A dual-direction synchronous loading method for a true-triaxial test apparatus includes the following steps: Step S1, loading a sample and adjusting the sample at a center of a sample box and a rigid loading frame; Step S2, setting parameters and sending action instructions through a computer control panel; and Step S3, collecting load signals collected by each sensor acquired by a PID controller, and coordinating a size of triaxial dual-direction loading loads to realize a single instruction dual-direction synchronous loading. The method ensures that a rock sample is kept at a center of a pressure chamber before being loaded, so that a focus of a loading axis is always at a same position as a center of the sample in space, and the function of synchronous loading of two loading actuators in the same direction under a single instruction can be achieved.

Methods and apparatuses for multiple degree-of-freedom fatigue testing of a specimen. The apparatus includes a first platform, a second platform, a plurality of actuator assemblies, a load cell, a mounting plate, a specimen support, a direct-strain imaging system, and a local sense and control system. Each actuator assembly includes a servo-control, a position encoder, and a piston that is constructed to move in a linear direction in accordance with the servo-control. Each piston is rotatably connected to the second platform. The load cell is connected to the second platform and constructed to output force measurements in three orthogonal directions and torque measurements about the three orthogonal directions. The mounting plate is constructed to hold a portion a specimen. The specimen support is constructed to hold another portion of the specimen. The direct-strain-imaging system includes a camera that is constructed to record a plurality of images of the specimen during fatigue testing. The local sense and control system constructed to receive: a loading specification, the force measurements and torque measurements from the load cell, and position information from each position encoder, and output control commands to each servo-control of the plurality of actuator assemblies based on the received loading specification. The control commands are updated in time in accordance with the position information from each position encoder and the force measurements and torque measurements from the load cell.

An ultrahigh pressure true three-dimensional non-uniform loading/unloading and steady pressure model test system in which an ultrahigh pressure true three-dimensional non-uniform loading/unloading device is arranged in a combined bench counterforce device and used for carrying out ultrahigh pressure true three-dimensional loading/unloading on a test model, and an intelligent hydraulic loading/unloading and steady pressure numerical control system is connected with the ultrahigh pressure true three-dimensional non-uniform loading/unloading device via a high-pressure oil pipe; the ultrahigh pressure true three-dimensional non-uniform loading/unloading device is controlled in a digital servo manner via an input instruction of the intelligent hydraulic loading/unloading and steady pressure numerical control system to carry out ultrahigh pressure true three-dimensional gradient non-uniform loading/unloading and steady pressure control; an automatic model displacement test system automatically acquires the displacement of any part inside the model; and a high-definition multi-probe peeping system observes a cavern excavation deformation and failure process dynamically in real time.

A method of controlling a mechanical testing instrument includes estimating a young's modulus, and applying force during a first time interval then comparing distance measured to expected distance; predicting a distance based on a first slope applying displacement distance and recalculating the slope; providing a corrected force applied for the proper displacement based on measured modulus and correction factor and adjusting into time and distance coherence; applying a force versus time regime interval and predict deformation at the end of the second interval measuring true deformation distance after the next interval; calculating the true slope based on the extrapolated actual slope; calculating a slope to apply for desired distance; and repeating measurement and correction steps, using the actual slope as the prediction basis. A system for carrying out the method is also disclosed using a data acquisition board.

A composite test coupon includes a plurality of plies. The plurality of plies include first ply layers and second ply layers. The first ply layers have first fibers and a substantially uniform matrix material associated with the first fibers. The second ply layers have second fibers and a pre-stressed matrix material associated with the second fibers. The first fibers are oriented in a first direction, and the second fibers are oriented in a second direction that is different from the first direction. The pre-stressed matrix material includes stress induced cracks between the second fibers of each of the second ply layers.

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.

A vacuum system and method for inspecting a workpiece that can include use the vacuum system, where the vacuum system can include a housing defining at least a portion of a vacuum chamber, a piston within the housing that oscillates to vary a volume of the vacuum chamber, a first valve and a second valve in fluid communication with the vacuum chamber, and a hood in fluid communication with the second valve and the vacuum chamber. The vacuum system can include high-speed valves that enable vacuum system cycling and thus vacuum pressure cycling at a rapid frequency.

A method of evaluating fatigue in a hair fibre sample includes receiving fatigue testing data for the hair fibre sample for a plurality of loading cycles, in which the fatigue testing data comprises force or stress against displacement or strain data. The method also includes determining, for at least a subset of the loading cycles, a loading energy based on data from the fatigue testing data. The method also includes determining an indication of fatigue in the hair fibre sample based on the loading energy of the at least a subset of the loading cycles.

A hardness tester includes a measurer (CPU) measuring a value for a material characteristic of a sample in conjunction with formation of an indentation, an acquirer (CPU) acquiring measurement data associated with the value for the material characteristic of the sample measured by the measurer, and a determiner (CPU) accumulating a predetermined value for the material characteristic based on the measurement data acquired by the acquirer and determining a time to replace the indenter based on the accumulated value for the material characteristic.

Seat members 31 are held in a state of being movable with respect to first slide members 21 or second slide members 22 correspondingly. By rotating screws 39 in directions to increase the distances d between surfaces A of the first slide members 21 or the second slide members 22 and surfaces B of the seat members 31, chucks 25 are moved in directions to increase the distance between the chucks to apply pretension to a test piece correspondingly. When backlash in a force transmission system from a support part to the respective chucks 25 is eliminated, a biaxial tensile test is started.