Material Properties

With this page we’ll be able to define any materials and why certain materials are used for certain applications.
First of we’ll understand what is tensile test is. this is a fundamental test in material mechanic that  is performed by qualifying samples of materials until it reaches failure while measuring the force and displacement.  This provides a “stress vs strain curve diagram” which tells us a lot in the materials to force reaction.

Stress is the force divided by the cross area defined by the unit of Pascal. Usually stress is located in the Y-axis. While the change in length divided by the original length  is placed in X-axis and is called the strain.

Stress vs strain graph

As you can see as the graph rises the material begins to deform  the first initial region before it reaches the yield strength is called the elastic deformation which means it will still remain and return to its original form(eg. rubber band after stretching it out and returns to its original state) but if it goes beyond the yield strength as additional force is applied it will not return to its original state anymore in other words there will be permanent deformation. Moreover, if the strength continuous to rise until it reaches its ultimate strength (the ultimate force the material can handle) it will reach its fracture.

Young’s modulus is defined how stiff a material is. This is obtained through the slope of the linear region. the stiffer the material is the stiff it is. For example a carbon fiber may look very stiff but for a rubber band a little low . This young’s modulus is mostly used in Engineering as this is used to predict the sagging point of steels and used to compute for bridges, roads and mostly buildings.

So using the diagram, when it’t diagram shows a small deformation of materials that means it is ductile. Ductile materials can absorbed a lot without deformation. Typical example is the spring materials. Opposite to ductile is brittle which is easily deformed when force is applied example of this is glass.

Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change when compression force is applied.