# How to Calculate Yield Strength of a Spring

How to Calculate Yield Strength of a Spring

Mechanical spring action has been put to use by humans since the invention of crossbow. Although theoretical knowledge of yield strength was quite rudimentary, importance of its practicality was understood. Yield strength of a spring is defined as the stress at which the spring starts deforming plastically, i.e. stress beyond which the cannabis news spring stops returning to initial position. It is also known as elastic limit or yield point. This article discusses the methods of calculating the yield strength of the most commonly used mechanical springs. An accurate method to calculate the strength is subjecting the spring to an incremental stress change and simultaneously looking for the point of no return. Nevertheless, this method of calculation of yield strength for limited production springs is not viable. Hence, in such cases the yield strength is deduced by physical characteristics of the material and extrapolation. Most commonly used mechanical springs are helical springs, which are then classified based on the principle of the spring action, as follows:

Extension Coil Springs

Compression Coil Springs

Torsion Coil Springs

The calculation of the yield strength is important for calculation of safe loading factors and to ensure a long lasting use of the springs.

Calculation of yield strength of extension coil springs:

Extension coil springs are designed to exhibit elastic properties when stretched across its length, i.e. they are used to hold the attached components together. A hook to secure their initial position usually characterizes these springs. Most common examples of these type of springs are the trampolines and weighing scales. To calculate the yield strength of this type of spring, the control sample of a spring is subjected to partial extension by applying force in small steps such that spring is expanded by one percent of the spring length. By keeping the expansion of spring constant, the strain is kept constant, assisting in easier extrapolation of yield point. The force is applied in the form of weights, which are converted into their relevant force equivalents by taking into account the gravitational pull and the horizontal and vertical components of the force. After exertion of the known force, the force is removed to verify the presence of elastic properties in the spring. The point at which a complete absence of elastic properties is observed is noted and multiplied with the safety factor. The value is an effective indicator of safe loading and yield strength. Further experimentation to determine exact yield strength is done by subjecting a similar spring to strain in a precise manner between the points of presence and absence of elasticity.

Calculation of yield strength of compression coil springs: