How To Calculate Yield Strength Of A Cantilever Springs |
Posted: May 29, 2017 |
Mechanical cantilever springs 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 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: This spring type is also a type of the helical type cantilever springs design. In contrast to the working of extension coil springs, these springs are designed to exhibit elastic properties when they are compressed, i.e. these springs are used for keeping the component attached to it apart. One of the most visible uses of this type springs are shock absorbers in vehicles. The calculation of yield strength in compression type springs is to be done a little differently from the expansion springs. Unlike expansion springs the possible maximum range of operation is visually conceivable. In this case, the force is applied in steps of one hundredth of the possible range of action. Calculation of yield strength of torsion coil springs: Unlike the helical spring types mentioned above, torsion springs employ the elasticity in the axial component of the spring to exhibit elastic action. This type of spring is used in clips and mousetraps. The yield strength calculation is done as similarly as in compression springs. The range of operation is limited and the force applied in a similar fashion as done in compression springs.
This type of calculation is can be extended to other types of springs by assessing the range of their operation. For more information, or to locate and contact a supplier of compression, extension, and torsion springs, please check out Zycon's comprehensive list of spring manufacturers. Ron Bargman, president of Zycon, has been fascinated and involved with the engineering and manufacturing processes required to turn ideas into products for over 30 years. Mr. Bargman is a regular contributor of manufacturing theme articles, and his rich industry history provides insight into manufacturing and engineering events and changes that are timely, poignant, and relevant. Through Zycon, he is able to transfer his passion for the industry by assisting engineers, designers and inventors find the services, parts and components that they need to succeed.
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