1、 Materials Science Classification Keywords Popular Explanation

1. Stress

When a material cannot produce displacement under external force, its geometric shape and size will change, and this deformation is called strain. When a material undergoes deformation, a reaction force of equal magnitude but opposite direction is generated inside to resist external forces, which is called stress.

2. Elasticity

After being subjected to external forces, materials will undergo deformation, and the ability to restore their original state by removing the external force is called the elasticity of the material.

Elastic deformation: Although deformed, it returns to its original state after removing stress.

Most wood and insulated air have good elasticity.

3. Rigid

Generally refers to the ability of a material not to deform under external forces.

The smaller the elastic deformation under external force, the stronger the rigidity of the material.

Wood is a material with weak rigidity, but the structural rigidity formed by different wood varieties, cutting directions, and splicing methods varies greatly.

4. Cedar wood

The wood texture is straight, the structure is uniform, without warping or cracking, the wood density is 0.39, the average number of annual rings per centimeter is 3.0, the latewood rate is 22.0%, the shrinkage coefficient (volume) is 0.386, the ultimate compressive strength along the grain is 358 kg/square centimeter, the ultimate static bending strength is 661 kg/square centimeter, and the end face strength is 285 kg/square centimeter. The material is light and tough, with moderate strength and a high quality factor. It has a fragrant aroma, contains "cedar brain" in the wood, is resistant to insects and decay, and is easy to process.

The cedar used for violin making has higher requirements.

5. Maple wood

The white wood of the hard maple is milky white with a brownish red hue, and the heartwood ranges from light brownish red to deep brownish red. Both white wood and heartwood may contain wood pulp spots. This type of wood has dense and fine grain, usually straight wood grain, but can also appear curved, arched, and bird eye shaped wood grain; The color of maple wood varies greatly depending on its origin. The white wood of soft maple is gray white in color, sometimes with darker wood pulp spots. Its heartwood color ranges from light brownish red to dark brownish red. This type of wood is usually straight wood grain. Physical characteristics: Hard maple wood is hard, heavy, and has good strength performance. It has particularly high abrasion and wear resistance, as well as good resistance to steam bending. The hardness of soft maple is about 25% less than that of hard maple, with moderate bending and fracture strength, low rigidity and seismic strength, and good resistance to steam bending.