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TORSIONAL VIBRATIONS.pptx
1. TORSIONALVIBRATIONS
CONTINUOUS ASSESSMENT #1
• NAME: PUSKAR DATTA.
• UNIVERSITY ROLL NO: 11001422022
• REG NO : 221100110159
• DEPARTMENT: TEXTILE TECHNOLOGY
• SUBJECT: THEORY OF MACHINES
• SUBJECT CODE: ES-TT301
• YEAR : 2O23
• SEMESTER: 3rd sem
• SESSION: 2023-2024
• INSTITUTE NAME: GOVT COLLEGE OF ENGINEERING AND TEXTILR TECHNOLOGY, SERAMPORE
2. CONTENT
• Introduction
• Torsional Vibration Analysis - Part 1
• Torsional Vibration Analysis - Part 2
• Torsional Vibration Measurement Techniques
• Torsional Critical Speeds
• Torsional Damping and Energy Dissipation
• Torsional Vibration in Automotive Systems
• Torsional Vibrations in Rotating Machinery
• Torsional Vibrations in Power Transmission Systems
• Advantage and Disadvantage of Torsional Vibrations
• Future Trends in Torsional Vibration Research
• Conclusion
• Reference
3. Torsional vibrations, also known as rotational vibrations, are a type of mechanical
oscillation that occurs when an object twists or rotates about its longitudinal axis.
Unlike linear vibrations, which involve back-and-forth motion along a straight path,
torsional vibrations manifest as twisting movements around a central axis.
When a torque or twisting force is applied to a mechanical system, it can induce
torsional vibrations, leading to periodic variations in the rotational angle. These
vibrations can arise in a variety of engineering applications and natural systems,
ranging from automotive drivetrains and rotating machinery to bridge cables and
DNA molecules.
INTRODUCTION
4. Torsional Vibration Analysis - Part 1
In this section, we will explore the fundamental concepts of torsional vibration analysis.
We'll begin by discussing Newton's second law for rotational motion, followed by the
equation of motion for a torsional system
Newton's Second Law for Rotational Motion
Newton's second law of motion is a fundamental principle that relates the net torque
applied to an object to its rotational acceleration. The law can be expressed as follows:
Στ = Iα
Where:
Στ represents the sum of all external torques acting on the object.
I denotes the moment of inertia of the object about its axis of rotation.
α represents the angular acceleration of the object.
5. Torsional Vibration Analysis - Part 2
In this section, we will continue our exploration of torsional vibration analysis by discussing damping in torsional
systems.
Damping in Torsional Systems
Damping is a crucial aspect of torsional vibration analysis as it affects the behavior and stability of the system.
Damping in torsional systems can be represented by the damping coefficient cθ in the equation of motion:
J d²θ/dt² + cθ dθ/dt + kθθ = T(t)
Damping serves two primary purposes in torsional systems:
1.Energy Dissipation: Damping dissipates energy from the system, converting mechanical energy into heat. This
helps prevent excessive vibrations and ensures that the system returns to its equilibrium position after
experiencing disturbances.
2.Stability: Proper damping is essential for maintaining the stability of the system. Insufficient damping can lead
to uncontrolled oscillations, while excessive damping can reduce the system's responsiveness to external
excitations.
6. Torsional Vibration Measurement Techniques
Torsional vibration measurement techniques play a vital role in understanding and assessing the behavior of
mechanical systems subjected to torsional forces. Torsional vibrations can occur in a variety of applications,
from automotive drivetrains to rotating machinery, and accurately measuring these vibrations is essential for
ensuring system performance, reliability, and safety.
Torsional vibration measurement techniques involve the use of specialized sensors and instruments to
quantify the angular displacement, velocity, and acceleration of rotating components. These measurements
provide valuable data on the system's torsional behavior, natural frequencies, damping, and response to
external excitations.
Through the application of advanced measurement technologies, engineers can identify potential issues like
resonance, excessive vibrations, and fatigue, allowing them to implement appropriate design modifications or
maintenance strategies to optimize the performance and longevity of mechanical systems operating in
torsional environments.
7. Torsional Critical Speeds
Torsional critical speeds are crucial considerations in the analysis of rotating machinery and other
mechanical systems that experience torsional vibrations. These critical speeds represent the rotational
frequencies at which a system's torsional natural frequency coincides with its excitation frequency,
leading to potentially harmful resonance effects.
When a system's rotational speed approaches or matches its torsional natural frequency, torsional
vibrations can amplify significantly, resulting in excessive angular displacements and stresses. This
phenomenon is known as torsional resonance and can lead to structural failures, increased wear and
tear, and reduced performance.
Understanding and predicting torsional critical speeds are essential for engineers in various fields, such
as automotive, aerospace, and manufacturing industries. By identifying and avoiding critical speed
regions, engineers can design systems that operate safely, efficiently, and reliably, ensuring the
avoidance of detrimental resonance effects and ensuring the longevity of rotating machinery and
mechanical systems.
