Mechanical properties of metals:If you are a design engineer from the field of Mechanical Engineering then you should has to know about Mechanical properties of metals so that those can be taken into consideration while designing.because you are the one, who can know about the need and according to that need, what type of material can be taken as dependent on you.
That’s the basic consideration every design engineer must follow in picking up on the best material depending upon the Mechanical properties of metals.
Considering this fact, I will be explaining about 31 Mechanical properties of metals that every Mechanical engineer must know in this article in a detailed manner. Read this article completely so that it can be used in Interviews also.
Concepts discussed are as follows:
1.Mechanical Properties of Metals
2.Material Selection with Flowcharts, Phases in Design, Spring back, Design Thinking
31 Mechanical properties of metals:
The 31 Mechanical properties of metals that every Mechanical engineer must know was explained below.
The ability of a material that can withstand to Mechanical load is called Strength of that particular material.
• A strength of the material depends upon the directions in which it is loaded
• Ex: Tensile Test
• From Tensile Test, we get Tensile Strength, ductility, fracture toughness, resilience, yield stress, etc.
The ability of a material that can undergo plastic deformation before failure is called Ductility.
Ductility (D)= % of Elongation in length or % of Reduction in Cross-section at breaking point.
Note: Ductility is always reported in % of elongation in length but not in % of the reduction in c/s area because a reduction in c/s section area is small and difficult to measure during testing.
% of the elongation at different Temperatures:
If you can see the % of elongation of a metal w.r.t.Low temperature(L.T),Room temperature(R.T) and High temperature(H.T) was
The ability of a material that can absorb energy at the time of failure against fracture is called Fracture Toughness.
• By calculating the area under stress v/s strain curve up to the failure point, the fracture toughness of the material is determined.
• A material possesses high fracture toughness means it has a higher capacity to absorb more strain energy against failure.
• A brittle material possess lower the fracture toughness(F.T) compared to a ductile material because of the area under the curve
A Ductile > A Brittle
F.T Ductile > F.T Brittle
Considering an area of Stress v/s Strain curve at different temperatures is noted as follows.
A H.T > A R.T > A L.T
F.T H.T > F.TR.T > F.T L.T
If the material is tested at high temperature, the displacement of atomic planes is easy, implies it can produce more plastic strain, implies area under the curve will be more, implies Fracture Toughness is high.
The resistance offered by the material against mechanical deformation is called hardness.
The ability of a material that can withstand mechanical load without plastic deformation is called Brittleness.
The ability of a material that can resist mechanical deformation under stress is called stiffness.
Time v/s Strain behavior of a material under Constant mechanical load is called Creep.
Stress v/s no. of load cycles of the behavior of metal under changing mechanical load with Time is called as Fatigue.
• Fatigue is a danger than Creep
• Therefore, more FOS is given for Fatigue loading.
It is a capability of being extended or shaped by beating with a hammer or by the external pressure of rollers so that the output is in the form of thin sheets called as Malleability.
The quality of being easily shaped or molded called Plasticity.
The ability of an object or material to resume or regain its normal shape or original shape after being stretched or compressed called Elasticity.
It is the state of being strong enough in order to withstand adverse conditions or rough handling called Toughness.
It is also defined as the Area under P.(Delta) curve up to Failure is called as Toughness.
The resistance of a material to breaking under tension called Tensile Strength.
The resistance of a material to breaking under Compression is called Compressive strength.
The ability of a material that can absorb energy without undergoing any shape change called Resilience.
• By calculating the area under Stress v/s Strain curve up to an elastic point, resilience(elastic resilience) of the material will be determined.
These are the 15 Mechanical properties of metals that are explained in a detailed manner and the rest are below along with material selection with flowcharts.
The hardenability of a metal alloy is the depth up to which a material is hardened after putting through a heat treatment process called hardenability.
It is a process of removing the layer from the surface of the workpiece so as to get a good surface finish on the outer surface of the material called Machinability.
In the most general case, good machinability means that material is cut with good surface finish, long tool life, low force, power requirements, and low cost.
When a material is loaded with a force, it produces stress which then causes the material to deform.
Stress is defined as “force per unit area” – the ratio of applied force F to the cross-section area is called stress.
Young’s modulus is the ability of a material to withstand changes in length when under lengthwise tension or compression.
- It is denoted by E.
- It is also defined as the ratio of stress to strain.
It is a change in the shape of a material at low stress that is recoverable after the stress is removed called as Elastic deformation of a material.
A temporary shape change that is self-reversing after the force is removed, so that the object returns to its original shape called as the elastic deformation
Plastic deformation is a process in which permanent deformation is caused by a sufficient load. It produces a permanent change in the shape or size of a solid body without fracture, resulting from the application of sustained stress beyond the elastic limit.
After plastic deformation, no elastic recovery takes place.
22.The factor of safety:
It is the load-carrying capacity of a system beyond the expected or actual loads.
the factor of safety is how much stronger the system is that it usually needs to be for an intended load.
The factor of safety is different for brittle and ductile materials.
It is the measure of the ability of an elastomer to return to its original shape when a compression load or external load is removed called Elastic Recovery.
Engineering stress is the applied load divided by the original cross-sectional area of a material. It is also called nominal stress.
True stress is the applied load divided by the actual cross-sectional area (the changing area with respect to time) of the specimen at that load.
Poisson’s ratio is the ratio of transverse contraction strain or Lateral strain to the longitudinal extension strain(Linear strain).
It is the relative change in the volume of a body produced by a unit tensile or compressive stress acting uniformly over its surface.
It is also known as shear modulus
It is defined as the ratio of shear stress to the shear strain.
It is defined as the ratio of change in dimension to its original dimensions called a strain.
