According to one implementation, a structural health monitoring system includes an ultrasonic transducer, an ultrasonic sensor, a strain sensor and a signal processing part. The ultrasonic transducer oscillates an ultrasonic wave to the first inspection area. The ultrasonic sensor detects a waveform of at least one of a transmission wave of the ultrasonic wave and a reflected wave of the ultrasonic wave. The transmission wave has transmitted the first inspection area. The reflected wave has been reflected in the first inspection area. The strain sensor detects a strain amount of the second inspection area. The signal processing part obtains at least one index, representing health of the structural object including the first inspection area and the second inspection area, based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor.

The present disclosure provides a stress gradient loading test apparatus and a method of accurately determining loading energy, relating to the technical field of a rock mechanical test. The apparatus includes an upper pressure-bearing plate, a specimen fixing device, a stress transfer device, and a simulation specimen. A computer processes stress and strain monitoring data. The stress transfer device includes a plurality of plate-like high strength materials in combination. A simulation roadway is opened in the simulation specimen, and a strain gauge and a stress sensor are disposed on the simulation specimen. In a test using the apparatus, stress gradient loading is realized and elastic strain energy is calculated by the plate-like high strength materials with different stiffnesses of the stress transfer device, and loading energy acting on the simulation specimen is calculated in combination with energy applied by a tester.

A true triaxial testing system for disturbance experiment with broadband and low amplitude of a high pressure hard rock includes a low-frequency disturbance true triaxial mechanism, a variable-frequency low-speed disturbance rod mechanism and a rapid single-side unloading type specimen box. The low-frequency disturbance true triaxial mechanism and the variable-frequency low-speed disturbance rod mechanism are distributed along a straight line. The low-frequency disturbance true triaxial mechanism is independently used or cooperates with the variable-frequency low-speed disturbance rod mechanism for use. The rapid single-side unloading type specimen box cooperates with the low-frequency disturbance true triaxial mechanism for use.

An apparatus to determine the swollen cross-link density of a polymeric specimen. The apparatus includes a support structure, a fluid-holding structure to hold a solvent, a first gripping assembly engaged with a weight scale and adapted to grip a specimen and a second gripping assembly adapted to grip the specimen. The fluid-holding structure is attached to a multi-stage device attached to the support structure and displaceable upward or downward. A mechanism supported by the support structure and engaged with the multi-stage device and configured to displace the multi-stage device in fine gradations. When a specimen is gripped by the gripping assemblies and submerged in the solvent and the mechanism displaces the multi-stage device downward, a tensile force is exerted on the specimen. The tensile force is measured by a displacement gauge.

The present disclosure provides a stress gradient loading test apparatus and a method of accurately determining loading energy, relating to the technical field of a rock mechanical test. The apparatus includes an upper pressure-bearing plate, a specimen fixing device, a stress transfer device, and a simulation specimen. A computer processes stress and strain monitoring data. The stress transfer device includes a plurality of plate-like high strength materials in combination. A simulation roadway is opened in the simulation specimen, and a strain gauge and a stress sensor are disposed on the simulation specimen. In a test using the apparatus, stress gradient loading is realized and elastic strain energy is calculated by the plate-like high strength materials with different stiffnesses of the stress transfer device, and loading energy acting on the simulation specimen is calculated in combination with energy applied by a tester.

A material testing machine is provided. The material testing machine includes a force detector that detects the testing force that acts on the target to be tested; a displacement detector that detects displacement generated in the target to be tested; and a controller that controls the load mechanism. The controller includes: a differential displacement calculator that obtains a differential displacement value from a value of the displacement detected by the displacement detector and a target displacement value that has been set in advance as a test condition; and a display controller that displays, on a display device, a differential displacement graph indicating, in a form of a graph, time-series data of the differential displacement value calculated by the differential displacement calculator.

A hardness tester that loads a predetermined test force and forms an indentation in a surface of a sample using an indenter, and measures the hardness of the sample by measuring dimensions of the indentation includes a CCD camera that acquires an image of the surface of the sample before and after the indentation is formed. The CPU can execute a plurality of indentation region extraction processes that use mutually distinct methods, the indentation region extraction processes each extracting an indentation region based on the images acquired by the CCD camera. The CPU also makes a determination determining whether the indentation region extracted by the plurality of indentation region extraction processes matches a predefined reference indentation region, and based on an indentation region that is determined to match, the CPU calculates the hardness of the sample.

The invention discloses an experimental test method for subcritical propagation rate of rock fractures based on triaxial stress-strain curve, including: Step 1: preparing test sample core for experiment; Step 2: putting core into triaxial rock mechanics test system, applying constant radial confining pressure to core, and applying axial stress in the axial direction until the core is macroscopically damaged; recording experimental parameters of axial stress, strain and corresponding loading time of the core; Step 3: drawing stress-strain curve of the test core according to detection data points of axial stress and axial strain; Step 4: in the stress-strain curve of the test core, starting time and ending time of the subcritical propagation stage of fractures inside the core correspond to the initiation stress σci and damage stress σcd, respectively, and calculating subcritical propagation rate of the subcritical fracture propagation stage of the test core.

The invention discloses an experimental test method for subcritical propagation rate of rock fractures based on triaxial stress-strain curve, including: Step 1: preparing test sample core for experiment; Step 2: putting core into triaxial rock mechanics test system, applying constant radial confining pressure to core, and applying axial stress in the axial direction until the core is macroscopically damaged; recording experimental parameters of axial stress, strain and corresponding loading time of the core; Step 3: drawing stress-strain curve of the test core according to detection data points of axial stress and axial strain; Step 4: in the stress-strain curve of the test core, starting time and ending time of the subcritical propagation stage of fractures inside the core correspond to the initiation stress σci and damage stress σcd, respectively, and calculating subcritical propagation rate of the subcritical fracture propagation stage of the test core.

Methods of using micro-specimens for testing an additive manufactured material or a part made from the additive manufactured material. The methods include testing small and large test specimens taken from an additive manufactured part and from a blank constructed from the additive manufactured material. Correction factors based on the test specimens are calculated and applied to a calculated material property of the additive manufactured material.