A solid metallic rod & bar are similar to look but ASME (American society of mechanical engineers) treat them as different components, can anyone tell what's the real difference between them?
Rods, bars and beams may not always be circular cross section; it can be prismatic, uniformly varying like triangular, conical etc. Longer rods can be called as bars
I think the main difference lies in the application of external loads upon them.
Rods and bars are usually Axially loaded. So tensile and compressive stresses comes to play.
But beams are loaded Perpendicular to the axis. So bending stress as well as torsional stress are prominent...
Rod and Bar generally have circular cross-section profiles. Bars are generally more slender than Rod. They are named differently due to their usage and/or types of application viewpoints.
Beams on the other hand are found in various cross-section shapes such as (I-Beam, L-Beam, T-Beam, Channel) etc and they are used mainly in structural (engineering) constructions.
http://en.wikipedia.org/wiki/Beam
Beams can transfer bending loads (Moments) on the nodes, the other not
Rods, bars and beams may not always be circular cross section; it can be prismatic, uniformly varying like triangular, conical etc. Longer rods can be called as bars
I think the main difference lies in the application of external loads upon them.
Rods and bars are usually Axially loaded. So tensile and compressive stresses comes to play.
But beams are loaded Perpendicular to the axis. So bending stress as well as torsional stress are prominent...
beside the mentioned replies above, the differences between them are found also in type of vibration modes they can expose to. Rods are almost exposed to torsional vibration in general since they are liable to withstand torsional loads. Bars for transverse and axial vibrations due to torsional and axial loads. Beams for transverse vibration due to bending loads. Beams can also used under compression loads thus axial vibrations can be developed. Beams can be found in straight or curved configurations. curved beams are widely used in industry
I think in practice the nouns are used interchangeably with each other. I would agree that rod usually refers to a round section, whereas bar may be multifaceted. Both of these types of semi finished products may be converted via a number of manufacturing processes to other component forms via machining, forming etc. With beams (or columns) it would be much more likely to use the product as a load bearing member i.e. floor support, part of a bridge or column etc. without greatly modifying its cross section.
This may help
http://www.steelconstruction.info/Steel_construction_products
In continuation to the already stated answers above, I would like to modify/clarify few things.
The Rods/Bars are any member which are subjected to axial (Tensile/Compressive) Loads ONLY. out of which rods are definitely circular cross section whereas bars are of non-circular cross section. The Beams are the members which are subjected to Transverse loads in addition to Axial loads (if required). Transverse loads are not applied to Rods/Bars. The cross section of the beam can be circular/non-circular. BUT there are another class of members called as Shafts which are subjected to Torsional loads in addition to Axial and/or Transverse loads (if required). Torsional loads are not applied to Rods/Bars/Beams. Shafts can also be circular/non-circular. But due to generated stress in the shafts and other difficulties and moreover due to ease in manufacturing, shafts are generally of circular cross section.
i think the differece is in most important aspect of loading of a designed member; a beam is designed for strength in front of bending where a rod is designed for strength in front of axial load .
so the difference in cross sectional area is because of loading of the member. for example we want a beam to be strength in front of bending and also not to be very heavy and use less material; so we design the cross sectional area of this member in an I-shaped mode.
What is the formula to calculate strain in a rod when the load is not applied axially? (as in a side load of a pneumatic cylinder)
I think, there are several variants of all the elements you mention, therefore it is better to be more specific based on what you really need them for.
I suggest to have a look in the manual of the FE program you (are going to) use. For example, in NASTRAN, there exist elements called BEAM, BAR, ROD and variants of these keywords, like CBAR/PBAR, etc. The parameter set defining each of these variants gives the insight into how it exactly functions and how it has to be used.
When looking into the Nastran document (NXSiemens) element.pdf, it seems that a bar is a simplified version of a beam, most notably is that for a bar the intersection has to be constant anf for beams it is possible to have an taper. From this pdf:
• It must be straight and prismatic. The properties must be constant along the length of the CBAR element. This limitation is not present in the CBEAM element.
• The shear center and neutral axis must coincide (the CBAR element cannot model warping of open sections). This limitation is not present in the CBEAM element.
• Torsional stiffening of out-of-plane cross-sectional warping is neglected. This limitation is not present in the CBEAM element
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