Biaxial fatigue testing machine
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Biaxial fatigue testing machine
The biaxial fatigue testing machine by SINOTEST is engineered for dynamic and static mechanical testing of materials under multi-axial loading conditions. Specifically, the SZL and ZQP series enable both uniaxial and biaxial tests on plate samples, bar samples, and cruciform specimens, covering metals, composites, ceramics, and biomaterials. Furthermore, each biaxial fatigue testing system features four independently controlled servo-hydraulic actuators with synchronous displacement and force control in both orthogonal directions, achieving centering accuracy with a positioning deviation of ≤ 0.05 mm. Consequently, these planar biaxial fatigue testing machines are widely deployed in aerospace, automotive, biomedical, and advanced materials research laboratories for characterizing anisotropic mechanical behavior, fatigue life prediction, and failure mechanism analysis under realistic multi-axial stress states.
In addition to its biaxial capabilities, the system also functions as a universal electro-hydraulic servo testing machine, enabling standard uniaxial dynamic and static tests on plate and bar samples. As a result, laboratories gain a versatile platform capable of addressing a wide spectrum of mechanical testing requirements with a single instrument.
Applications and Test Specimens
The biaxial fatigue testing machine is applied to dynamic and static performance research across a diverse range of material classes. Specifically, test specimens include:
Composites
Carbon Fiber
Ceramic Matrix Composites
Metal Matrix Composites
Polymer Matrix Composites
Metals
Structural Steel
Fasteners
Metal Plate and Rods
Wire and Cable
Sheet Metal
Aluminum
Piping and Tubing
Rebar
Chain
Therefore, the SZL and ZQP series provide a comprehensive biaxial fatigue testing solution for laboratories engaged in advanced materials research, quality assurance, and failure analysis.
Technical Parameter
The biaxial fatigue testing machine series covers a wide range of load capacities and configurations:
| Parameter | SZL-20 | SZL-100 | SZL-200 | ZQP-300 |
| Max. capacity（kN） | 20 | 100 | 200 | 300 |
| Force measure range | 2%~100% | |||
| Frequency（Hz） | 0.001Hz-50Hz | |||
| Accuracy | class 1 | |||
| Displacement range（mm） | 0-150mm； | |||
| Displacement resolution（mm） | ≤0.001 | |||
| Centering accuracy（mm） | Center positioning deviation range ≤ 0.05mm; | |||
| Synchronous mode | Synchronous control of displacement and force values in four directions, or synchronization in pairs; | |||
| Deformation measurement | Strain gauge measuring system and corresponding dynamic and static strain gauges (optional) | |||
| Environmental devices | High temperature box room temperature+10 ℃ -350 ℃; High temperature furnace 800 ℃ (optional) | |||
| Dimension（mm） | 3000*3000*500 | 3170*3150*600 | 3200*3200*600 | 3300*3300*600 |
“Consequently, laboratories can select the appropriate model based on specimen size, material type, and required loading conditions.
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Special Case
SZL-100 Biaxial Tensile Testing Machine
The SZL-100 Biaxial Tensile Testing Machine adopts a servo closed-loop control mode with both force and displacement control to complete bi-directional static tensile testing of composite materials via electric cylinder actuation. Specifically, it complies with GB/T 36024-2018, the national standard for bidirectional tensile testing of thin plates and strips of metallic materials using cross-shaped specimens.
In terms of loading capability, the system achieves proportional or non-proportional loading of materials. Additionally, it employs special centering control technology to ensure precise center positioning when four actuators are loaded simultaneously in dual-axis directions—with synchronous accuracy of coaxial displacement not greater than 0.05 mm.
Furthermore, the software features data collection, curve drawing, local enlargement or reduction of curves, comparison of single or multiple curve overlay results, print preview, and manual effective revision of data. Key functional characteristics include:
Electric loading actuator for environmentally friendly operation
Flat push wedge-shaped fixture for easy operation
Compatibility with large deformation strain measurement devices and DIC (Digital Image Correlation) measurement devices
Integration with various environmental devices, such as high-low temperature chambers, lighting, and water vapor systems
Biaxial High And Low Temperature Tensile Testing Machine
The Biaxial High And Low Temperature Tensile Testing Machine is primarily designed for bi-directional static tensile testing of metals and composite materials under controlled thermal conditions. Moreover, the system supports both force and displacement closed-loop control with smooth switching between modes.
