Calculation formula: f=Fmax/A

Three-point loading f=FL/bh² Single-point loading f=3FL/2bh²

When the cross-sections of the specimens are the same, the measured strength value of the short specimen is higher than that of the long specimen. The measured compressive strength values ​​of small specimens are higher than those of large specimens

When the pressure areas are the same, the entire cube specimen is limited by the hoop effect. The uniaxial compressive strength of cubic specimens is higher than that of prismatic specimens.

In the concrete compressive strength test, the compressive strength test value of the 150mm cube specimen is higher than the compressive strength test value of the 200mm cube specimen.

×When the test loading speed is faster, the measured strength value of the material is higher, otherwise it is lower. Therefore, a faster loading speed should be used as much as possible during the test

×Measure the strength of the material in the dry state, because the material has the highest strength in the dry state

The higher the moisture content, the more the strength decreases.

The surface of the specimen is uneven, with edges and corners missing, or the specimen is in smooth contact with the test device. It will lead to stress concentration, which will make the strength measurement value lower.

Definition: The property of a material that is deformed under the action of an external force and can completely restore its original shape after the external force is removed.

Index: Elastic modulus--E=σ/ε, the larger E, the less likely it is to deform.

Definition: A material deforms under the action of external force. After the external force is removed, it can still maintain the deformed shape and size without cracks.

The compressive strength, tensile strength and bending strength of plastic materials such as steel are roughly equal, with the lowest shear resistance. They can withstand tension, compression and bending moments.

Definition: When the external force reaches the limit, the material suddenly breaks, and there is no obvious plastic deformation before the damage rather than no deformation.

Mechanical characteristics: Compressive strength is much higher than tensile and bending resistance. i.e. often used in areas under pressure

Definition: Under impact and vibration loads, The material can absorb a large amount of energy and can also deform to a certain extent without damaging it.

The phenomenon that the deformation of solid materials gradually increases with time under the action of external force.

When a material is under load and the resulting deformation cannot develop due to constraints, the stress will gradually decrease over time. (It is caused by the gradual increase in plastic deformation of the material, the gradual decrease in elastic deformation, and the "total deformation remains unchanged")