this test is to obtain, by means of a specified laboratory procedure, the values of the equilibrium moisture content at higher RH levels ((≈ 95 to 100%). These values are used either as means to characterize the material or as material characteristics needed as input to appropriate computer models that can simulate wetting or drying potential of individual building materials or material assemblies under specified environmental conditions.1.1 This test method specifies a laboratory procedure for the determination of the water retention curve (or moisture storage capacity) of porous building materials at very high relative humidity (RH) levels (≈ 95 to 100% RH) corresponding to the capillary moisture region of the sorption isotherm. This is achieved by using the pressure plate test apparatus. This technique was originally developed to study soil moisture content and eventually had been adapted to building construction materials.1.2 At higher RH levels (≈ 95 to 100% RH) of the sorption isotherm (see Test Method C1498), use of climatic chamber is not an option. This technique uses overpressure to extract water out of the pore structure of porous materials until equilibrium between the moisture content in the specimens and the corresponding overpressure is achieved. Using the pressure plate extractors, equilibrium can only be reached by desorption.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 A J-R curve produced in accordance with this test method characterizes the crack growth resistances of a wide range of tough polymers and polymer blends (1-5)4 that cannot be obtained in sufficient size and thickness for valid characterization by linear elastic fracture mechanics in Test Methods D5045.5.2 The J-R curve characterizes, within the limits set forth in this test method, the resistance of a polymeric material to slow stable crack growth after initiation from a preexisting sharp flaw.5.3 A J-R curve can be used as an index of material toughness for blend or alloy design, material selection, materials processing, and quality assurance (6).5.4 The J-R curves from bend specimens represent lower bound estimates of J capacity as a function of crack extension, and have been observed to be conservative relative to those obtained from specimen configurations under tensile loading.5.5 The J-R curves for a given material of constant microstructure tend to exhibit lower slope (flatter) with increasing thickness. Thus, it is recommended that the largest possible specimen with representative microstructure be used.5.6 The J-R curve can be used to assess the stability of cracks in structures in the presence of ductile tearing, with awareness of the differences that may exist between laboratory test and field conditions.5.7 A J-R curve may depend on the orientation and propagation of the crack in relation to the anisotropy of the material which may be induced by specimen fabrication methods.5.8 Because of the possibility of rate dependence of crack growth resistance, J-R curves can be determined at displacement rates other than that specified in this test method (7).1.1 This test method covers the determination of the J-integral versus crack growth resistance (J-R) curves for polymeric materials.1.2 This test method is intended to characterize the slow, stable crack growth resistance of bend-type specimens in such a manner that it is geometry insensitive within limits set forth in this test method.1.3 The recommended specimens are the three-point bend (SE(B)) and pin-loaded compact tension (C(T)) specimens. Both specimens have in-plane dimensions of constant proportionality for all sizes. Specimen configurations other than those recommended in this test method may require different procedures and validity requirements.1.4 This test method describes a multiple specimen method that requires optical measurement of crack extension from fracture surfaces. It is not recommended for use with materials in which the crack front cannot be distinguished from additional deformation processes in advance of the crack tip.1.5 The values stated in SI units are to be regarded as the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: There is no known ISO equivalent to this standard.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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3.1 This test method establishes the procedure to be used to measure the force necessary to draw an archery bow from brace height to the full draw position, and the holding force necessary to retain the bow string when the bow is let-down from full draw to brace height. The force values taken at increments of draw length are then plotted versus draw length using rectangular coordinates. The resulting curves are known as the force-draw curve and the let-down curve.3.2 The force-draw curve is used to determine the energy that the limbs of the bow store when it is drawn. The area under the curve between the positions of brace height and full draw can be expressed as stored energy.3.3 The let-down curve is used to determine the energy required to restrain the bowstring as the bow is let-down from full draw to brace height. The energy represented by the area under the curve can be subtracted from the stored energy in order to establish the static hysteresis of the bow system.1.1 This test method covers the procedure to be used to determine the force-draw and let-down curves for archery bows.1.2 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 This practice is intended to provide fundamental direction for the calibration, drift correction, and periodic control of the analytical curves for spark atomic emission spectrometers.5.2 It is assumed that this practice will be used by trained operators capable of performing the procedures described herein.1.1 This practice provides direction for establishing and controlling spark atomic emission spectrochemical analytical curves. The generation of analytical curves and their control are considered as separate though interrelated operations. This practice is applicable to spark atomic emission spectrometers.NOTE 1: X-ray fluorescence spectrometric applications are no longer covered by this practice. See Guides E1361 and E1621 for discussion of this technique.1.1.1 Since software programs are readily available to compute multiple linear regressions that can be used to generate analytical curves and since most instruments include this feature, this practice does not address this procedure. However, some recommendations are given to evaluate the equations that are generated.