8. Torsional Damping and Energy Dissipation
Torsional damping is a fundamental aspect of mechanical systems that experience torsional
vibrations. It plays a critical role in dissipating energy, stabilizing motion, and preventing excessive
oscillations in rotating machinery and other torsional applications.
Damping in torsional systems involves the dissipation of mechanical energy, converting it into
heat, and reducing the amplitude of torsional vibrations over time. This controlled energy
dissipation is essential to maintain system stability, avoid resonance, and prevent potential
structural damage.
Engineers carefully tune the damping properties of torsional systems to optimize performance
and reliability. Insufficient damping can lead to uncontrollable vibrations and resonance, while
excessive damping can diminish system responsiveness and efficiency.
By understanding torsional damping and its role in energy dissipation, engineers can design and
implement effective damping strategies to ensure the smooth operation, longevity, and safety of
mechanical systems subjected to torsional vibrations.
9. Torsional Vibration in Automotive Systems
Drivetrain Dynamics: Torsional vibrations significantly impact automotive drivetrains. The engine generates
periodic torques due to combustion cycles, which propagate through the drivetrain components, including the
crankshaft, clutch, and transmission. Managing these vibrations is crucial to ensure smooth power delivery and
optimize vehicle performance.
Clutch Engagement: During clutch engagement and disengagement, torsional vibrations can cause judder
and chatter, affecting the comfort and drivability of the vehicle. Proper damping and tuning of the drivetrain
components are essential to minimize these effects.
Dual-Mass Flywheels: Dual-mass flywheels are used to dampen torsional vibrations in the drivetrain. They
consist of two masses connected by springs and dampers, which help reduce engine-induced torsional vibrations
and gear rattle.
Torsional Dampers: Automotive engines often employ torsional dampers, also known as harmonic
balancers or vibration dampers, to reduce torsional vibrations in the crankshaft. These dampers absorb and
dissipate torsional energy, improving engine smoothness and longevity.
10. Torsional Vibrations in Rotating Machinery
1.Fatigue and Structural Integrity: Torsional vibrations can lead to cyclic loading on rotating
machinery components, such as shafts, couplings, and gears. These cyclic loads can cause fatigue
and stress concentration, potentially leading to premature failure of the equipment. Understanding
and managing torsional vibrations are vital to ensuring the structural integrity and longevity of rotating
machinery.
2.Resonance and Unbalance: Rotating machinery can experience resonance when its natural
torsional frequency aligns with an excitation frequency from external sources or unbalance within the
system. Resonance amplifies torsional vibrations, leading to excessive dynamic forces and
potentially catastrophic failure. Proper design and analysis are necessary to avoid resonance
conditions and ensure stable operation.
3.Transmission Systems: Torsional vibrations in transmission systems, such as gearboxes
and couplings, can affect the performance and efficiency of rotating machinery. Gear mesh
excitations and torque variations from the power source can induce torsional vibrations, causing
noise, vibration, and potential damage to the system. Employing torsional dampers and carefully
selecting transmission components can help mitigate these effects and improve overall system
reliability.
11. Torsional Vibrations in Power Transmission Systems
Torque Fluctuations: Torsional vibrations in power transmission systems can result in torque fluctuations. These
fluctuations can affect the performance and efficiency of the system, leading to variations in output speed and power
delivery.
Fatigue and Wear: Torsional vibrations can cause cyclic loading on transmission components such as shafts,
gears, and couplings, leading to fatigue and wear. Over time, this can result in reduced component life and potential
failures if not properly managed and mitigated.
12. Advantage and Disadvantage of Torsional Vibrations
Advantage of Torsional Vibrations:
Torsional vibrations can be harnessed for specific
applications, such as torsional energy storage devices,
where the twisting motion can be converted into useful
mechanical or electrical energy.
Disadvantage of Torsional Vibrations:
Torsional vibrations can lead to mechanical stress and
fatigue in components, potentially causing premature
failure and reducing the lifespan of mechanical
systems.
13. Future Trends in Torsional Vibration Research
Advanced Materials and Design: Future trends in torsional vibration
research may focus on exploring innovative materials with enhanced damping
and stiffness properties. Novel designs and geometries could be developed to
optimize the behavior of torsional systems, leading to more efficient and
reliable mechanical components.
Predictive Analytics and Condition Monitoring: With the advancement of
data analytics and sensor technologies, future research may emphasize the
integration of predictive analytics and condition monitoring techniques for
torsional vibrations. Real-time monitoring and analysis of torsional behavior
could lead to proactive maintenance strategies, reducing downtime and
improving the overall performance of mechanical systems.
14. Conclusion
In conclusion, torsional vibrations play a significant
role in various mechanical systems, ranging from
automotive drivetrains and rotating machinery to
marine propulsion systems. Understanding and
controlling torsional vibrations are essential for
ensuring system performance, structural integrity,
and reliability. With advancements in research,
materials, and predictive technologies, engineers
can effectively manage torsional vibrations,
optimizing the operation and lifespan of mechanical
components in diverse applications.
