The stress-strain curve is a vital indicator in material performance testing. It draws a curve that reflects the mechanical properties of the material by measuring the strain and stress of the stress material. The shape of this curve can tell us important information about the strength, toughness, yield point, and broken point of the material, which has great guiding significance for understanding the nature and application of the material. This article will focus on the characteristics of the stress-strain curve, different stages of the stress-strain curve, applications, and significance.
What is a stress-strain curve?
The stress-strain curve is the curve of the stress and strain relationship between the description of the material during the stress process. It can be used to measure the mechanical properties and deformation of materials. Depending on different materials and forces, the stress-strain curve can show different shapes.
What are the stages of the stress-strain curve?
Generally speaking, the stress-strain curve can be divided into five stages: elastic phase, yield phase, plastic stage, neck shrinkage, and breakthrough stage.
In the elastic phase, the strain of the material has a linear relationship with the increase in stress. When the stress is over, the material can be fully restored to the initial state without permanent deformation.
In the yield stage, as the stress continues to increase, the strain of the material starts to increase non-linearity. When a certain stress is reached, the material will cause plastic deformation, that is, the permanent strain that will not completely disappear in stress.
In the plasticity stage, the strain of materials continues to increase with the increase of stress, but the increase gradually slows down.
At the stage of neck shrinkage, the material will have local deformation, that is, the stress-concentrated area will occur, which will cause the fracture strength of the material to decrease.
In the breakthrough stage, the material cannot withstand the stress continues to increase, and eventually breaks.
The shape of the stress-strain curve of different materials may be different. Some materials may show a more complex curve, such as appearing in the strain hardening stage or remaining strain stage. At the same time, different external loading conditions and test methods may also produce different stress-strain curves.
The characteristics of the stress-strain curve:
The characteristics of the stress-strain curve are related to the nature of the material. Common materials such as steel, aluminum, copper, and other stress-strain curves are characterized as follows:
- Steel stress-strain curve Features: The stress-strain curve of the steel shows obvious linear elastic stages and plastic stages. When the stress reaches a certain value, the material begins to deform plastic humanity, and the increase in the strain is significantly accelerated. When the stress reaches a certain value, the material begins to enter the break, the strain increases sharply, and the break is in the end.
- The stress-strain curve characteristics of aluminum material: The stress-strain curve of aluminum materials is similar to steel, showing obvious linear elastic stages and plastic stages. The strain is larger than steel.
- The stress-strain curve characteristics of the copper material: The stress-strain curve of the copper material differs from that of steel and aluminum. Therefore, under the same stress, the strain of copper is larger than that of steel and aluminum.
Application and significance of stress-strain curve:
- Material characteristic assessment: Stress-strain curve can be used to evaluate the mechanical characteristics of the material, such as elastic modulus, yield strength, and broken strength. By observing the shape and characteristics of the curve, you can determine the performance of the toughness, brittleness, and ductility of the material.
- Material selection: According to the shape and characteristics of the stress-strain curve, you can choose the material suitable for specific applications. For example, in the absence of high strength and being able to withstand large deformation, select materials with better ductility.
- Engineering design: Stress-strain curve can help engineers optimize the design and ensure that the materials will not cause too much deformation or damage under the action of external forces. By analyzing the strength and stiffness of the curve, the appropriate size and material thickness of the structure can be determined.
- Forecast material failure: Stress-strain curve can predict whether the material will fail under different stress. When the stress exceeds the yield strength of the material, the curve generally decreases significantly, which indicates that the material is about to deform or damage.
- Material processing control: Analyzing and understanding the stress-strain curve, can help control the processing process of the material and ensure that the performance of the material after processing meets the requirements. For example, you can adjust the temperature and velocity rate in the process of processing according to the shape of the curve to obtain the expected material performance.
In a word, the significance and application of stress-strain curves are very extensive. It is one of the most important indicators in material performance testing. DMTC specializes in customizing various precision hardware parts for customers. We support the processing of all kinds of materials. In material selection, design, and machining control, the stress-strain curve provides an important reference and basis for our engineers.
