THEORY EXAMINATION (SEM–VIII) 2016-17 MACHINE FOUNDATION DESIGN

Section A – Basic Concept Questions (Description)

Section A consists of short conceptual questions that test the fundamental understanding of vibration theory and machine foundation design. These questions require students to explain important concepts related to dynamic behavior of foundations supporting machines.

Students must understand terms such as logarithmic decrement, damping ratio, vibration isolation, and coefficient of elastic uniform compression, which are essential for analyzing vibrations in machine foundations. The section also includes questions about types of machine foundations and hammer foundations, which are commonly used for heavy industrial equipment.

Another important aspect covered in this section is the dynamic properties of soil, which affect the performance of machine foundations. Engineers often use field testing methods to determine these properties.

The main objective of this section is to ensure that students understand the basic terminology and principles used in the design and analysis of machine foundations.

Questions for Section A

What is meant by logarithmic decrement in vibration analysis?

Define damping ratio.

What are the different types of machine foundations?

Explain hammer foundations.

What field methods are used to determine the dynamic properties of soil?

What is the coefficient of elastic uniform compression?

Why is vibration isolation important in machine foundations?

What are the common materials used for vibration isolation?

Write a short note on rotary type machines.

Name the commonly used vibration absorbers.

Section B – Descriptive Questions (Description)

Section B includes descriptive and analytical questions related to vibration analysis and machine foundation design. Students are required to derive equations, solve numerical problems, and explain testing methods used in foundation engineering.

One of the main topics in this section is free vibration analysis of single degree of freedom (SDOF) systems, where students derive the equation of motion for an undamped system.

Another important concept is the harmonic excitation response of SDOF systems, which helps engineers understand how machines generate vibrations and how these vibrations affect foundations.

The section also includes methods used to determine the natural frequency of machine foundations, such as Ford and Haddow’s method.

Numerical problems related to soil stiffness, plate load tests, and vibration block tests are also included. These tests help engineers determine parameters such as the coefficient of elastic uniform compression and damping ratio.

Students must also understand the concept of vibration isolation, which is used to reduce the transmission of vibrations from machines to surrounding structures.

Questions for Section B

Derive the general equation of motion for an undamped free vibration of a single degree of freedom system.

Determine the response of an SDOF system subjected to harmonic excitation.

Explain Ford and Haddow’s method for determining the natural frequency of machine foundations.

Calculate the percentage variation in the coefficient of elastic uniform compression when plate diameter changes.

Analyze the block vibration test data to determine the coefficient of uniform elastic compression and damping ratio.

What is vibration isolation? Explain active and passive vibration isolation methods.

What are the properties of a good vibration isolation material? Explain any two materials used for vibration isolation.

Explain the construction guidelines for providing vibration absorbers.

Section C – Long Analytical Questions (Description)

Section C contains long analytical questions that require deeper understanding of vibration analysis and machine foundation design techniques. Students must derive equations, analyze vibration systems, and explain advanced testing methods used in geotechnical engineering.

One important topic in this section is free vibration of damped SDOF systems, where students derive the expression for natural frequency considering damping effects.

Another important concept is the dynamic response of foundation blocks subjected to harmonic forces, where students calculate parameters such as natural frequency, circular frequency, and vibration amplitude.

The section also includes seismic wave propagation tests, which are used to determine soil properties such as shear modulus. Techniques like the seismic cross-hole method are used to measure wave velocities in soil.

Another important topic is the design of foundations for impact-type machines, where engineers must consider dynamic loads and vibration effects while designing foundations.

Questions for Section C

Derive the expression for the natural frequency of a damped SDOF system.

Calculate the natural frequency, natural period, circular frequency, and amplitude of vibration for a machine foundation subjected to harmonic force.

What are seismic wave propagation tests? Explain the seismic cross-hole technique used to estimate shear modulus.

Explain vibration isolation techniques used for rigid foundations.

Summarize the principles used in the design of foundations for impact-type machines.