Introduction to Fatigue Testing Machine

Fatigue testing machine is a machine mainly used for testing the fatigue performance of metals and their alloys under tensile, compressive, or alternating tensile and compressive loads at room temperature.

The characteristic of fatigue testing machine is that it can achieve high load, high frequency, and low consumption, thereby shortening the testing time and reducing the testing cost.

Fatigue testing machines are used to determine the fatigue characteristics, fatigue life, pre fabricated cracks, and crack propagation tests of metals, alloy materials, and their components (such as operating joints, fasteners, spiral moving parts, etc.) under tensile, compressive, or alternating tensile and compressive loads at room temperature. After being equipped with corresponding test fixtures, the high-frequency fatigue testing machine can perform three-point bending test, four point bending test, thin plate tensile test, thick plate tensile test, reinforced steel bar tensile test, chain tensile test, fastener test, connecting rod test, torsional fatigue test, bending torsional composite fatigue test, interactive bending fatigue test, CT test, CCT test, gear fatigue test, etc. under sinusoidal load.

2 Experimental methods

Fatigue test refers to the method of measuring the fatigue limit of metal materials under symmetric cycling by measuring their σ -1 through metal material experiments, drawing the S-N curve of the material, and observing the fatigue failure phenomenon and fracture characteristics. Testing equipment generally includes fatigue testing machines and vernier calipers.

Under sufficiently large alternating stress, micro cracks may occur in areas such as sudden changes in the shape, surface scratches, or internal defects of metal components due to significant stress concentration. Scattered microscopic cracks will form macroscopic cracks through aggregation and communication. The macroscopic cracks that have already formed gradually and slowly propagate, and the cross-section of the component gradually weakens. When a certain limit is reached, the component will suddenly fracture. The above-mentioned failure phenomenon of metals caused by alternating stress is called metal fatigue. Materials with good plastic properties under static load often experience sudden fracture when subjected to alternating stress without significant plastic deformation below the yield limit. The fatigue fracture surface is clearly divided into two regions: a relatively smooth crack propagation zone and a relatively rough fracture zone. After the formation of a crack, alternating stress causes the two sides of the crack to open and close intermittently, squeezing and repeatedly grinding each other. This is how the smooth area is formed. The interruption and variation of load leave multiple crack front lines in the smooth area. As for the rough fracture zone, it is formed by the sudden rupture at the end. Statistical data shows that about 70% of mechanical component failures are caused by fatigue, and the majority of accidents caused are catastrophic. Therefore, it is of practical significance to study the fatigue resistance of metal materials through experiments.

3 uses

The fatigue testing machine can perform dynamic and static mechanical performance tests on various metals, non metals, and composite materials, including tension, compression, bending, shear, fatigue, crack propagation, fracture, etc. It is particularly suitable for high-temperature strain control testing when equipped with a high-temperature device. It is an advanced testing equipment required for scientific research, production, arbitration and inspection.