desire to fabricate a frost tooth for my excavator have questions on the steel

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This winter I plan on fabricating a frost tooth for my  CAT E120B excavator.The steel I can acquire at a reasonable price, 48 inch long 10 inch wide 3 inch thick for $350.00. thats for the shank.It is A36 steelminimum tensile strength (ksi) 58-80minimal yield strength (0.2%, ksi) 36hardness B76I would hard face the sides half way up and the front edge with three or four lines.My question is what do the above numbers referencing the steel mean?The excavator has a maximum stick force of 14,550 lbsa maximum bucket force of 17,416 lbsWould the A36 steel hold up to the excavator or fail, not my welds fail the steel fail.
Reply:http://weldingweb.com/vbb/showthread.php?t=47867
Reply:Min. tensile strength refers to the strength of the steel in a tension situation. Minimum yeild strength is the number to use as it refers to when the steel will start to stretch or permanently deform. So if the steel is rated at 36 ksi yeild, that means a 1" square bar can hold 36,000 lbs in tension before it will begin to stretch.I AM NOT AN ENGINEER.That said, using some online calculators. I found that a 10x3 bar of a36 steel cantilevered 48" with 20,000 lb load will deflect 0.099" and have a maximum stress of 6500 psi. I think it will be more than strong enough, it all depends on the connection.Ian TannerKawasaki KX450 and many other fine tools
Reply:Fortyonethirty has it right for the simplest case.  But you also need to consider torsion(twisting) or shear loads to ensure that your frost tooth won't break.  For example, an operator sinks the shank into the ground and then tries to pivot the equipment, or hooks a very large rock or buried piece of steel or concrete and(accidentally) tries to pull it sideways and up and out of the ground.Here's a link to a table that relates shear strength to yield strength, as a general guidelinehttp://www.roymech.co.uk/Useful_Tabl...ar_tensile.htmShear strength for wrought steel, the closest material to your A36 structural steel bar, is about 60% of tensile yield strength.  So your frost tooth is much more likely to fail in shear than in tension or compression.  Couple this with the fact that the forces applied to the tooth if you're dragging it through the ground are almost all shear loads.It's hard to estimate the forces your equipment could generate in these situations, so it's tough to say for certain how your attachement will fare.  Best advice is to copy a design you know works well for shape.  Ask the manufacturer what kind of steel they used to make the tool you know works.  Barring that you just need to build it, use it, break it, and then re build it better based on how/why it broke.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Send me a drawing and how you are going to hook up to excavator I will do some calculations.I am an engineer, teach at Michigan Tech University, also a PE.  I teach statics, machine design and do lots with fluids. Mark