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 ASTM standard test methods that involve sound attenuation and those test methods that involve absorption or decay rates use a noise signal to determine these quantities. The IR method using a sweep signal given in this standard practice can be referenced by these other standards to provide an alternative measurement technique. This alternative technique has the advantage of providing more reliable results in a shorter period of time.5.2 The results obtained with the noise and IR method are considered identical to within the typical measurement uncertainty for the noise method under repeatability conditions. A mandatory validation procedure is given in this practice to ensure a correct implementation of the IR method when developing software or hardware according to the requirements in this standard.5.3 To avoid ambiguity in the implementation of the IR method and to ensure consistent results across different users, this practice prescribes the values of methods and parameters to be used in the signal generation and post-processing. This is in contrast to similar standards describing this method, such as ISO 18233, which provide less guidance.1.1 This practice covers the impulse response measurement method using sweep signals, and its use to determine two important room-acoustical quantities: the difference in sound pressure levels between two positions, as used for example in standards determining transmission loss; and decay curves, as used in standards determining the decay rate or reverberation time.1.2 The practice shall be used in conjunction with test methods that use one or both of the quantities described in 1.1.1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM E2218-23 Standard Test Method for Determining Forming Limit Curves Active 发布日期 :  1970-01-01 实施日期 : 

5.1 The forming limit curve (FLC) is specific to the material sampled. It can change if the material is subjected to cold work or any annealing process. Thus, two samples from a given lot of material can produce different curves if their processing is varied.5.2 The processing history of the material must be known if the test is to be considered representative of a grade of a product.5.3 A forming limit curve (FLC) defines the maximum (limiting) strain that a given sample of a sheet metal can undergo for a range of forming conditions, such as deep drawing, plane strain, biaxial stretching, and bending over a radius in a press and die drawing operation, without developing a localized zone of thinning (localized necking) that would indicate incipient failure.5.3.1 FLCs may be obtained empirically by using a laboratory hemispherical punch biaxial stretch test and also a tension test to strain metal sheet test specimens, from a material sample, from beyond their elastic limit to just prior to localized necking and fracture.5.3.1.1 Since the location of localized necking and fracture cannot be predetermined, one or both surfaces of test specimens are covered with a pattern of gauge length measurement units, usually as squares or small diameter circles, by a suitable method such as scribing, photo-grid, or electro-etching, and then each test specimen is formed to the point of localized necking, or fracture.5.3.2 Strains in the major (e1) and minor (e2) directions are measured using individual gauge length measurement units on the pattern in the area of the localized necking or fracture.5.3.2.1 Test specimens of varied widths are used to produce a wide range of strain states in the minor (e2) direction.5.3.2.2 The major strain (e1) is determined by the capacity of the material to be stretched in one direction as simultaneous surface forces either stretch, do not change, or compress, the metal in the minor strain (e2) direction.5.3.2.3 In the tension test deformation process, the minor strains (e2) are negative, and the test specimen is narrowed both through the thickness and across its width.5.3.3 These strains are plotted on a forming limit diagram (FLD), and the forming limit curve (FLC) is drawn to connect the highest measured e1 and e2 strain combinations that include good data points.5.3.3.1 When there is intermixing and no clear distinction between good and marginal data points, a best fit curve is established to follow the maximum good data points as the FLC.5.3.4 The forming limit is established at the maximum major strain (e1) attained prior to necking.5.3.5 The FLC defines the limit of useful deformation in forming metallic sheet products.5.3.6 FLCs are known to change with material (specifically with the mechanical or formability properties developed during the processing operations used in making the material) and the thickness of the sheet metal.5.3.6.1 The strain hardening exponent (n value), defined in Test Method E646, affects the forming limit. A high n value will raise the limiting major strain (e1), allowing more stretch under positive minor strain conditions (e2 > 0).5.3.6.2 The plastic strain ratio (r value), defined in Test Method E517, affects the capacity of a material to be deep drawn. A high r value will move the minor strain (e2) into a less severe area to the left of the FLDo (e2 < 0), thus permitting deeper draws for a given major strain (e1).5.3.6.3 The thickness of the material will affect the FLC since a thicker test specimen has more volume to respond to the forming process.5.3.6.4 The properties of the steel sheet product used in determining the FLC of Fig. 3 included the n value and the r value.5.3.7 FLCs serve as a diagnostic tool for material strain analysis and have been used for evaluations of stamping operations and material selection.5.3.8 The FLC provides a graphical basis for comparison with strain distributions on parts formed by sequential press operations.5.3.9 The FLC obtained by this method follows a constant proportional strain path where there is a nominally fixed ratio of major (e1) to minor (e2) strain.5.3.9.1 There is no interrupted loading, or reversal of straining, but the rate of straining may be slowed as the test specimen approaches necking or fracture.5.3.9.2 The FLC can be used for conservatively predicting the performance of an entire class of materials provided the n value, r value, and thickness of the material used are representative of that class.5.3.10 Complex forming operations, in which the strain path changes, or the strain is not homogeneous through the metal sheet thickness, can produce limiting strains that do not agree with the forming limit obtained by this method.5.3.11 Characterization of a material's response to plastic deformation can involve strain to fracture as well as to the onset of necking. These strains are above the FLC.5.3.12 The FLC is not suitable for lot-to-lot quality assurance testing because it is specific to that sample of a material which is tested to establish the forming limit.1.1 This test method gives the procedure for constructing a forming limit curve (FLC) for a metallic sheet material by using a hemispherical deformation punch test and a uniaxial tension test to quantitatively simulate biaxial stretching and deep drawing processes.1.1.1 Fig. 1 shows an example of a forming limit curve on a schematic forming limit diagram (FLD).FIG. 1 Schematic Forming Limit DiagramNOTE 1: The upper curve represents the forming limit curve. Strains below the lower curve do not occur during forming metallic sheet products in the most stamping press operations. Curves to the left of % e2 = 0 are for constant area of the test specimen surface.1.2 FLCs are useful in evaluating press performance by metal fabrication strain analysis.1.3 The method applies to metallic sheet from 0.5 mm (0.020 in.) to 3.3 mm (0.130 in.).1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses after SI units are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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