Objective Chapter 06: The student will learn that crankshaft design is the estimation of the shaft diameter, crankpin dimensions to ensure satisfactory strength and rigidity when the crankshaft is transmitting power under various operating conditions. | Theory and Design of Automotive Engines [AU51] Chapter No:06, Crank Shaft Objective: The student will learn that crankshaft design is the estimation of the shaft diameter, crankpin dimensions to ensure satisfactory strength and rigidity when the crankshaft is transmitting power under various operating conditions. Outcomes: The student should be able to design crankshafts for various operating and loading conditions. Prerequisites: This topic requires the student to know about, the fundamentals of Engineering Mathematics, Engg physics, Strength of Materials, Engineering Drawing, Workshop Processes, Theory of Machines, Material Science and fundamentals of Machine Design. Number of Question/s expected in examination: 01 [20Marks] INTRODUCTION: Before studying the actual crankshaft and design details, we shall study briefly the basics of Power Transmission of shafts. Power Transmitting Shaft: Shaft Design consists primarily of the determination of the correct shaft diameter to ensure satisfactory strength and rigidity when the shaft is transmitting power under various operating and loading conditions. Shafts are usually circular in cross section, and may be either hollow or solid. Design of shafts of ductile materials, based on strength, is controlled by the maximum shear theory. And the shafts of brittle material would be designed on the basis of the maximum normal stress theory. Various loads subjected on Shafting are torsion, bending and axial loads. Basics of Design for solving Shaft problems: . Maximum Principal Stress:(σ1) σ1 = σ x +σ y 2 ⎡σ x − σ y ⎤ 2 + ⎢ ⎥ + τ xy () ⎣ 2 ⎦ 2 Here and 2 refers to the formula number and page number from Design data handbook by K Mahadevan and K Balaveera Reddy, CBS Publications, INDIA, 1989. Same Data handbook and similar procedure is adopted in further discussion. Where, σx --- Stress in x direction, in MPa or N/mm2 σy --- Stress in y direction, in MPa Krishnaraja G. Kodancha, Assistant
