ABE 61 Machine Design for AB Production PDF

 ABE 61 MACHINE DESIGN FOR AB PRODUCTION  Central Mindanao University College of Engineering Department of Agricultural and Biosystems Engineering SHAFT DESIGN AND ANALYSIS ABE61 –Machine Design for Agricultural and Biosystems Productio...

 ABE 61 MACHINE DESIGN FOR AB PRODUCTION  Central Mindanao University College of Engineering Department of Agricultural and Biosystems Engineering SHAFT DESIGN AND ANALYSIS ABE61 –Machine Design for Agricultural and Biosystems Production Ablen, N.M., Alipio, F.G., Asotigue, F.A., Atienza, C.M., Baldoque, C.J., Baquilid, HJ.,  Shaft Design and Analysis Introduction Shaft is a rotating machine element which transmits power from one point to another point. It is one of the most common and basic machine elements which are used in a variety of ways in mechanical equipment. It is used with power transmission elements like gears, pulleys, flywheels, cranks, etc. These shafts are designed to transmit the required torque and to support the rotating elements like gears and pulleys. These elements produce bending moment in addition to torque. A shaft must be strong enough to sustain static and dynamic loading.  Shaft Design and Analysis Types of Shafts Shafts are classified as follows according to their industrial applications: Line Shaft Spindle Stub shaft Counter shaft It is a shaft which A spindle is a short A shaft that is integral A short shaft that transmits power to several revolving shaft. with an engine, motor or connects a prime mover machine elements. Example: Headstock prime mover is known as to a line shaft of a spindle, Drill press stub shaft. machine is known as spindles, etc. counter shaft  Shaft Design and Analysis Types of Shafts According to the applications, shafts may be divided into two types. Transmission shafts These shafts transmit power between the source and the machines and absorbing power. Counter shafts and line shafts are transmission shafts.  Shaft Design and Analysis Types of Shafts According to the applications, shafts may be divided into two types. Machine shafts These shafts form an integral part of the machine itself. Example: Crank shaft, stub shaft.  Shaft Design Failure Strength The maximum stress a material can withstand before failure occurs. This includes various types of strength, such as static and fatigue strength. Static Strength The ability of a material to withstand a constant load without deforming or breaking. It is measured under static conditions, where loads are applied gradually and held constant. Fatigue Strength The maximum stress a material can endure for a specified number of cycles without failing. It is crucial for materials subjected to repeated loading and unloading.  Shaft Design Shaft Deflection The displacement of a shaft from its original position due to applied loads. It can occur in various forms depending on the nature of the load. Bending Deflection The deflection that occurs when a shaft is subjected to bending moments, causing it to curve. This is typically calculated using beam bending equations. Torsional Deflection The angular displacement of a shaft when subjected to torque. It measures how much the shaft twists under load. Slope at Bearings and Shaft-Supported Elements The angle of inclination at points where the shaft is supported, which affects the load distribution along the shaft.  Shaft Design Shear Deflection Due to Transverse Loading of Short Shafts The deflection experienced by short shafts when subjected to transverse loads, which can lead to shear stress concentrations. Critical Speeds at Natural Frequencies The specific rotational speeds at which a rotating shaft experiences resonance, leading to excessive vibrations. These speeds correspond to the natural frequencies of the system and must be avoided in design to prevent failure.  Shaft Design Torque Transmission Torque transmission refers to the process of transferring rotational force from one component to another, typically from a motor or engine to a shaft. This is crucial in machinery and vehicles for effective power transfer. Common means of transferring torque to shaft ▪ Keys – most effective ▪ Splines ▪ Setscrews ▪ Pins ▪ Press or shrink fits ▪ Tapered fits  Shaft Material Deflection Primarily influenced by the geometry of the shaft rather than the material itself. Strain Controlled by geometry, but material properties impact stress levels. – Strength Yield strength or Ultimate Tensile Strength (UTS) are key material properties. Cold Drawn Steel Recommended for diameters less than 3 inches. Hot Rolled Steel Commonly used for larger shaft sizes; should be machined throughout. Production Methods: Low Production Quantities Prefer machining for precision and detail. High Production Quantities Forming is more efficient for mass production.  Shaft Material Steel Carbon Steel Commonly used for general applications due to good strength and toughness. Alloy Steel Offers enhanced properties for high-stress applications Stainless Steel Corrosion-resistant, ideal for food, pharmaceutical, and marine applications. Aluminum Lightweight and resistant to corrosion, suitable for low-load applications. Composite Materials Used for specialized applications where weight reduction is critical. Bronze Offers good wear resistance and is often used in bearings  Shaft Material Table 1. list of some materials common used for shafts and their mechanical properties Material Ultimate Tensile Strength Yield strength N/mm2 N/mm2 Plain Carbon Steels C 07 320 – 400 200 C 10 340 – 420 210 C 15 370 – 490 240 C 20 440 – 520 260 C 25 460 – 550 280 C 30 500 – 600 300 C 40 580 – 680 330 C 45 600 – 750 380 C 50 660 – 780 380 40 Ni 3 750 – 1050 600 40 Ni4 Cr1 1000 – 1150 600 40 Cr 3 Mol v20 1350 1120 40 Cr1 700 – 850 540  Shaft Material Commercial shafts are available in the following preferred sizes (in mm) as per IS 3688-1977: 5, 6, 7, 8, 10, 11, 12, 14, 16, 18, 20, 22, 25, 28, 32, 36, 40, 45, 50, 60, 63, 65, 70, 71, 75, 80, 85, 90, 95, 100, 122, 140, 160, 180, 200, 260, 280 and 300.  Shaft Layout Consideration Alignment Ensure shafts are properly aligned to reduce wear and increase efficiency. Support Bearings Position bearings to minimize deflection and support shaft loads. Length and Diameter Select dimensions based on load requirements and space constraints. Couplings Incorporate couplings for connecting shafts and accommodating misalignments. Clearances Maintain adequate clearances for thermal expansion and movement. Access for Maintenance Design layout to allow easy access for inspection and maintenance. Safety Features Include guards and safety mechanisms to protect personnel from moving parts.  Shaft Layout Straight Shaft Layout Offset Shaft Layout Simple design; used for direct power Allows for changes in direction of power transmission. Minimal supports needed. transmission. Requires additional supports and couplings. Geared Countershaft Single Cardan Shaft  Shaft Layout Cantilever Shaft Layout Multi-Shaft Layout One end is fixed while the other extends freely. Multiple shafts working together, often Useful for applications with limited space. connected by gears or couplings. Allows for complex machinery arrangements. Fan Shaft Twin-Shaft Gas Turbines  Shaft Layout Vertical Shaft Layout Interconnected Shaft Layout Used in applications like wind turbines or Shafts connected at various angles, often seen in elevators. Requires specialized bearings to complex machinery. Requires precise alignment support vertical loads. and careful consideration of load distribution Worm Gear Speed Reducer Twin-Shaft Gas Turbines  Shaft Layout Longitudinal Shaft Layout The shaft runs parallel to the primary direction of motion or force. Common in machinery where power needs to be transmitted in a straight line, such as in conveyor systems or linear actuators. Simple design, easier alignment, and minimal deflection. Horizontal Shaft Layout Shaft oriented horizontally, often used for straightforward power transmission. Typical in motors and generators. Axial Shaft Layout The shaft extends along the axis of rotation, typically in applications where the shaft experiences rotational motion. Found in rotating equipment like motors, pumps, and turbines. It is efficient power transmission with reduced friction and wear.