Design of a biaxial tensile testing device and cruciform specimens for large plastic deformation in the central zone

Quantifying Alignment Deviations for the In-Plane Biaxial Test System via a Shape-Optimised Cruciform Specimen

“…The misalignment of the test system is the primary reason for the systematic error of the test data [ 15 ]. However, current methods cannot quantify alignment deviations of the in-plane biaxial test system, yielding that accuracy of test data could only be guaranteed by the precision of the test systems’ manufacturing and assembly [ 26 , 27 , 28 , 29 , 30 , 31 ]; the misalignment of the in-plane biaxial test systems varied from laboratory to test, incurring an extensive scatter of test data for the same material. Therefore, quantifying alignment deviations is essential for the in-plane biaxial test to gain reliable test data.…”

“…Although numerous institutions have developed various in-plane biaxial test systems, including vertical biaxial test systems [ 23 , 26 ], horizontal biaxial test systems [ 27 , 28 , 29 , 30 , 31 ], and others equipped with high-temperature furnaces [ 30 ], there is currently no practical method for assessing alignment deviations of an in-plane biaxial testing system, and no test has been conducted to determine the effect of alignment deviations on test results. Notably, integrating high-temperature furnaces to the in-biaxial tensile test system could aggravate alignment issues due to the extension of the loading chain.…”

Experimental facility for studying the physical properties of materials in a plane stress state

“…Для локализации напряжений в центральной зоне образца делают выборки круговой [26] или ромбовидной [27] формы (в указанных работах предметом исследований были композитные материалы, но этот же подход может быть применен и для стальных образцов). На распределение напряжений значительное влияние оказывают радиусы закругления углов [28].…”

Development of a biaxial tensile device in the plane for monotonic mechanical tests and cruciform specimens / Desenvolvimento de um dispositivo de tração biaxial no plano para ensaios mecânicos monotônicos e de corpos de prova cruciformes

“…Among biaxial loading methods, four are highlighted, which are the bubble, punch, Marciniak and cruciform methods. Amid these, in-plane loading with a cruciform specimen is the most widely used for studying the changes in stress curves and linear and nonlinear stress states, because unlike the other methods, flexural and/or frictional forces are not present [2].…”

“…VEZÉR and MAJOR [25] presented a device with planar movement, composed of a system of bars and cylindrical joints to perform monotonic and cyclic tests. ZHAO et al, [2] developed a device capable of promoting variable load ratios through different tilt angles (45º, 60º and 90º) of a set of interchangeable wedges. The use of wedges with a 90º angle also allows obtaining a flat deformation condition in the center of the specimen in tests with loading rates of 1:0 or 0:1.…”