Specimen stress

When a load is placed on a specimen, stress and strain result. Stress is the internal resistance to the load as the applied force. Strain is the amount of deformation caused by this stress, such as deflection in bending, contraction in compression, and elongation in tension. 

The same critical remarks must be made in connection with this test method with un-notched specimens as concerning long-term tensile tests on smooth geomembrane specimens stress crack formation proceeds from random weak points in the boundary region of the specimen. The type of speeimen preparation will have a significant influence on the test results. 

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. 

ASTM G 58, Practice for Preparation of Stress Corrosion Test Specimens for Weldments— This covers the manufacture and application of welded test specimens in stress corrosion testing. This practice is used to evaluate a total weldment, weld metal, or presence of notches and stress risers in weldments with respect to SCC in an environment. In addition, ASTM G 58 contains a method for evaluating the critical stress levels that will produce SCC in a weldment. The specimens are evaluated after exposure to an environment by microscopic methods. This standard includes typical specimens (stressed and tension), welding considerations, test specimen preparation, and inspection after exposure. 

NACE Standard Test Method for Testing of Metals for Resistance to Sulfide Stress Cracking in HjS Environments (TM0177) describes foiu- test methods in which specimens stressed in tension are exposed to acidified brine saturated with H2S. In Method A of this test, standard tension test specimens are used and the tensile stress is applied by either... 

Evans [777] studied the stress-corrosion behavior of continuous-fiber /U2O3/ZE4IA Mg MMC in an NaCl-potassium chromate (K2Cr04) solution. Unnotched and notched specimens stressed parallel to the fiber axis and exposed for approximately 100-1000 h in the NaCl-K2Cr04 solution retained approximately 90 % of the strength in air. The matrix alloy and the MMC with the stress aligned perpendicular to the fiber axis retained only approximately 40-60 % of the strength in air. 

The macroscopic properly of immediate practical concern is often not so much craze formation as fracture resistance. In a cracked specimen, stress is concentrated at the crack tip, and the local stress state depends on the crack length. For small global deformations, it may be expressed in terms of a stress intensity factor, K, given by Eq. (71), where a is the crack length and F is a dimensionless function of the specimen geometry [31, 32]. 

ILLIUM PD passes the ASTM B117 salt spray test. Sea water corrosion tests conducted for the U. S. Navy at Portsmouth resulted in no evidence of corrosive attack on specimens stressed at 55,000 to 75,000 psi for a period of six months. 

Stress. The force applied to produce deformation in a unit area of a test specimen. Stress is a ratio of applied load to the original cross-sectional area expressed in Ib/in.l... 

The intensity of the internally distributed forces or components of forces that resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress is expressed in force per unit area and is calculated on the basis of the original dimensions of the cross section of the specimen. Stress can be either direct (tension or compression) or shear. See also residual stress. 

Fuel systems. An early investigation of stress-corrosion cracking in boiling uranyl-sulfate solutions involved exposure of stress specimens in a small, atmospheric pressure, total reflux test evaporator [155] constructed of type-347 stainless steel. Four constant-strain type-347 stainless-steel specimens stressed to 20,000 psi by three point loading were exposed in the solution and vapor phase. The evaporator was run without aeration other than that resulting from the fact that the condenser was open to the atmosphere. 

Figure 8. Location of AE events in double-radius specimen (Stresses are calculated based on specimen width away from the notch)...

D.O. Sprowls and J.D. Walsh, Evaluating Stress-Corrosion Crack Propagation Rates in High Strength Aluminum Alloys with Bolt Loaded Precracked Double Cantilever Beam Specimens, Stress-Corrosion—New Approaches, STP 610, H.R Craig, Jr., Ed ASTM, 1976, p 143-156... 

Stresses in a cell embedded in a stack originate from different phenomena. Residual stresses build up during the cool down, after the sintering, because of the mismatches between the CTEs of the materials of the cell. The dissymmetry of the system results in curved specimens. Stresses in the cell then arise from mechanical... 

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