Part 1: An Analytical Comparison Of Short Crack And Deep Crack CTOD Fracture Specimens Of An A36 Steel<\/b><\/p>\n
The effect of crack-depth to specimen-width ratio on Crack Tip Opening Displacement (CTOD) fracture toughness is an important consideration in relating the results of laboratory tests to the behavior of actual structures. Deeply cracked, three-point bend specimens with crack-depth to specimen-width ratios (a\/W) of 0.50 are most often used in laboratory tests. However, to evaluate specific weld microstructures or the behavior of structures with shallow surface cracks, specimens with a\/W ratios much less than 0.50 often are required. Laboratory tests reveal that three-point bend specimens with short cracks (a\/W = 0.15) exhibit significantly larger critical CTOD values than specimens with deep cracks (a\/W = 0.5) up to the point of ductile initiation. <\/p>\n
In this study, finite element analyses are employed to compare the elastic-plastic behavior of square (cross-section) three-point bend specimens with crack-depth to specimen- width ratios (a\/W) ranging between 0.50 and 0.05. The two-dimensional analysis of the specimen with an a\/W ratio of 0.15 reveals a fundamental change in the deformation pattern from the deep crack deformation pattern. The plastic zone extends to the free surface behind the crack concurrent with the development of a plastic hinge. For shorter cracks (a\/W = 0.10 and 0.05), the plastic zone extends to the free surface behind the crack prior to the development of a plastic hinge. For longer cracks (a\/W > 0.20), a plastic hinge develops before the plastic zone extends to the free surface behind the crack. <\/p>\n
Part 2: The Effects Of Crack Depth On Elastic-Plastic CTOD Fracture Toughness<\/b><\/p>\n
The potential effects of crack depth (a\/W ratio) on elastic-plastic measures of fracture toughness must be known to correlate properly the results of laboratory tests with the behavior of flawed structural components. Deep crack specimens (a\/W = 0.50) are used extensively to provide the most severe crack-tip conditions and therefore conservative (lower-bound) measures of fracture toughness. A short crack specimen (a\/W << 0.50) is frequently employed when a deeply cracked specimen is either inappropriate or impossible to obtain in the CTOD specimen. Specific examples are the testing of particular microstructures in weldments, local brittle zones (LBZ's), and in-service structures with shallow or short cracks, particularly surface flaws. This study compares the CTOD results of square (cross-section) three-point bend specimens with short cracks (a\/W = 0.15) to the CTOD results of specimens with deep cracks (a\/W = 0.50). <\/p>\n
Part 3: A Comparison Of The J-Integral And CTOD Parameters For Short Crack Specimen Testing<\/b><\/p>\n
Two of the elastic-plastic fracture mechanics (EPFM) test methods widely used in the transition region where linear-elastic —, behavior is no longer applicable are the J-integral and the crack tip opening displacement (CTOD) test methods. The J-integral test procedure is restricted to temperature regions above the initiation of ductile tearing and is also limited to crack-depth to specimen-width ratios (a\/W) between 0.50 and 0.75. In contrast, the CTOD test procedure can be used for testing throughout the entire temperature-toughness transition region from brittle to fully ductile behavior. Also, extensive research is being conducted to extend the CTOD test procedure to the testing of short crack specimens (a\/W ratios of approximately 0.15).<\/p>\n","protected":false},"excerpt":{"rendered":"
Part 1: An Analytical Comparison of Short Crack and Deep Crack CTOD Fracture Specimens of an A36 Steel; Part 2: The Effects of Crack Depth on Elastic-Plastic CTOD Fracture Toughness; Part 3: A Comparison of the J-Integral and CTOD Parameters for Short Crack Specimen Testing<\/b><\/p>\n\n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n WRC<\/b><\/a><\/td>\n 1990<\/td>\n 42<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":696768,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2677],"product_tag":[],"class_list":{"0":"post-696759","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-wrc","8":"first","9":"instock","10":"sold-individually","11":"shipping-taxable","12":"purchasable","13":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/696759","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/696768"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=696759"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=696759"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=696759"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}