Design based on strength is to ensure that stress at any location of the shaft does not exceed the material yield stress. Operations research is the art of giving bad answers to problems to which otherwise worse answers are given. Nt where t is the torque in nm and n is the speed of rotation in revs diagram power this is the power produced by the force of the water acting on the rotor. Draw, label and calculate the moment arms moment arms for. Torsion deformation of the twisted bar, enforce the governing equations of the theory of elasticity and from them derive simpli ed equations on a reduced set of variables. Theory questions and answers and numerical problems. In the early stage, approximate modelling establishes whether the concept will work at all, and identifies the combination of material properties which maximize performance. Typical problems and their effect on rotary lobe pumps 19 detailed look at the most common problems advising causes and solutions. Pdf problem set 8 chapter 17 shafts selected problems. Highspeed shafts require not only higher shaft stiffness but also stiff bearing supports, machine housings, etc. Video lecture on problem 1 on design of shaft from design of shafts, keys and couplings chapter of design of machine for mechanical engineering students. Shaft deformations when subjected to torsion, every cross section of a circular shaft remains plane and undistorted.
Nontrivial solutions to this set of simultaneous equations will. Determine the diameter of the shaft, neglecting the bending moment on the shaft. Surface hardening usually only used when the shaft is being used as a bearing. The design of shafts in some cases, such as those for turbopumps, is dictated by shaft. Design of shaft exam revisions important question,part1. Pdf problem set 8 chapter 17 shafts selected problems jz cls.
The gear is subjected to horizontal tangential force of 5 kn and vertical force is 2 kn in magnitude. Solutions to chapter 10 exercise problems problem 10. Machine design objectives after studying this unit, you should be able to describe types of shafts, take decisions to select the materials for shaft, estimate shaft diameters in different segments along length, and design couplings for shafts. Example 36 a circular tube with do 80 mm, di 60 mm. Non trivial solutions to this set of simultaneous equations will. An approximate analytical closed form solution is presented for the stress field produced in an isotropic homogeneous infinite plate with two unequal elliptical. Opti 222 mechanical design in optical engineering 68 torsion example problems torsion problem 1 specifications. Type of load stationary shaft rotating shaft type of. How correct system design and installation can avoid potential problems 5.
After completing this module, you should be able to. Fatigue properties dont usually benefit much from high alloy content and heat treatment. Thi qar university college of engineering mechanical engineering departmentmachine design th 4 year students manual solutions of machine design text book by khurmi and gupta solved by. Design solutions for complex engineering problems and design system components or processes that meet the specified needs with appropriate consideration for the public health and safety, and the cultural, societal, and environmental considerations. Shaft design introduction standard diameters of shafts torsion. Shaft bc is hollow with inner and outer diameters of 90 mm and 120 mm, respectively. The theory questions on shaft design contain the various question and their answers related to. In most of the practical applications shaft must be. An overall shaft design procedure is presented including consideration of bearing and component mounting and shaft dynamics using the asme design code for. Shigleys med, 10 th edition chapter solutions, page 536 9 repeating the process shown in the solution to prob. Find bending moments from gears, pulleys, or sprockets that are transmitting loads to or from other devices. The gear is subjected to horizontal tangential force. At the embodiment stage, more accurate modelling brackets values for the forces, the displacements, the velocities, the heat fluxes and the dimensions of the components. Shigleys med, 10 th edition chapter 7 solutions, page 545 74 we have a design task of identifying bending moment and torsion diagrams which are preliminary to an industrial roller shaft design.
