定价： 515元 / 折扣价： 438 元 加购物车

5.1 Eddy current methods are used for nondestructively locating and characterizing discontinuities and geometric property variations in magnetic or nonmagnetic electrically conducting materials. Conformable eddy current sensor arrays permit examination of planar and non-planar materials but usually require suitable fixtures to hold the sensor array near the surface of the material of interest, such as a layer of foam behind the sensor array along with a rigid support structure.5.2 In operation, the sensor arrays are standardized with measurements in air or a reference part, or both. Responses measured from the sensor array may be converted into physical property values, such as lift-off, electrical conductivity, or magnetic permeability, or a combination thereof. Proper instrument operation is verified by ensuring that these measurement responses or property values are within a prescribed range. Performance verification is performed periodically. Performance verification on a discontinuity-free reference standard or regions of the material being examined that do not contain discontinuities ensures that the electrical and geometric properties, such as electrical conductivity, layer thickness, or lift-off, or a combination thereof, are appropriate for the sensor array. Performance verification on a discontinuity-containing reference standard ensures that the sensor array response to the discontinuity is appropriate.5.3 The sensor array dimensions, including the size and number of sense elements, and the operating frequency are selected based on the type of examination being performed. The depth of penetration of eddy currents into the material under examination depends upon the frequency of the signal, the electrical conductivity and magnetic permeability of the material, and some dimensions of the sensor array. The depth of penetration is equal to the conventional skin depth at high frequencies but is also related to the sensor array dimensions at low frequencies, such as the size of the drive winding and the gap distance between the drive winding and sense element array. For surface-breaking discontinuities on the surface adjacent to the sensor array, high frequencies should be used where the penetration depth is less than the thickness of the material under examination. For subsurface discontinuities or wall thickness measurements, lower frequencies and larger sensor dimensions should be used so that the depth of penetration is comparable to the material thickness.5.4 Insulating layers or coatings may be present between the sensor array and the surface of the electrically conducting material under examination. The sensitivity of a measurement to a discontinuity generally decreases as the coating thickness or lift-off, or both, increases. For eddy current sensor arrays having a linear drive conductor and a linear array of sense elements, the spacing between the drive conductor and the array of sense elements should be smaller than or comparable to the thickness of the insulating coating. For other array formats the depth of sensitivity should be verified empirically.5.5 Models for the sensor response may be used to convert responses measured from the sensor array into physical property values, such as lift-off, electrical conductivity, magnetic permeability, coating thickness, or substrate thickness, or a combination thereof. For determining two property values, one operational frequency can be used. For nonmagnetic materials and examination for crack-like discontinuities, the lift-off and electrical conductivity should be determined. For magnetic materials, when the electrical conductivity can be measured or assumed constant, then the lift-off and magnetic permeability should be determined. The thickness can only be determined if a sufficiently low excitation frequency is used where the depth of sensitivity is greater than the material thickness of interest. For determining more than two property values, measurements at operating conditions having at least two depths of penetration should be used; these different depths of penetration can be achieved by using multiple operational frequencies or multiple spatial wavelengths.5.6 Processing of the measurement response or property value data may be performed to highlight the presence of discontinuities, to reduce background noise, and to characterize detected discontinuities. As an example, a correlation filter can be applied in which a reference signature response for a discontinuity is compared to the measured responses for each sensor array element to highlight discontinuity-like defects. Care must be taken to properly account for the effect of interferences such as edges and coatings on such signatures.5.7 The measurement and analysis methods described in this guide can also be applied to applications where the sensor array is mounted against a surface or embedded within the material being examined. In that situation the sensor array response is monitored over a period of time instead of the scanning the sensor array over a specific location. This leads to the horizontal axes for the B-scans and C-scans to correspond to time or some other input associated with the test such as the number of loading cycles.1.1 This guide covers the use of conformable eddy current sensor arrays for nondestructive examination of electrically conducting materials for discontinuities and material quality. The discontinuities include surface breaking and subsurface cracks and pitting as well as near-surface and hidden-surface material loss. The material quality includes coating or layer thickness, electrical conductivity, magnetic permeability, surface roughness, and other properties that vary with the electrical conductivity or magnetic permeability.1.2 This guide is intended for use on nonmagnetic and magnetic metals as well as composite materials with an electrically conducting component, such as reinforced carbon-carbon composite or polymer matrix composites with carbon fibers.1.3 This guide applies to planar as well as non-planar materials with and without insulating coating layers.1.4 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that 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.

