Assessment Brief 4 Student Name/ID Numbe Course BTEC HNC in General Engineering Unit...

Question

Assessment Brief 4
    Student Name/ID Numbe

    Course
    BTEC HNC in General Engineering
    Unit Number and Title
     8: Mechanical Principles
    Academic Yea
    2020/21
    Unit Tuto
    Philip Arnold
    Assignment Title
    Number 4 Natural and damped vi
ations within translational and rational mass-spring damped systems.
    Issue Date
    25th May 2021
    Submission Date
    16th June 2021
    IV Name & Date

    Allocation of time to complete assignment
    Part 1 is a written explanation which must include formulas / equations and diagrams to ratify your written explanation.
Part 2 is a calculation & written explanation type problem. You MUST show all formulas and workings throughout, underline your sub answers with red lines and highlight your final answers in pink or yellow so are easily identifiable.
At the top of every page you must type your: Name – Student ID – Qualification – Assignment number.
    Submission Format
    This is a written & problem based assessment.
To evidence that you have met the criteria:
· The written reports must be at least 200 words.
· Must show working out
· Use the co
ect units of measurement
· And use formulas right through.
Remember, answers are only part of the solution. You must show how you got there and be able to document and communicate your problem solving technique.
Some higher criteria questions will draw on you to interpret, compare and draw conclusions of worked solutions.
Format:
Part 1 is an explanation written type question.
Part 2 is a calculation. And written explanation problem.
Where references are used, follow Harvard Referencing System including in-text citations.

Student declaration
    I certify that the work submitted for this assignment is my own and research sources are fully acknowledged.
Student signature:      XXXXXXXXXXDate:
    Unit Learning Outcomes
    LO4 Analyse natural and damped vi
ations within a translational and rotational mass spring system.
    Assignment Brief and Guidance
    Scenario
You are employed in the R&D dept of an major Defence company. You are part of the team involved in designing a new Nuclear powered submarine. To avoid detection it is imperative no sound is emitted form the hull of the submarine which could be detected by an enemy submarine, surface ship or aircraft using sonar buoys.
Even though the hull is covered in sound abso
ing ru
er tiles and the propeller blade has been designed to avoid cavitation The internal machinery such as air conditioning, pumps for circulating water to the electrolysis system and pumps to pass pressurised water around the nuclear reactor and the main propulsion motors needs to mechanically isolated from the hull to aid noise elimination. Some equipment is mounted on ru
er blocks, some on steel springs due to the weight and torque involved. As motors and pumps are rotation devices, and gravity acts on the body of them two types of forces are involved. The rotating components can cause Simple Harmonic motion, and the mass of the components vertical harmonic motion also known as Harmonic resonance. You must explain how the natural frequency of vi
ation affects this
This resonance is dangerous for many reasons. Some of which are :- Metal fatigue, Can penetrate some materials which have the same harmonic resonant frequency, or third or fifth etc harmonic characteristics and escape the hull.
Part 1.
You are tasked with compiling a written technical report explaining with the aid of diagrams and equations the:- ( a ) Nature of the problem.
Part 2
A pump of mass 150 kg is suspended by 10 springs. A simulated SCRAM or in Russian” Avariynaya Zashchita 5-y kategoriisituation “ was performed on a live test bed and the pump was found to be displaced through a distance of 45mm subsequently oscillating “ Bouncing “ 90 times in 80 seconds.
You must determine:-
( a ) The periodic time
( b ) The stiffness of the spring.
( c ) The time taken for the first motion through a displacement of 25mm
( d ) The velocity at this point.
( e ) give a written explanation of what measures can be employed to reduce the oscillations in both amplitude and frequency
Resources
Textbooks
Pearson Higher Nationals in Engineering Core Text Book
John Bird & Carl Ross, Mechanical Engineering Principles, Fourth Edition, Routledge. ISBN XXXXXXXXXX
BOLTON, W XXXXXXXXXXEngineering Science. 5th Ed. London: Routledge.
TOOLEY, M. and DINGLE, L XXXXXXXXXXEngineering Science: For Foundation Degree
and Higher National. London: Routledge.
Journals
International Journal of Engineering Science.




    Learning Outcomes and Assessment Criteria
    Pass
    Merit
    Distinction
    LO4 Analyse natural and damped vi
ations within translational and rotational mass-spring systems
    P9 Explain the natural frequency of vi
ation in a Mass-spring system.
    M4 Determine the amplitude and phase angle of the transient response within a mass spring damper system.
    D4 Identify the conditions needed for mechanical resonance and measures that are taken to prevent this from happening.

hnc-assessment-4-icgxhf5q.docx

Abhijit · Accepted Answer

Part 1 
Resonance is the phenomenon which occurs in mechanical or structural elements when the 
operating frequency of the system becomes the same as its natural frequency. This is a 
serious problem that needs to be taken into consideration and needs to be minimized for the 
betterment of the mechanical or structural elements. 
In order to understand better, let’s take the example as mentioned in our problem of 
submarine. The submarine has several components inside which are mounted on foundation; 
these foundations are dashpots, rubber blocks and concrete platforms which ensure vibration 
isolation from the submarines body. Though all the vibration cannot be eliminated, every 
possible care is taken to eliminate the transmission of these machines to the submarine. The 
components that are mounted on these foundations are rotating machines such as pumps and 
reciprocating machine components such as hydraulic or pneumatic actuators for loading and 
unloading purposes of armaments inside the submarine. Both of these machines have some 
amount of unbalance is involved in them while their operation is concerned. The rotating 
elements have some eccentric mass involved in them, hence while rotating they induce some 
amount of force in the form of centrifugal force inducing vibration in the form of forced 
vibration. The reciprocating elements heavily contribute to unbalance force while their 
working, since we are aware by the fact that reciprocating masses cannot be balanced fully 
and only two-third fraction at the maximum can be balanced. 
 The submarines body too vibrates with a certain frequency; there are components such as 
propeller shaft, propellers, rudders and other electromechanical components which have a 
tendency to induce and contribute vibration. These components are constantly moving as per 
the requirement; every component according to the nature of motion induces vibration in the 
submarine; for example the propellers are heavily overcoming the viscous forces of the water 
and might contribute to the torsional vibration. The propeller shafts frequency if matches to 
the natural frequency (critical speed) might contribute some amount of vibration to the 
submarine body and there are many such factors involved. If by any means the operating 
frequency of these components matches with their natural frequency, the machine would 
shake violently and the operation of them becomes risky.

Assessment Brief 4 Student Name/ID Number Course BTEC HNC in General Engineering Unit Number and Title 8: Mechanical Principles Academic Year 2020/21 Unit Tutor Philip Arnold Assignment Title Number 4...

Solution

Answer To This Question Is Available To Download

Related Questions & Answers

Submit New Assignment