Example of Master Student Maintenance Engineering Exam (Essay Sample)

Maintenance engineering exam
Name of Student
Course
Name of Professor
University
Date
Design and selection of solar panel and panel
1 Definition of the problem
Solar power is an essential solution for energy crisis. Most of the solar powers installed are on the roof tops . a typical solar power consist of solar panel and a mount.
Solar panels can be mounted in different ways and before designing mounting system it is important to find determine the best way it. They are two commonly used mounting systems: they include triangle mount and single pole mount. For the triangle mount, a triangle structure is used to support solar panels while for the single pole, one pole is used for holding panel up to the center.
For this report we are designing a solar panel structure and pole for supporting solar panels. Our material selected is light, strong, stiff and cheap.
Objective
To design a cheap, strong, stiff, and light mounting post for 160 Watt solar.
Constraint
Material costs
Solar panel specifications.
N/B: The mounting post used in the design is a reinforced PVC
Mounting system.
The main concern for the design of a mounting system is its anchorage to the ground which if not well anchored, external forces will topple the system. The current anchoring system are pouring cement, adding weights and use of stakes.
For our design we will use cement. Initial a hole is dug and filled with concrete cement. after hardening it provides a strong sturdy for anchorage.
Solar panel.
The best quality solar panel for our design is polycrystalline as it is effective per unit area.
The selection of the panel depends on the wattage, size, its efficiency and frame material.
After selecting panel, calculations can be done. This include: wind loads, tipping analysis and stress analysis.
2. Derive the performance and material indices
Type of solar panel

Wattage

Dimensions

Frame
Material

From
Hole to
hole

Weight

Efficiency


160

B x D

Anodized aluminum

39 x 66

33

46.5 %

Solar panel structure:
For the
Calculations
left-73533000
\
3.Selection of the material graphical using granta.
Material

Aluminum

Density

0.099 lb/m3

Young’s Modulus

10.1 x105 psi

Flexural Modulus

10.1 x105 psi

Shear modulus

3.9 x105 psi

Yield strength

17

Compressive strength

20

Tensile strength

21

Durable

Excellent

Using the designed characteristics of the material, several material matrices were created
From the calculations, it is clear that the material cost (mounting post) is relatively cheaper than steel posts that are primarily used. In that case, the design observed costs and mechanical properties in the material selection process.
Section B
* TTT diagram for nickel based super alloy (Inconel 718)
Figure 1: TTT diagram of Inconel 718
(b)Change of structure with martensitic transformation of steel
During quenching of the austenite, martensitic transformation commences at martensitic transformation temperature, usually denoted as (Ms). As the temperature decreases, the martensite volume will increase sequentially up to the final martensitic transformation temperature (Mf). The martensitic transformation of steel will initiate structural changes that are from FCC austenite to BCC martensite. In that case, the carbon atoms in the interstitial sites within FCC do not necessarily move to the BCC randomly; instead, they move in a coordinated manner. The structural changes lead to tetragon formation with BCC lattice; hence the resulting structure results in BCT structure-Body Centered Tetragonal. The formation of the BCT increases proportionately with an increase in carbon atoms (Yeddu, 2012).
1 Above Ms (2) Below Ms (3) At Mf
(d)Various phase transformation occurring in commercial titanium alloys (Ti - 6Al - 4V)
Figure II phase diagram of Ti-6Al-4V
In phase transformation of the Ti-6Al-4V, there exists three phases: α, β(H), and d. From the diagram, hydrogen is annealed at 9000C mark. It is also notable that temperatures 8500C and 9000C are higher than the beta-transfer temperatures. The β(H) and d are stable at 8500C, while β(H) is stable at 9000C Likewise, the β(H) + d is stable above beta-transfer temperatures. The phase diagram shows that as beta-transfer temperature decreases, as hydrogen concentrations increase (Qazi et al.,2002).
* Phase transformation reactions occurring in commercial titanium alloy (Ti-6Al-4V)
(i)Peritectic reaction and Peritectic point
(ii) Peritectoid reaction and peritectoid point
QUESTION B2
Nickel based super alloys are widely used in industries that deals with service of high temperatures above 500 degrees Celsius, because they made up of carbon and elements of boron which makes them to be resistant against corrosion and of high temperature. They have high melting point and low density which are essential properties for aerospace engines with high temperatures of above 1200 degrees Celsius. During oxidation and creep, nickel super alloys are resistant to high melting point they can service high temperatures, creep is significant material that helps in avoiding seizure and engine failure in jets.
Creep is the natural condition that materials disfigure permanently due to the mechanical stress, it happens when the material are exposed to high stress for a long period of time. The three strategies used to reduce creep include;
* Using metals that have high melting point- these metals often have the better creep resistance since they can operate up to high temperature of above 600 degree Celsius reducing deformation of materials.
* Higher grain size materials- use of these materials slows creep since it reduces the grain boundaries, this is achieved through increased rate of diffusion on grain diffusion. Use of grain siz