In addition, the loading method is flexible and diverse, enabling both uniaxial and biaxial tensile testing of specimens. Key functional characteristics include:
Overcurrent, overvoltage, and overtemperature hardware protection
Software overload and over-displacement protection
Full coverage from static to dynamic testing
Compact structure with a large loading space
Consequently, the entire biaxial fatigue testing machine platform can be combined with environmental accessories to complete multi-physics coupled tests for comprehensive material characterization.
Biaxial High And Low Temperature Tensile Testing Machine
The Biaxial High And Low Temperature Tensile Testing Machine is primarily designed for bi-directional static tensile testing of metals and composite materials under controlled thermal conditions. Moreover, the system supports both force and displacement closed‑loop control with smooth switching between modes.
In addition, the loading method is flexible and diverse, enabling both uniaxial and biaxial tensile testing of specimens. Key functional characteristics include:
Comprehensive Hardware Protection – Overcurrent, overvoltage, and overtemperature protection ensure safe, uninterrupted operation during long‑duration thermal tests.
Intelligent Software Safeguards – Software overload and over‑displacement protection prevent specimen and equipment damage under unexpected conditions.
Wide Testing Spectrum – Full coverage from static to dynamic testing allows the system to address a broad range of material characterization requirements.
Optimized Structural Design – A compact structure combined with a large loading space provides flexibility for diverse specimen geometries and environmental chamber integration.
Consequently, the entire biaxial fatigue testing machine platform can be combined with environmental accessories to complete multi‑physics coupled tests, enabling comprehensive material characterization under realistic service conditions.
What is planar biaxial testing?
In real‑world applications, most structures and components are subjected to loads acting in multiple directions simultaneously. To accurately simulate these service conditions, testing engineers must apply forces along more than one axis during the test. Unlike a standard uniaxial tensile test, the planar biaxial tensile test often requires not only axial loading of the specimen but also the application of torque. This, in turn, necessitates additional torque‑driving devices and drive mechanisms that pass through the crosshead. Consequently, the testing machine must precisely maintain the workpiece center in its original position while eliminating any risk of generating unwanted bending stresses.
To further investigate material behavior under biaxial tensile stress fields, cross‑shaped specimens have been widely adopted for such tests. Typically, these specimens feature a symmetrical cross geometry with four connection points, and the lengths of each arm are usually equal. As a result of this geometry, four independent test axes are required, and these additional axes are crucial for accurately reproducing constant stress ratios or any combination of stress paths. During the test, the cross‑shaped specimen is analyzed for stress at its central intersection point through bidirectional loading—for example, vertical and horizontal forces. This procedure, performed in accordance with the detailed guidelines of the ISO‑FDIS 16842 standard, is particularly well‑suited for stress analysis in metallic materials testing.
The demand for planar biaxial testing first emerged in the 1960s, driven by the rapid development of jet engines. Specifically, aerospace manufacturers required a deeper understanding of the stress states within aircraft structures, prompting the need to inspect both structural components and critical parts under multi‑axial loading conditions. Early on, another key application was analyzing the grain structure of metal flakes in automotive manufacturing, where biaxial stress data proved essential for process optimization.
As research demands evolved, the focus expanded beyond static tensile tests. In particular, researchers began to concentrate on dynamic testing, including fracture mechanics and fatigue crack propagation studies. Consequently, the role of the biaxial fatigue testing machine grew from a specialized research tool into an indispensable platform for characterizing material behavior under realistic, multi‑axial service conditions.
In China, Beihang University has been developing biaxial tensile testing machines since the early 1980s. Meanwhile, in the United States, MTS Systems established itself as the forerunner in this field. In the past decade, several domestic Chinese testing machine manufacturers have advanced the technology further, successfully developing and producing bidirectional testing machines. Notably, this progress also includes three‑axis testing machines, which are primarily used for compression testing of non‑metallic materials. As a result, the landscape of multi‑axial testing has evolved from specialized research equipment into a broader, commercially available category serving both metallic and non‑metallic material characterization.
The most challenging aspects of planar biaxial testing primarily revolve around three critical requirements: achieving precise center‑of‑mass control, ensuring correct system alignment, and implementing repeatable test procedures. To address these challenges, SINOTEST employs a precision centering device that provides accurate alignment adjustment between the fixtures. Furthermore, to minimize bending strain to the greatest extent possible, we utilize our self‑produced CMT hydrostatic bearing actuators, which are engineered for frictionless, high‑precision motion.
SINOTEST’s biaxial fatigue testing machines are fully compliant with GB/T 36024-2018 and related international test standards. Trusted by leading aerospace and automotive research institutions, our planar biaxial systems provide the rigorous multi‑axial validation required for advanced material characterization and high‑reliability applications.
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