The Failure Theories

We all know that failure is a part of life. But what do we do when it comes to our businesses? Do we give up, or do we learn from our failures and try again? In this blog post, we will discuss the different theories of failure and how you can learn from them. We will also provide some tips on how to overcome failure in your business. So read on and find out more about the failure theories that you need to know.

What are Failure Theories In Engineering?

Failure theories help engineers and designers predict how a structure will fail under various loads. Several types of failure theory can be applied to different materials and situations, but the most popular is ductile versus brittle fracture theory.

The type of material used in construction determines what kind of failure we may expect when it comes time for that material to fail.

Elastic behaviour is reversible, which means stress will remain constant if the load remains unchanged. Plastic deformation occurs when there is a permanent change in shape due to applied force beyond what the material can handle. Also, plastic behaviour usually causes large deformations before failure takes place with a little warning prior (a ductile fracture). Brittle behaviour results in a sudden and rapid failure with little or no deformation.

Some Theories of Failure in Machine Design

Maximum Shear Stress Theory: The maximum shear stress theory postulates that when the material is in a state of pure tension and pure compression, then failure will occur at stresses equal to one half the yield strength. This theory was first proposed by Rankine in 1857.

Explanation: In the case of tension, failure will occur when the maximum shear stress is equal to one half the yield strength. Likewise, in compression, failure will occur at a stress level that is also equal to one half the yield strength.

Strength Reduction Factor: The strength reduction factor theory was proposed by William Rankine in 1857 and postulates that ductile materials break when the maximum shear stress reaches a value equal to one half of the yield strength divided by a safety factor known as ‘K’.

Explanation: The lower the value of K, the higher will be its efficiency. High values of K are more efficient than low values.

Maximum Strain Energy Theory: The maximum strain energy theory, also proposed by William Rankine in 1857, states that materials break when the total strain energy reaches a value equal to the yield strength multiplied by a safety factor known as ‘K’.

Explanation: Just like the strength reduction factor theory, this one is also based on the concept of safety factors. Here, the higher the value of K, the more efficient will be its performance and vice versa.

Maximum Principal Stress Theory: According to this theory, failure occurs when either principal stress reaches a value equal to the yield strength divided by a safety factor known as ‘K’ or when the maximum shear stress reaches a value equal to one half of the yield strength multiplied by a safety factor known as ‘K’.

Explanation: This theory is based on the assumption that either principal stress can cause failure. It also takes into account the safety factor.

Maximum Principal Strain Theory: The maximum principal strain theory, proposed by Mohr in 1869 and Strains in 1902, states that failure will occur when either of the two principal strains reaches a value equal to one half of the yield strength multiplied by an efficiency factor known as ‘K’.

Explanation: This theory is similar to the maximum principal stress theory, but considers only one of the two principal strains. It also takes into account the safety factor.

Maximum Displacement Theory: The maximum displacement theory, proposed by Tresca in 1863, states that failure will occur when the maximum shear stress reaches a value equal to one half of the yield strength multiplied by a safety factor known as ‘K’.

Explanation: This theory is based on the concept of maximum displacement and considers only shear stress. It also takes into account the safety factor.

Conclusion

The failure theories discussed in this article are important to know about. Each theory has its unique perspective on why things go wrong, and understanding these theories can help you avoid or recover from failure.

It’s also worth noting that there is no one-size-fits-all approach to failure. What might work for one person may not work for another, and what works in one situation may not work in another. So it’s important to be flexible and adaptable and to keep an open mind when it comes to failure.