定价： 590元 / 折扣价： 502 元 加购物车

定价： 590元 / 折扣价： 502 元 加购物车

5.1 For ferromagnetic materials, magnetic particle examination is widely specified for the detection of surface and near-surface flaws such as cracks, laps, seams, and linearly oriented nonmetallic inclusions. Such examinations are included as mandatory requirements in some forging standards such as Specifications A508/A508M and A963/A963M.5.2 Use of alternating current as the power source for magnetic particle examination imposes a significant restriction on the detection of subsurface indications, so that the procedure is essentially limited to the finding of flaws that are open to the surface. Attention therefore is drawn to the need to have the component in the finish-machined condition before conducting the magnetic particle examination.5.3 The presence of residual magnetic fields in a component may be undesirable, and an advantage of the use of an ac power source for magnetic particle examination is that an acceptable level of demagnetization can be readily achieved.1.1 This practice covers a procedure for the magnetic particle examination of steel forgings using alternating current as the power source. The procedure will produce consistent results upon which acceptance standards can be based. This practice does not contain acceptance limits or recommended quality levels.1.2 Only alternating 50–60 cycle current shall be used as the electric power source for any of the magnetizing methods.1.3 When subsurface indications are sought in forgings, then dc magnetization in accordance with Practice A275/A275M should be used.1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. 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. Unless the order specifies the applicable “M” specification designation [SI units], the inch-pound units shall be used.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

定价： 590元 / 折扣价： 502 元 加购物车

5.1 This test method was developed for evaluating the ac magnetic properties of laminated cores made from flat-rolled magnetic materials.5.2 The reproducibility and repeatability of this test method are such that this test method is suitable for design, specification acceptance, service evaluation, and research and development.1.1 This test method covers the determination of several ac magnetic properties of laminated cores made from flat-rolled magnetic materials.1.2 This test method covers test equipment and procedures for the determination of impedance permeability and exciting power from voltage and current measurements, and core loss from wattmeter measurements. These tests are made under conditions of sinusoidal flux.1.3 This test method covers tests for two general categories (1 and 2) of cores based on size and application.1.4 Tests are provided for power and control size cores (Category 1) operating at inductions of 10 to 15 kG [1.0 to 1.5 T] and at frequencies of 50, 60, and 400 Hz.1.5 Procedures and tests are provided for coupling and matching type transformer cores (Category 2) over the range of inductions from 100 G [0.01 T] or lower to 10 kG [1.0 T] and above at 50 to 60 Hz or above when covered by suitable procurement specifications.1.6 This test method also covers tests for core loss and ac impedance permeability under incremental test conditions (ac magnetization superimposed on dc magnetization) for the above core types and at inductions up to those that cause the ac exciting current to become excessively distorted or reach values that exceed the limits of the individual test equipment components.1.7 This test method shall be used in conjunction with Practice A34/A34M and Terminology A340. It depends upon these designated documents for detailed information which will not be repeated in this test method.1.8 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this standard, SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.1.9 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.1.10 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： 646元 / 折扣价： 550 元 加购物车

定价： 590元 / 折扣价： 502 元 加购物车

定价： 646元 / 折扣价： 550 元 加购物车

5.1 The electrical properties of gate and field oxides are altered by ionizing radiation. The method for determining the dose delivered by the source irradiation is discussed in Practices E666, E668, E1249, and Guide E1894. The time dependent and dose rate effects of the ionizing radiation can be determined by comparing pre- and post-irradiation voltage shifts, ΔVot and ΔVit. This test method provides a means for evaluation of the ionizing radiation response of MOSFETs and isolation parasitic MOSFETs.5.2 The measured voltage shifts, ΔVot and ΔVit, can provide a measure of the effectiveness of processing variations on the ionizing radiation response.5.3 This technique can be used to monitor the total-dose response of a process technology.1.1 This test method covers the use of the subthreshold charge separation technique for analysis of ionizing radiation degradation of a gate dielectric in a metal-oxide-semiconductor-field-effect transistor (MOSFET) and an isolation dielectric in a parasitic MOSFET.2,3,4 The subthreshold technique is used to separate the ionizing radiation-induced inversion voltage shift, ΔVINV into voltage shifts due to oxide trapped charge, ΔVot and interface traps, ΔV it. This technique uses the pre- and post-irradiation drain to source current versus gate voltage characteristics in the MOSFET subthreshold region.1.2 Procedures are given for measuring the MOSFET subthreshold current-voltage characteristics and for the calculation of results.1.3 The application of this test method requires the MOSFET to have a substrate (body) contact.1.4 Both pre- and post-irradiation MOSFET subthreshold source or drain curves must follow an exponential dependence on gate voltage for a minimum of two decades of current.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.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.

定价： 0元 / 折扣价： 0 元

定价： 590元 / 折扣价： 502 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

定价： 0元 / 折扣价： 0 元 加购物车

Unsaturated sink current is a special parameter that is closely related to the gain of the output transistor of TTL circuits. This parameter is particularly useful in evaluating neutron degradation in TTL devices because it changes smoothly as the device degrades, and exhibits larger changes at moderate radiation levels than the standard electrical parameters.1.1 This test method covers the measurement of the unsaturated sink current of transistor-transistor logic (TTL) devices under specified conditions.1.2 Units—The values stated in the International System of Units (SI) are to be regarded as standard. No other units of measurement are included in this standard.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 and health practices and determine the applicability of regulatory limitations prior to use.

定价： 0元 / 折扣价： 0 元

定价： 646元 / 折扣价： 550 元 加购物车