Keys 4 a key is the piece inserted in an axial direction between a shaft and hub of the mounted machine element such as pulley or gear etc. Alfa laval solutions to specific centrifugal pump problems 4. For this reason, a common approach is to size critical locations for stress, then fill in reasonable size estimates for other locations, then perform deflection analysis. Centrifugal pumps with suggestions as to probable causes and solutions. The pulley and gear are mounted on shaft using keyways. Interference fit with hollow shaft a gear is to be press fitted over a hollow shaft of 20 mm diameter. Design of flanged coupling unprotected and protected type notations used in design. The torsion problem 1 design charts and tables 4 accuracy of the computerized solution 54 parallel shaft concept 55 bibliography 62 appendixes a mathematical model used in the clyde 63 computer program b extension of model to hollow shafts 77 distribution list 79. Pdf manual solutions for machine design by khurmi and. An overhanging steel shaft with an attached 60 lbm grinding wheel is shown in p17.
Lund uc davis fall 2017 3 some thoughts on optimization all models are wrong, but some are useful. Can design key to be weakest link to fail in case of overload. The shaft may be assumed to be made of mild steel with an allowable shear stress of 42 mpa. Useful solutions for standard problems preface modelling is a key part of design.
Surface hardening usually only used when the shaft is being used as a bearing surface. Determine the length of the contact line and the contact ratio. Soderberg failure theory three distinct proposed failure theories for fatigue design application will now be presented and discussed. The strain is that much that the hollow shaft will deform plastically. Exercise problem 1 it is somewhat difficult to conceptualize the true difference between 103 and 106 events, which have great significance in fatigue, without.
The minimum critical frequency for the shaft must be equal to or greater than 75hz. Highspeed shafts must be carefully checked for static and dynamic unbalance and for firstand secondorder critical speeds. Problem 1 on design of shaft design of machine youtube. Determine the smallest safe diameter of the shaft if the shear stress. Compute forces acting on shafts from gears, pulleys, and sprockets. Determine torque in shafts from gears, pulleys, sprockets, clutches, and couplings. Select its configuration, in other words, choose the elements that will be mounted on the shaft for the desired power transmission and choose the attachment system for each of these elements to the shaft.
Define the required angular speed and transmission power specifications. Shaft design based on strengthshaft design based on strength. Combined shock and fatigue factorscombined shock and fatigue factors. However, design method remains the same for axle and spindle as that for a shaft. You may assume that there are no axial loads and that the material selected will be steel with the following properties. Shaft coupling design article containg design procedure and numerical problems of different types of couplings commonly used.
Type of load stationary shaft rotating shaft type of load kmktkmkt. Design a shaft to support the attachments shown below with a minimum design factor of safety of 2. Due to the uniqueness of solutions, we can be sure that the assumptions made and the solutions found are correct for the torsion problem. Shaft materials shafts are commonly made from low carbon, cd or hr steel, such as aisi 10201050 steels.
Deflection of the shaft, both linear and angular, should be checked at gears and bearings. The shaft design for combined loading is most critical problem in practical. Crosssections of noncircular nonaxisymmetric shafts are distorted when subjected to torsion. In dod students present existing advanced machines chosen using different sources or their own industrial. Video lecture on problem 1 on design of shaft from design of shafts, keys and couplings chapter of design of machine for mechanical. From the solution to the preceding problem we found that n c 2949 rpm for a 2 in. T 4 knm g 27 gpa determine a maximum tensile, compressive and shear stresses b maximum strains. It includes information on general centrifugal pump problems and their effect on centrifugal pumps with suggestions as to probable causes and solutions.
Shaft power this is the mechanical, power output of the turbine shaft. Shafts are designed on the basis of strength or rigidity or both. For the loading shown, determine a the minimum and maximum shearing stress in shaft bc, b the required diameter d of shafts ab and cd if the allowable shearing stress in these shafts is 65 mpa. Define and give examples of define and give examples of the terms torque, moment arm, axis, and and line of action of a force. Useful solutions for standard problems dartmouth college. At the embodiment stage, more accurate modelling brackets values for the forces, the displacements, the velocities, the heat fluxes. In the early stage, approximate modelling establishes whether the concept will work at all, and identifies the combination of material properties that maximize performance. Design based on rigidity is to ensure that maximum deflection because of bending and maximum twist due to torsion of the shaft is within the allowable limits.
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