Ive got you now, its earlier in the thread there was talk about converting it to cantilever beam, so figured that was what I needed to do.
If I just convert one side of the 1st class lever I get an answer like yours (2168.53), Divided by the section modulus gives 53.11MPa.
The original lever I calculated as a resistance of (about) 310N a distance 7mm from the fulcrum with an applied force of 85N a distance of 26mm from the fulcrum.
After this I have multiplied each lengh of the side of the lever by the force on the same side and have come up with a balanced...
Sorry haynewp, its my silly fault, for not explaining things better. I was working with a second class lever on one part of the opener, but now I am looking at another part which is a first class lever. I thought I had mentioned it before, but I havnt, so I am terribly sorry for making this very...
Sorry haynewp, its my silly fault, for not explaining things better. I was working with a second class lever on one part of the opener, but now I am looking at another part which is a first class lever. I thought I had mentioned it before, but I havnt, so I am terribly sorry for making this very...
Ive tried it keeping the units as millimetres, which gives fb = 67.4104 which appears a lot better (although I doubt it is), but I still don't know what the units are for this, am I right in assuming its Nmm?
Its been a few years since I have had to any of this, and my brain is totally fried...
Sorry to keep bothering you guys, but I've calculated the max moment. To be 2.752 (by doing - 83.405N * 0.033m).
Ive calculated the section modulus to be 0.00007m^3 (thats - 7E-5m^3).
Dividing the moment by the section modulus I get 39314.29, This seems far to big to be the bending force.
am...
THE LEVER
Effort= 85N
Length to fulcrum from effort = 26mm
Resitant force = 310N
length to fulcrum from resistance = 7mm
Converted to a beam I get:
Length = 0.02m
Force = 433.706N
Giving a moment of 8.674Nm
Dividing this by the section modulus I get
212424490Nm^2 (i think that's the correct...
Ok sussed it, almost.
Ive calculated the moment of imertia as 142.92mm^2. The cross section is 5mm wide, 7mm thick, I used the equation frm here http://darkwing.uoregon.edu/~struct/courseware/461/461_example_problems/ex_prob_lecture_28/461_example28-2.html to find the moment across the x...
Thanks haynewp, I've tried to figure out the section modulus. The equation for it is (moment of inertia)/(distance to neutral axis). The 'bar' in question of rectangular uniform cross-section. I have found hundreds of solutions for moments of inertia, but none that I can make sense of. Is there...
Thanks haynewp, I've tried to figure out the section modulus. The equation for it is (moment of inertia)/(distance to neutral axis). The 'bar' in question of rectangular uniform cross-section. I have found hundreds of solutions for moments of inertia, but none that I can make sense of. Is there...
OK, I think I've got it.
I simply convert the lever into a cantilever beam and then calculate the sheer and bendiong forces on that beam, the only load being on the end.
Have I got the right idea, or am I way off target here?
Thanks a lot guys.
Tom
Thanks Garvin, your post pretty much answered my last question (should refresh my browser more often:rolleyes:).
Like with the last question, should I combine the forces etc on both sides of the lever to create on simple cantilever beam?
Thanks for your help, Tom:bugeye:
Thanks Astronuc,
Ive got the equations for calculating the sheer stress etc in a cantilever beam or a simply supported beam, but this being a lever is confusing me.
Can I convert each side of the lever into one cantilever beam to work out the maths that way, or is this totally the wrong...
Hi everyone,
Im designing a new device for openeing bottle caps. But I am stuck, :cry:
basically I have a second class lever (pivot at one end, effort at the other and weight in the middle). The weight is 72.21N the overall length from the effort to the fulcrum is 64mm and the length from the...
Hi everyone,
Im designing a new device for openeing bottle caps. But I am stuck,:cry:
basically I have a second class lever (pivot at one end, effort at the other and weight in the middle). The weight is 72.21N the overall length from the effort to the fulcrum is 64mm and the length from the...