Seminar Details

Seminar Title
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MODELLING AND ANALYSIS OF VARIOUS ISSUES IN VISCOELASTIC COMPOSITE ROTORS
Seminar Type
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Synopsis Seminar
Department
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Mechanical Engineering
Speaker Type
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Student
Speaker Name
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KRISHANU GANGULY ( RollNo : 516ME1002)
Date  &  Time
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01 Mar 2021  04:30 pm
Venue
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MS Team code: e7wpkqi
Contact
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Prof. Haraprasad Roy
Abstract
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Apart from balancing, replacing heavy metals with viscoelastic substances exhibiting lesser density and proficient material damping mechanism can stand as an alternative to reduce the excessive vibration. However, the main disadvantage of viscoelastic material is its low elastic modulus, which can be overcome by reinforcements. Composite materials have been extensively used for rotor design due to their lightweight, environment-friendly, low cost, quality, and better performance. Hence, along with proper modelling of rotor systems with asymmetries due to internal damping, it also becomes important to model the shaft considering the laminated nature of the composite that would satisfy both symmetric and non-symmetric stacking sequences. The study proposes a novel mathematical technique named Equivalent Modulus Theory (EMT) to model viscoelastic laminated composite shafts and compare it to another method known as Direct Procedure Technique (DPT). The operator-based constitutive relationship is endorsed to each lamina to integrate the material damping leading to a higher-order finite element model. Timoshenko beam theory is used in the finite element formulation to incorporate the shear deformation effect. Numerical results are acquired through eigen analysis and unbalance response. The study is further continued to carry out the dynamic analysis of the composite rotor systems subjected to an important issue, i.e., cracks. A novel mathematical formulation for breathing mechanism is proposed based on random optimization technique. This stiffness matrix is incorporated into the previously obtained higher-order FE model to study the effect of crack on stacking sequence and mode shapes of the heterogeneous laminated shaft. The issue of bulky and complex finite element model of realistic propeller shaft system leading to higher computational time is dealt with the application of reduction process, i.e., Modified SEREP (System Equivalent Reduction Expansion Process).