定价： 689元 / 折扣价： 586 元

定价： 468元 / 折扣价： 398 元 加购物车

定价： 260元 / 折扣价： 221 元 加购物车

定价： 260元 / 折扣价： 221 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 646元 / 折扣价： 550 元 加购物车

定价： 590元 / 折扣价： 502 元 加购物车

5.1 This practice for plane-strain fracture toughness testing of aluminum alloys may be used as a supplement to Test Method E399. The application of this practice is primarily intended for quality assurance and material release in cases where valid plane-strain fracture toughness data cannot be obtained per Test Method E399.5.2 It must be understood that the interpretations and guidelines in this practice do not alter the validity requirements of Test Method E399 or promote the designation of data that are invalid according to Test Method E399 to a “valid” condition. This practice is primarily concerned with cases where it is not possible or practical to obtain valid data, but where material release judgments must be made against specified fracture toughness values. Where it is possible to obtain a valid plane-strain fracture toughness value by replacement testing according to Test Method E399, that is the preferred approach.1.1 This practice is applicable to the fracture toughness testing of all aluminum alloys, tempers, and products, especially in cases where the tests are being made to establish whether or not individual lots meet the requirements of specifications and should be released to customers.1.2 Test Method E399 is the basic test method to be used for plane-strain fracture toughness testing of aluminum alloys. The purpose of this practice is to provide supplementary information for plane-strain fracture toughness of aluminum alloys in three main areas:1.2.1 Specimen sampling,1.2.2 Specimen size selection, and1.2.3 Interpretation of invalid test results.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3.1 Exception—Certain inch-pound values given in parentheses are provided for information only.1.4 This standard is currently written to accommodate only C(T) specimens.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.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Autogenous strain is the self-created bulk strain of cement paste, mortar, or concrete during hardening at constant temperature. In conventional concrete, autogenous shrinkage strain is generally negligible, but in concrete with low water-cementitious materials ratio (w/cm) or with silica fume it may be considerable (1).5 Restraint of the autogenous strain by aggregates or adjoining structural members may result in formation of micro and macro cracks that impair strength, durability and aesthetics. Cracks may also be a problem with regard to hygienic cleaning of surfaces.5.2 An accurate measurement of the autogenous strain of cementitious mixtures with low w/cm is important for evaluating the risk of early-age cracking of concrete structures. Measurements of autogenous strain have been carried out using either volumetric or linear methods. Both methods may show evidence of significant artifacts (1); therefore, results of the two methods may disagree considerably if not carried out properly.5.3 A sealed, flexible corrugated mold system (2) combines the advantages of linear and volumetric measurement of autogenous strain, while avoiding most of their disadvantages. The mold effectively prevents moisture loss and minimizes restraint to volume change during hardening. Moreover, results obtained with the corrugated mold system agree with those from the volumetric method, once some artifacts, in particular water absorption through the membrane used to contain the test specimen, have been eliminated in the latter (3,4). The corrugated mold system is easier to use and shows better repeatability than the volumetric technique (3,4). Measurements with the corrugated mold system are in good agreement with unrestrained length change measurements obtained using Test Method C157/C157M with sealed specimens (5); however, Test Method C157/C157M does not allow measurement of the shrinkage occurring before 24 h (5).5.4 This test method can be used to evaluate the effects of cementitious materials, admixtures, and mixture proportions on autogenous shrinkage strain of paste or mortar specimens.5.5 The autogenous shrinkage strain of mortar specimens will be less than that of paste specimens for the same w/cm. The autogenous shrinkage strain of concrete will be less than that of mortar for the same w/cm. The nominal maximum aggregate size for mortar used in this test method is 4.75 mm.1.1 This test method measures the bulk strain of a sealed cement paste or mortar specimen, including those containing admixtures, various supplementary cementitious materials (SCM), and other fine materials, at constant temperature and not subjected to external forces, from the time of final setting until a specified age. This strain is known as autogenous strain. Autogenous strain is most significant in concrete with low water-cementitious materials ratio (w/cm) (See Note 1).NOTE 1: A low water-cementitious materials ratio (w/cm) can be considered to be a water to cement ratio of 0.40 or lower for this test.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of 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. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.2)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.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 This practice is designed to aid those interested in the engineering properties of roofing membranes.4.2 The data obtained will not permit prediction of the service life of a membrane under field conditions. The data will provide a basis for study of the mechanical properties of the membrane. Note that if strain rates, specimen dimensions, initial clear distance between clamps, or temperatures and moisture contents are varied, the data may not be strictly comparable.1.1 This practice is a guide for determining the load-strain properties of roofing membranes and their components at various temperatures. Test specimens may be prepared in the laboratory or cut from samples obtained in the field.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.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.