- It is denoted by “Ɛ”
- It is a Dimensionless parameter
- Strains the response of a system to applied stress.
Now lets discuss the types of strains in a detailed way…
3 Types of Strain every Engineer must know:
When you are going for any Interview, every recruiter will ask some questions and out of those questions, this question was also on the list. As we know about only one strain i.e.change in dimension to its original dimension but, when the recruiter asks about the types of strain, we will be looking here and there.
Therefore, In this article, I will be explaining about 3 Types of strain along with their representation.
3 Types of Strain every Engineer must know:
The 3 types of strain are as follows.
The detailed explanation of all these Types of Strain is presented below.
- It is defined as the ratio of change in dimension to its original dimension.
- It is due to the normal forces and it is represented by e or ε.
- It is a dimensionless parameter.
If we consider the dimension as Length then Change in length to its original length is the Normal strain and it is represented below.
Let “L” be the Length of the component and “dL” will be the Change in Length of the component then the representation of the Normal strain is
|e or ε = dL/L|
- It is defined as the angular distortion between any two mutually perpendicular planes in radian’s is the shear strain.
- It is due to shear force or tangential force acting on a specimen.
- It is represented by gamma (γ).
Consider a component which is subjected to equal and opposite forces on either face (AB&CD) and one end of the face(AB) is fixed and the other end(DC) is kept free. Due to the application of force on one of the face, the component gets distorted through an angle of φ to the shape ABC’D’.
Now Shear strain or deformation per unit length is of the component is = CC’ / CD = CC’ / BC = * radian
- It is defined as the ratio of change in volume to its original volume.
- It is due to the normal forces only.
- It is a dimensionless parameter.
This means that the volumetric strain of a deformed body is the sum of the linear strains in three mutually perpendicular directions.
- Due to normal forces, there will be dimensional and volumetric changes.
- Due to shear, there will be distortion in shape without a change in volume.
- Stress depends on strain.strain is an independent parameter and stress depends on strain.
This is the complete explanation of all the 3 types of strain in a detailed manner. If you have any doubts, then you can ask us from the comments section.
This is the detailed explanation of the Mechanical properties of metals. Hope, this information is helpful to you.
Now we can discuss…
Material Selection with Flowcharts, Phases in Design, Spring back, Design Thinking:
Material selection plays a vital role in the field of design. In this article, I will be explaining how to do the Material Selection in Mechanical Design with the help of Flowcharts along with the design thinking process with 6 phases of design. Apart from that, I will explain about Spring back in design and Determination of Shear center in the sections.
Flowcharts include design tools, Market Requirements, Material data needs, etc. The detailed explanation about the flowcharts for material selection in Mechanical design is as follows.
Flowchart for Material Selection in Mechanical Design:
The flowchart for Material Selection includes 3 steps which are as follows.
3.Material Data needs
These three combined together and produce Product Specification.
- Function Modelling
- Viability studies
- Approximate Analysis
- Geometric Modelling
- Simulations method
- Cost Modelling
- Component Modelling
- Finite Element Modelling
- DFM and DFA.
3.Material Data Needs:
- Data for all materials, low precision, and detail.
- Data for a subset of materials with higher precision and detail.
- Data for one material with highest precision and detail.
The connection between these 3 steps as shown in the above figure.
Now, I will be explaining about the Design Thinking process along with the 6 Phases in Design.
Design Thinking-6 Phases in Design:
- Recognition of need
- Definition of problem
- Analysis & Optimization
Explanation of 6 Phases in Design:
1.Recognition of need:
The recognition of the need must be checked during designing or planning a program.
One of the examples for Recognition of need is the transportation system in which different aspects are to be considered and are as follows.
Ex: Transportation Equipment
- Faster transportation system
- The transportation system should be Economical i.e initial cost and running cost.
- There should be lesser environmental pollution due to transportation.
2.Definition of the Problem:
All the specifications are to be specified while defining a problem like What is the output for this problem etc.
3.Synthesis, Analysis, and Optimization:
- Firstly, Synthesis is to be done and later Analysis is to be made on the required component so as to analyze the deformations, stresses, strains, etc present in the component.
- If the stress in the structure(which we had defined in the problem)is above the yield point, then it is a case of failure and we have to optimize it so that there should be no failure.
- If the stress induced in the structure is less than the yield point of the material then it is safe. There is no need to further optimize.
Now let’s enter into our 3rd concept i.e. Spring back in design.
What is Spring Back in Design?
At the end of every metalworking operation, when the pressure on the metal is released, then there exists an elastic recovery by the material and the total deformation will get reduced a little called as Spring back in design.
- Spring back depends on yield point strength of the metal.
- Compensation can be made on spring back.
To compensate the spring back, the cold deformation must always be carried beyond the desired limit by an amount equal to spring back.
Let’s enter into our last concept i.e. location of shear center in sections.
How to determine the location of the shear center in the sections?
The shear center is also known as torsional axis, is an imaginary point on a section, where a shear force can be applied without inducing any torsion. In general, the shear center is not the centroid. In this article, I am going to explain how to determine the location of the shear center in the sections in a detailed manner.
The shear center is defined as the point on the beam section where the load is applied and no twisting moment is produced.
- At the shear center, resultant of the internal forces passes.
- For symmetrical sections, the shear center is the center of gravity for those sections.
- We can place the loads at the shear center where there is a sliding problem in those sections.
- What is Just in Time Manufacturing and Just in time Stock Replenishment?
- CAPP: Generative, Variant & Retrieval CAPP-Detailed
Hope this article is helpful to you. If any Mechanical properties of metals are missing, please fill those from the comments section so that we can make an update of this article.