A method for determining material parameters includes applying a character grid over a planar sample, clamping the planar sample in a frame in accordance with directions of orthotropy of the planar sample; collecting a first set of data that describes a first position of the character grid; applying predetermined normal and shear stresses to the planar sample thereby bringing the planar sample into a deformed state and changing the position of the character grid; collecting a second set of data that describes a second position of the character grid, determining a relative position change of the character grid by correlating the collected first set of data and the second set of data; determining a relative displacement and a current distortion state of the planar sample; determining a deformation equilibrium of the deformed state of the planar sample; and calculating the material parameters from the deformation equilibrium.

A method for manufacturing a press formed part, the method including specifying stretch flange limit strain in a metal sheet by using strain gradient in a radial direction and strain gradient in a sheet thickness direction. The strain gradient in the radial direction being directed from an end portion of the metal sheet at a time a press load is applied. The strain gradient in the sheet thickness direction being a direction of the metal sheet that intersects a loading direction. Additionally, the stretch flange limit strain satisfies the formula .sub.lim=A[a.Math..sub./r+b.Math..sub./t]+c, where .sub.lim represents the stretch flange limit strain in a tangential direction of the sheet edge, .sub./r represents the strain gradient in the radial direction, .sub./t represents the strain gradient in the sheet thickness direction, A, a, and b represent influence coefficients, and c represents the limit strain at a time the strain gradient is zero.

A bi-axial testing apparatus, system and method may be used with known uni-axial material testing machines to perform biaxial displacement control (e.g., compressive and/or tensile) testing on a specimen. As such, the apparatus, system and method may be capable of providing bi-axial compressive or tensile loads with uni-axial motion and only one actuator. The specimen may be a cubic specimen including, without limitation, 3D printed cellular materials, composite materials, foams, bio-medical materials, and the like. The apparatus generally includes a first or top fixture forming a first re-entrant surface and a second or bottom fixture forming a second re-entrant surface. When the fixtures are mounted, the re-entrant surfaces form a testing space in the center to accommodate a specimen to be tested and the re-entrant surfaces provide testing forces in two axes in response to an actuator providing motion of at least one of the fixtures in one axis.

A wide-temperature-range uniaxial and biaxial compression test device in a high-pressure hydrogen environment is provided. An upper computer is interacted with a temperature sensor, a gas pressure sensor, test pressure sensors, displacement sensors, an oxygen/hydrogen concentration monitor, a hydrogen filling system, a vacuum extraction system, a DIC test system, and the other components. The upper computer is used to achieve high-pressure hydrogen environment wide-temperature-range uniaxial and biaxial compression test based on different test modes. Tested engineering stress-strain data is processed to obtain real stress-strain data of rubber, and then the real stress-strain data is processed through a corresponding database to screen out a constitutive model capable of best characterizing the nonlinearity of the rubber specimen. Meanwhile, a strain distribution nephogram generated by a test result of a sample material can be analyzed, thus obtaining a deformation behavior and a failure fracture mechanism of the sample material.

Methods and systems facilitate measuring flow properties of a material, such as biomass materials, that include different material particles. Sample holding plates securely hold material particles and secure them to sample holders. A normal force actuator applies a normal force between material particles held by the sample holding plates and a sliding force actuator applies a sliding force. Normal and sliding force sensors monitor the transmitted forces, allowing a processor to determine adhesion and friction characteristics between particles held by the first and second sample holding plates.

A wrinkle generation determination method for a press formed part includes acquiring, for each load ratio in in-plane biaxial directions, a relationship between an in-plane biaxial strain generated in a process of inducing out-of-plane buckling in a measurement part and a load, acquiring an in-plane biaxial strain at a point where a primary differential coefficient of an in-plane uniaxial strain on which a compressive load acts becomes local maximum as a stable behavior limit strain, and acquiring a stable behavior limit line that will be an index for wrinkle generation under a biaxial stress condition by plotting, on two-dimensional coordinates, the stable behavior limit strain acquired for each load ratio in a biaxial stress test in which a load in the in-plane biaxial directions is applied to a cruciform test piece for biaxial test so as to induce out-of-plane buckling in the measurement part.

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.

A system includes: a tension member having a first end and a second end, where the first end of the tension member is connected to a first loading member and the second end of the tension member is connected to a second loading member; a first actuator configured to translate the first loading member, such that a tensile load is applied to the tension member along a first direction; a second actuator configured to translate the second loading member in two or more second directions that are substantially transverse to the first direction; and a control system that is configured to control the second actuator, such that the second loading member oscillates between the two or more second directions, where the oscillation of the second loading member causes the tension member to vibrate at a frequency.

A rig for testing thermomechanical loads comprises grip portions for gripping a test specimen, and a frame that join the grip portions to each other, the thermal expansion coefficient of the grip portions being greater than the thermal expansion coefficient of the frame. The frame may be made from metal.

The invention discloses a biaxial test device, comprising: a bracket, a container, a sample setting assembly and a press, etc. Before use, the sample is installed between two limit plates. On the basis of applying confining pressure, the press is started, and the pressure rod moves vertically downward and applies a vertical downward load to the sample. When the sample is subjected to the vertical downward load, axial compression and radial deformation will occur. At this time, the radial deformation of the sample on both sides of the limit plates is limited, and expansion occurs on both sides without the limit plates. Subsequently, under the joint action of the confining pressure and the limit plates, the sample undergoes plane strain. Since the container and the limit plates are both in a transparent state, the side section state of the sample when plane strain occurs can be well observed. At the same time, the multiphase mixed fluid in the mixing container penetrates into the rock sample inside the sample and flows out through an output pipeline and is tested and analyzed by external equipment, so that the potential influence of multiphase seepage on the mechanical behavior of rock mass can be studied under plane strain conditions.