定价： 515元 / 折扣价： 438 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 646元 / 折扣价： 550 元 加购物车

4.1 The property KIc, determined by Test Method E399 or ISO 12135, characterizes a material's resistance to fracture in a neutral environment and in the presence of a sharp crack subjected to an applied opening force or moment within a field of high constraint to lateral plastic flow (plane strain condition). A KIc value is considered to be a lower limiting value of fracture toughness associated with the plane strain state.4.1.1 Thermal quenching processes used with precipitation hardened aluminum alloy products can introduce significant residual stresses.5 Mechanical stress relief procedures (stretching, compression) are commonly used to relieve these residual stresses in products with simple shapes. However, in the case of mill products with thick cross-sections (for example, heavy gauge plate or large hand forgings) or complex shapes (for example, closed die forgings, complex open die forgings, stepped extrusions, castings), complete mechanical stress relief is not always possible. In other instances residual stresses may be introduced into a product during fabrication operations such as straightening, forming, or welding operations.NOTE 1: For the purposes of this guide, only bulk residual stress is considered (that is, of the type typically created during a quench process for thermal heat treatment) and not engineered residual stress, such as from shot peening or cold hole expansion.4.1.2 Specimens taken from such products that contain residual stress will likewise themselves contain residual stress. While the act of specimen extraction in itself partially relieves and redistributes the pattern of original stress, the remaining magnitude can still be appreciable enough to cause significant error in the test result.4.1.3 Residual stress is a non-proportional internal stress that is superimposed on the applied stress and results in an actual crack-tip stress-intensity factor that is different from one based solely on externally applied forces or displacements, and residual stress can bias the toughness measurement. Conceptually, compressive residual stress in the region of the crack tip must be overcome by the applied force before the crack tip experiences tensile stresses, thus biasing the KQ or KIc measurement to a higher value, potentially producing a non-lower-bound toughness value. Quantitatively, the effect depends on stress equilibrium for the continuously varying residual stress field and the associated crack tip response. Conversely, a tensile residual stress is additive to the applied force and biases the measured KQ or Kic result to a lower value, potentially under-representing the material “true” toughness capability.4.1.4 Tests that utilize deep edge-notched specimens such as the compact tension C(T) are particularly sensitive to distortion during specimen machining when substantial residual stress is present. In general, for those cases where such residual stresses are thermal quench induced, the resulting KIc or KQ result is typically biased upward (that is, KQ is higher than that which would have been achieved in a residual stress-free specimen). The inflated values result from the redistribution of residual stress during specimen machining and excessive fatigue precrack front curvature caused by variable residual stresses across the crack front.64.2 This guide can serve the following purposes:4.2.1 Provide warning signs that the measured value of KIc has been biased by residual stresses and may not be a lower limit value of fracture toughness.4.2.2 Provide experimental methods that can be used to minimize the effect of residual stress on measured fracture toughness values.4.2.3 Suggest methods that can be used to correct residual stress influenced values of fracture toughness to values that approximate a fracture toughness value representative of a test performed without residual stress bias.1.1 This guide covers supplementary guidelines for plane-strain fracture toughness testing of aluminum products for which complete stress relief is not practicable. Guidelines for recognizing when residual stresses may be significantly biasing test results are presented, as well as methods for minimizing the effects of residual stress during testing. This guide also provides guidelines for an empirical correction as well as interpretation of data produced during the testing of these products. Test Method E399 is the standard test method to be used for plane-strain fracture toughness testing of aluminum alloys.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.

定价： 515元 / 折扣价： 438 元 加购物车

定价： 646元 / 折扣价： 550 元 加购物车

定价： 590元 / 折扣价： 502 元 加购物车