Disclosed is an anti-buckling jig of a fracture toughness test. The anti-buckling jig includes: a first jig unit provided in a form of surrounding one side surface of a specimen; a second jig unit provided in a form of surrounding the other side surface of the specimen; and a screw provided to allow the first jig unit and the second jig unit to be coupled to each other. During the fracture toughness test of the specimen, the first jig unit and the second jig unit simultaneously support both sides of the specimen, so that the specimen is cracked in a single direction.

To further enhance the evaluation accuracy of a delayed fracture. Focusing on the fact that a calculated stress value serving as the reference for the occurrence of the delayed fracture changes depending on analysis conditions of a forming analysis, a value obtained by changing a stress value serving as the reference for the occurrence of the delayed fracture according to the analysis conditions for analyzing an intended formed article (article for practical use) is used as the reference for evaluating the delayed fracture. For example, analysis conditions of a forming analysis in an evaluation test of the delayed fracture are matched with analysis conditions of a forming analysis of an article for practical use represented by an actual automobile component.

A method of testing a material sample of a type used in a wall of a structure in a standard test for in-plane fracture toughness evaluation. The method comprises obtaining a sample having a lateral length no larger than a thickness of the wall of the structure, shaping the sample to have (a) a bottom surface, (b) a profiled top surface having a central notch, (c) a first coupling feature on a first side of the central notch, and (d) a second coupling feature on a second side of the central notch, assembling a test specimen which increases the width of the sample beyond the lateral width by coupling a first lateral extension to the first coupling feature and a second lateral extension to the second coupling feature, and applying a standard fracture toughness test to the so-assembled test specimen and sample to evaluate the fracture toughness of the sample.

A glass stress test method includes breaking a glass, analyzing a shape of a crack of a broken portion of the glass in a plan view, finding a breakage origin of the glass based on the shape of the crack in the plan view, analyzing a cross-section of the breakage origin, and calculating a stress of the glass based on a cross-sectional analysis result of the breakage origin. The stress of the glass is calculated as a value proportional to a floor constant defined by a condition of a floor surface disposed when the glass is broken.

A method of testing a material sample of a type used in a wall of a structure in a standard test for in-plane fracture toughness evaluation. The method comprises obtaining a sample having a lateral length no larger than a thickness of the wall of the structure, shaping the sample to have (a) a bottom surface, (b) a profiled top surface having a central notch, (c) a first coupling feature on a first side of the central notch, and (d) a second coupling feature on a second side of the central notch, assembling a test specimen which increases the width of the sample beyond the lateral width by coupling a first lateral extension to the first coupling feature and a second lateral extension to the second coupling feature, and applying a standard fracture toughness test to the so-assembled test specimen and sample to evaluate the fracture toughness of the sample.

The present disclosure involves a method for determining the critical local expansion of a component with an eye toward the appearance of edge cracks based on an expansion of the component in the shaping process. Given a local expansion of the component at the edges that is smaller than the critical local expansion, no edge cracks arise that are larger than 1 m. In particular, at least one expansion test is performed with at least one test component, and a critical overall expansion is determined with the at least one expansion test. The local maximum expansion of the test component is determined that the test component exhibits at the time of the critical overall expansion of the test component, and the local maximum expansion is the critical local expansion.

An indenter is made of polycrystalline diamond and has a tip having a spherical surface with a radius of 10 to 2000 m.

A method for determining rock properties includes running a downhole tool into a wellbore formed from a terranean surface to a subterranean zone that includes an underground rock formation, the downhole tool including one or more protrusions coupled with at least one expandable member of the downhole tool, the one or more protrusions including memory metal; actuating the downhole tool, at a location in the wellbore adjacent the underground rock formation, to adjust the at least one expandable member to move the one or more protrusions into or near contact with the underground rock formation; activating the one or more protrusions to fracture the underground rock formation through forcible contact between the one or more protrusions and the underground rock formation; determining a wellbore pressure increase at the location in the wellbore based on the fracture; and determining one or more properties of the underground rock formation based at least in part on the determined wellbore pressure increase.

A method for determining fatigue properties of a structure includes mounting the structure in a load frame. The structure has a crack with a crack size. The method includes applying repeatedly an adjustable stimulus to the structure over multiple cycles. The adjustable stimulus is an adjustable load or an adjustable displacement applied to the structure. The method further includes storing the crack size at a start of the cycles, measuring a response of the structure subjected to the adjustable stimulus in each cycle, updating the crack size based on the response in each cycle, and updating the adjustable stimulus in each cycle. The adjustable stimulus as updated maintains a strain energy release rate approximately constant based on the crack size. The method includes calculating a growth rate of a crack propagation in the structure based on the response in each cycle, and storing the growth rate in a file.

The fatigue cracking machine for circumferential notched tensile (CNT) specimens is a device for pre-cracking a CNT specimen prior to SCC testing. The machine uses a specimen holding cylinder attached to the shaft of a motor by a coupling, the holding cylinder being rotatably mounted in a bearing mounted in a bearing support fixed to a platform. The machine also uses a load cylinder rotatably mounted in a load bearing supported in a load fork, the load fork having a shaft adjustably mounted in a bearing support block. A dial indicator is fixed to a post rigidly mounted on the platform with the indicator's plunger bearing against the load bearing. An adjustment bolt bears against the end of the load fork shaft to displace the load bearing, applying a bending force to the specimen while it rotates, the displacement being measured by the dial indicator.