Mechanical strength refers to the maximum load that a material can bear per unit area when subjected to external forces. Generally expressed by bending (flexural) strength, tensile (tensile) strength, compressive strength, impact strength, etc. Mechanical structural strength is an engineering science and technology, and it is only meaningful and valuable for scientific theories and technologies that generally come from production and serve production.

Introduction

Mechanical strength refers to the ability of metal or non-metallic materials to resist deformation and damage under load. In addition to tensile strength, there are five types of bending strength, compressive strength, torsion strength, and shear strength. The most commonly used strength in engineering is tensile strength. There is a certain conversion relationship between tensile strength and other strengths, and other strength values ​​can be approximated by the tensile strength value of the material.

classification

Mechanical strength is divided into compressive strength, flexural strength, and tensile strength.

Compressive strength (compressive strength) code σbc refers to the strength limit when the external force is under pressure.

The flexural strength refers to the ultimate breaking stress when a material unit area is subjected to a bending moment.

test methods

There are several methods for measuring mechanical strength under static conditions in industry.

Compressive strength

Compressive strength is also called compressive strength or crushing strength. This is a common method for determining the compressive strength of a single carrier particle. It uses a device with a horizontal plate (top plate) that moves up and down. By continuously increasing the load of the sample particles until they rupture, record the crushing load. Usually the average value of at least a dozen tests is taken as the compressive strength.

Of course, the mechanism of crushing is still more complicated and affected by the shape of the platen and the ratio of the length to the diameter of the tablet. The compressive strength can be calculated by the following formula:

σD=P/F=4P/πd2=P/0.875d2

Where σD —— compressive strength, kgf/cm2;

P —— crushing load, kgf;

d ——The average diameter of the particle sample, cm.

The above calculation formula is only applicable to the vertical crushing test. At this time, the two flat and hard pressed tablets of the sample tablet are in contact with each other and crushed.

Another method for determining the compressive strength is to place the sample between two plates and apply pressure along the radial direction of the tablet, and calculate it with the following formula:

σm=P/L

Where σm —— lateral compressive strength, kgf/cm;

P —— crushing load, kgf;

L ——The length of the sample under load, cm.