Maximum Stress Principle

The maximum stress principle is usually known as Rankine principle. In accordance with this principle, failure happens if the highest basic principle stress within a system (S₁) is actually higher when compared with the highest tensile stress principle at yield within a specimen put through to uniaxial tension experiment.

Uniaxial tension experiment can be essentially the most popular experiment performed regarding to every material of construction. The tensile stress within a consistent cross-section specimen will be described as yield stress (Sy) at yield with regard to every material as well as usually available. In uniaxial experiment, the utilized load provides increase solely to axial stress (S_L) and also circumferential stress (S_C), radial stress (S_R) and also shear stresses tend to be omitted.

Furthermore, the following equation below can be taken from uniaxial experiment:

S₁ = S_Y                        S₂ = 0              S₃ = 0

S_L = S_Y            S_H = 0              S_R = 0

The highest tensile stress principle at yield is so equivalent to the typically described yield stress. The Rankine principle hence only states that failure happens if the maximum stress principle in a system (S₁) is much more when compared with the yield stress on the material (Sy). The maximum stress principle in the system must be determined as before. This will be exciting to examine the implication of that principle upon the event if a pipe is put through to internal pressure.

According to the membrane principle pertaining to design pressure of pipe, provided that the circumferential stress is a smaller amount compared to the yield stress from the material construction, the design will be secure. That can be recognized that circumferential stress (S_C) caused by external pressure is two times the axial stress (S_L).

The stresses in the pipe depending on the previously assigned formulation could be as following below:

S₁ = (S_L + S_C)/2 + [{(S_L - S_C)/2}² + τ²]^0.5

     = S_L

S₁ = (S_L + S_C)/2 - [{(S_L - S_C)/2}² + τ²]^0.5

     = S_H

The maximum stress principle within the following scenario is S₂ (=S_C). The Rankine principle and the design considerations used in the membrane principle will be consequently appropriate. This principle is commonly applied for calculation of strain thickness for piping layout and pressure vessels employs Rankine principle as considerations to get failure.