Determing the point at which a weld will fail..details inside
Determing the point at which a weld will fail..details inside
(OP)
OK so here is the situation. I have a part that has a 36" long piece of box tubing welded on both sides to a frame (box tubing dimensions: 1" x 1"). I need to prove with equations that this device can support a 200lb load. Im assuming that welds will fail before the beam it self fails so I am looking for an equation to solve the strength of the weld. Then use a factor of safety to take into account the high probablity that the weld is not perfect.
The box tubing is welded to the frame on all four sides. The width of the weld is ~0.25" and are the length of the tubing (in this case 1").
For a better idea of what I am looking at. This part is a frame around a truck loading door. The loading dock is no longer used so they put this part over the opening for fall protection. Its approximatly 8' tall and about 6' wide. There are 6 of these box tubings that are equally spaced down the frame. The frame is welded in 6 spots (welds are about 2-3" long). For the worse case scenerio Im going to assume the load is placed all on one beam and in the center of that beam. I'm also assuming that the welds at the end of the box tubing will break before the 6 welds that hold the overall frame to the docks walls.
Any help would be appreciated. Ask any questions if you need something clarified. I think a picture would help describe what I'm going after, but unfortunatly at work I can't upload them.
The box tubing is welded to the frame on all four sides. The width of the weld is ~0.25" and are the length of the tubing (in this case 1").
For a better idea of what I am looking at. This part is a frame around a truck loading door. The loading dock is no longer used so they put this part over the opening for fall protection. Its approximatly 8' tall and about 6' wide. There are 6 of these box tubings that are equally spaced down the frame. The frame is welded in 6 spots (welds are about 2-3" long). For the worse case scenerio Im going to assume the load is placed all on one beam and in the center of that beam. I'm also assuming that the welds at the end of the box tubing will break before the 6 welds that hold the overall frame to the docks walls.
Any help would be appreciated. Ask any questions if you need something clarified. I think a picture would help describe what I'm going after, but unfortunatly at work I can't upload them.





RE: Determing the point at which a weld will fail..details inside
RE: Determing the point at which a weld will fail..details inside
RE: Determing the point at which a weld will fail..details inside
BTW I said butt weld yesterday, but its a fillet weld. Sorry for the confusion.
I found this site taht has some information, but it looks like it will tell me a shear stress. Does anyone have a table of standards for different types of welds (as far as max shear stress is concerned).
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RE: Determing the point at which a weld will fail..details inside
I am not clear exactly what this tube connection is for but you do mention it is for fall protection. Do you mean an anchor and lifeline system or similar? If so it would have to hold alot more than 200 lbs and you should have a good look at your local safety codes and regulations. You may even need it certified by a professional engineer.
RE: Determing the point at which a weld will fail..details inside
They claim, “Welds will provide a weld stress analysis for almost any weld shape that you can imagine.”
The program works for a 30 day trial before being disabled.
RE: Determing the point at which a weld will fail..details inside
have a look at this site it may help:-
http://ww
regards
desertfox
RE: Determing the point at which a weld will fail..details inside
I am an intern so this project was given to me. The saftey person here just wants me to prove it can withstand a 200lb force. I have already used my information from Mechanics of materials to find the deflection in the beam, but now I just want to make sure the welds can hold.
I will check out those sites. Thanks. Any other help is welcomed as well.
RE: Determing the point at which a weld will fail..details inside
If you check out this website (http://www.yakpol.net) they have a fully functional demo weld analysis spreadsheet which also explains the theory and shows the details of the calculations. It should be able to solve your problem.
As I mentioned earlier since you don't know what electrode was used you will have to make some assumptions. However 200 lbs isn't that much weight for a weld to hold, could you do a load test to say 200 lbs plus some additional weight for a factor of safety. I hope this helps.
Regards,
Alex
RE: Determing the point at which a weld will fail..details inside
Thanks for the link too! Im definatly going to check it out. I have found some calculator that will help me but they do not really tell how they come up with the solutions which does not do me much help.
Thanks again.
RE: Determing the point at which a weld will fail..details inside
Remember that safety people generally aren't engineers, they often request things that aren't the best technical solution. It's the engineers job to propose better solutions.
Shigley & Mischke "Mechanical Engineering Design" covers weld design to some extent, but you're going to have to make some assumptions as noted by previous replies.
RE: Determing the point at which a weld will fail..details inside
RE: Determing the point at which a weld will fail..details inside