To measure the radius is quite impossible so that in the assumption the bend bar as an arc with radius R the you can write that :
the length is 2*R* sin(φ) if the two end sections make an angle of 2*φ. The deformation will be R*(1- cos(φ)). The ratio of the two gives a relative measure of bend:
B= R*(1-cos(φ))/(2*R*sin(φ)). Since angles are very small sin(φ)≈φ and cos(φ)≈1-0.5*φ^2, → B = φ/4. The angle has to be in Radian. Now it is up to you to define the which depends on the kind of loading for the bar. If it is in tension higher limits can be accepted and lower if the load is compressive. To give you an order of magnitude if you consider 2*φ =1° = 0.0174 Radian then the B = 2.2E-3 which corresponds to ≈ 2mm/m. It is important to consider this "bent" in proportion of the bar diameter since the eccentricity of the load will increase the risk of failure in case of compressive loads.
It would help if we knew what material the rods are made of.
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The rods are High carbon steel with 26 -34 Rc hardness.
Also, these rods are not load carring members. these are free rolling rods taking impact loads.
We use these rod in Ball mill for grinding operation. These rod which we have recieved are not exactly straight and got some bend in them. We measured the bend. It was approx. 7mm for rod length of 2900mm.
Do we have any standards where we can find the allowable bend or straightness for a circular rod?
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When ordering the rods you need to set the specs if none are given by the manufacturer or distributor. A lot of rod listed for general purpose has no straightness tolerance. It would help if the type of steel was known. Those steel types manufactured for specific use like shafts and axle will have tolerance specs. You should approach you supplier for the specs on straightness tolerance.
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In the case of a rod that forms a driveshaft for a marine vessel propeller, very little at all.
In the case of a rod that forms part of a reinforced cast concrete structure, the minimum bend radius is below 2 diameters.
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Allowable Bend in Rods
Re: Allowable Bend in Rods
