RMiller77
Mechanical
- Oct 15, 2008
- 4
Spring design and treatment is not my area of expertise, so the information found on this forum is much appreciated. I do understand some things about vibrations.
I am designing a patented prototype machine whose main component is a very large spring set capable of storing a great deal of energy through deflection. The spring oscillates about its neutral position and processes material with its motion.
The simple question is how to obtain the best set of bars to construct a spring set? The preferred size is a rectangular bar about 2” x 6” x 60” (50 x 150 x 1500 mm) long. Twenty-four of these bars may be needed, but a smaller number is possible.
The bar is simply supported on a 50” (1300 mm) span with a large mass mounted on the spring at two locations equal in distance and mass about the center of the span. The mass is excited in a controlled manner to oscillate the spring, displacing the weak axis (2” dimension) horizontally by 0.5” (12 mm). The bar bends about the vertical axis parallel with the 6” dimension. The spring oscillates 1” (25 mm) peak to peak on each side of its neutral position about 30 times a second.
The bending stresses on the bar are under 65 ksi (450 MPa). The number of cycles will exceed 10^8.
The bending stresses can be lowered by increasing the thickness and length of the bar. This maintains energy storage capacity while reducing stresses. The trade-off is more steel is required to accomplish the same work.
The machine will weigh less if stronger springs are used, thus there is an impetus for buying better steel. The machine will be more efficient if the material has a low loss coefficient.
The major suppliers stock bars that may be adequate for the prototype, but since these springs are the heart of the machine, a careful selection is desired. The design to use a common shape for the prototype spring was intentional. Commercial units will have better spring design than the prototype.
This site has discussed various spring materials that greatly exceed the cataloged performance of the spring materials I have found. How do I obtain these processed materials in a common shape in what is likely a relatively small batch (2.5 tons)?
There is a sketch of a concept machine at the website listed below.
Thank you for all the information shared here. It is good stuff.
I am designing a patented prototype machine whose main component is a very large spring set capable of storing a great deal of energy through deflection. The spring oscillates about its neutral position and processes material with its motion.
The simple question is how to obtain the best set of bars to construct a spring set? The preferred size is a rectangular bar about 2” x 6” x 60” (50 x 150 x 1500 mm) long. Twenty-four of these bars may be needed, but a smaller number is possible.
The bar is simply supported on a 50” (1300 mm) span with a large mass mounted on the spring at two locations equal in distance and mass about the center of the span. The mass is excited in a controlled manner to oscillate the spring, displacing the weak axis (2” dimension) horizontally by 0.5” (12 mm). The bar bends about the vertical axis parallel with the 6” dimension. The spring oscillates 1” (25 mm) peak to peak on each side of its neutral position about 30 times a second.
The bending stresses on the bar are under 65 ksi (450 MPa). The number of cycles will exceed 10^8.
The bending stresses can be lowered by increasing the thickness and length of the bar. This maintains energy storage capacity while reducing stresses. The trade-off is more steel is required to accomplish the same work.
The machine will weigh less if stronger springs are used, thus there is an impetus for buying better steel. The machine will be more efficient if the material has a low loss coefficient.
The major suppliers stock bars that may be adequate for the prototype, but since these springs are the heart of the machine, a careful selection is desired. The design to use a common shape for the prototype spring was intentional. Commercial units will have better spring design than the prototype.
This site has discussed various spring materials that greatly exceed the cataloged performance of the spring materials I have found. How do I obtain these processed materials in a common shape in what is likely a relatively small batch (2.5 tons)?
There is a sketch of a concept machine at the website listed below.
Thank you for all the information shared here. It is good stuff.
