Problem on calculation of diameter of solid shaft torsion. Similar to structures under tension or compression, two important mechanical properties of shafts under torque loads are shear stress and shear strain. Comparative study of hollow and solid shaft for the. The geometric dimensions of the notched shaft are shown in figure 4. The diameter of the hollow shaft is more than the solid shaft and require more space. For a hollow shaft, the polar moment of inertia j, is given by j o.
Torsion of solid and hollow shafts stress mechanics. For a constant outside diameter the solid rod is much stronger. Comparison between solid and hollow shafts, in this tutorial you will learn about comparison between solid and hollow shafts. Hollow shafts may be analyzed by using the computer program directly or by using the solid shape charts in this report and the orinciples of superposition based on the concept of parallel shafts. The natural frequency of hollow shaft is higher than the solid shaft with the same weight. I dont want to miss out on all the good stuff why a hollow shaft tends to resist torsion better than a solid one. The sizes of the woodruff keys chosen are shown in tables 2 and 4. Stresses in thickwalled cylinders thickwalled cylinders have an average radius less than 20 times the wall thickness. The propeller shaft of an aircraft engine is steel tubing of 75 mm external and 60 mm internal diameter. From the experiment, the shear elastic modulus g, shear proportional stress. The strength of a shaft implies the maximum torque it can transmit. This relationship can also be used for a hollow shaft.
The torsion of solid or hollow shafts polar moment of inertia of area. Torque transmitted by a hollow shaft subjected to torsion. Hollow shafts are having a more polar moment of inertia, thus they can transmit more torque compared to solid shafts. If you wanted further proof of that, you could look and see that the torsion constant of a solid shaft is pi2 times the the radius of the shaft raised to the fourth power, while the torsion constant of a hollow shaft is pi2 times the difference of the outer radius to the fourth minus the inner radius raised to. Torsion of solid and hollow shafts polar moment of inertia of an area. The shaft has a machined surface finish and an ultimate tensile strength of 552 mpa. Simply use the outside radius, r o, to find the polar moment of inertia for a solid shaft, and then subtract the polar moment of. Hollow shafts are much better to take torsional loads compared to solid shafts. Home courses aerospace mechanics of materials course materials exercises hollow vs. Torsion, like a linear force, will produce both stress and the strain.
They provide more positive shaft alignment which is especially important when the pumps have mechanical seals rather than packing. Experimental test results for solid and hollow beams with the same outside dimensions and identical areas of torsion reinforcement, shown in figure 5. Shaft design includes the determination of shaft diameter having the strength and rigidity to transmit motor or engine power under various operating conditions. Crosssections for hollow and solid circular shafts remain plain and undistorted because a circular shaft is axisymmetric. Torque is a force required to rotate the hollow shaft at a fixed axis.
Me 457 experimental solid mechanics lab torsion test. Both solid and hollow members are considered as tubes. A hollow shaft has greater strength and stiffness than a. The shaft torsion utility program shaft used for the generation of the data in this hand. Crosssections of noncircular nonaxisymmetric shafts are distorted when subjected to torsion. Since it was mentioned in the question i linked the two. Arradcom lmary defense technical information center. Hollow shaft utilize material strength more efficiently, so hollow shaft used if you concerned about weight. Solid shaft drivers are used to drive pumps with relatively short shafts, less than 30 to 50 ft long. When a shaft or a bar is loaded from above using heavy weights, the bar or the sha. If youre talking about the bending strength of a hollow vs.
A solid rod will be stiffer both in torsion and in bending than a hollow rod of the same diameter. Otherwise, it can be referred as a force needed to twist the hollow shaft. If you see the shear stress diagram of a shaft on application of torque it would look like. A solid shaft will always be stiffer than a hollow shaft with all other material properties being identical. Power transmission in solid and hollow shaft exergic. Torque transmitted by shaftsolid total turning moment due to turning force total.
A hollow shaft has greater strength and stiffness than a solid shaft of equal weight. Power transmission shafts on motors and gearboxes, for example are subjected to torque loads that result in torsion, or twisting of the shaft about its axis. For a shaft carrying primarily torsion loads, it is the. When a shaft is subjected to a torque or twisting a shearing stress is produced in the shaft. Shaft 2 has a centered hole in it and is 50% the weight of shaft 1. For a circular shaft, plane sections remain plane for a rectangular shaft, these cross sectional planes warp imagine a shaft composed of a series of rigid disks, each disk slips relative to its neighbor to produce deformation. Difference between hollow shaft and solid shaft mechopedia. Comparison of hollow and solid shaft by strength youtube. In either case, it is subjected to torsion and the stresses set up by every crosssection are shear stresses. A hollow shaft made of nodular cast iron is used to transmit torque within an automatic transmission. Shear stress in the shaft when a shaft is subjected to a torque or twisting, a shearing stress is produced in the shaft. However, for a given weight or amount of material the hollow rod is much stronger.
The engineer has the following two design constraints and two design options. So, it can be said that the bending stress developed in a hollow shaft is lesser than that at a solid shaft of same weight or in other word, hollow shaft is. Comparison between solid and hollow shafts som tutorial 5. Torsion of solid shafts strength of materials stress. A shaft is made of solid round bar 30 mm diameter and 0.
Lecture torsion in solid and hollow shafts 1 slideshare. It depends on torsional rigidity of the shaft since it renders the stiffness to the shaft. When subjected to torsion, every crosssection of a circular shaft remains plane and undistorted. But, when weight is not a concern, solid shaft is better stronger, of course, easy to fabricate. Hollow shafts do not transfer more power but the power to weight ratio of hollow shafts is. Torsion of shafts the torsion of solid or hollow shafts polar moment of inertia of area. Compare the torsional stiffness of a solid shaft 50 mm diameter, 300 mm long, with that of a hollow shaft of the same material having diameters 75 mm, 50 mm and length 200 mm. Hollow shaft is a rotating shaft, which uses lighter metal but hold strength similar to solid shaft of the same diameter. Torsion of shafts torsion occurs when any shaft is subjected to a torque. Homework statement assuming that the maximum shear stress and torsion are the same in both shafts design a hollow shaft to replace the solid one.
Torsion of circular shafts ea0221 semester 3 20152016 department of mechanical engineering national university of singapore objectives the main objective of the experiment is to study how a hollow shaft would behave compared with the solid shaft, in terms of strength and rigidity under torsion. Solid and hollow shafts introduction the purpose of torsion testing usually parallels that of uniaxial tension tests. The formula for the polar second moment of area is 32 dd. One way to check for strength or stiffness is to load the shafts by weights and see which one would be more likely to bear greater compressive and tensile stresses. When the shaft is subjected to combined twisting moment ad bending moment then the shaft must be designed on the basic of two moments simultaneously. If you are asking about the shaft which can resist the torsion load more with the same resisting area same weight, than the answer should be hollow shaft. Before selection of shaft you must considered whether to choose hollow shaft or solid shaft depending upon type of application, power requirement, torque transmission requirement, weight, cost, machining time, material. Since both are the same materials and all im trying to do is duplicate the amount of torque and stresses that the solid shaft is able to handle what formulas andor thumbrules would you consider best for using, thanks. In many cases the shaft is to be designed from rigidity point of view. Parallel shaft concept 55 bibliography 62 appendixes a mathematical model used in the clyde 63. Torsional rigidity is defined as the torque required to produce a twist of one radian per unit length of. Shafts are usually round and may be solid or hollow.
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