Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MECH 321 - Properties and Failures of Materials > L13 Material Selection > Flashcards

L13 Material Selection Flashcards

1
Q

What does materials production lead to?

A

It leads to:
Materials production –> Product manufacturing –> Product use –> Product disposal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Recycle codes

Recycle code 1 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • Poly(ethylene terephthalate) (PET)
  • Used for: plastic beverage containers, mouthwash jars, peanutbutter and salad dressing bottles
  • Recycled into: Liquid-soap bottles, strapping, fiberfill for winter coats, surfboards, paint brushes, skis, cartpets, boats, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Recycle codes

Recycle code 2 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • High-density polyethylene (HDPE)
  • Used for: Milk/water/juice containers, grocery bags, toys, liquid detergent bottles.
  • Recycled into: Soft-drink bottle base caps, flower pots, drain pipes, signs, stadium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Recycle codes

Recycle code 3 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • Poly(vinyl chloride) or VINYL (V)
  • Used for: Clear food packaging, shampoo bottles
  • Recycled into: Floor mats, pipes, hoses, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Recycle codes

Recycle code 4 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • Low-density polyethylene (LDPE)
  • Used for: Plastic bags (grocery, bread, frozen food)
  • Recycled into: Garbage can liners, grocery bags, multipurpose bags
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Recycle codes

Recycle code 5 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • Polypropylene (PP)
  • Used for: ketchup bottles, yogurt containers, medicine bottles
  • Recycled into: Paint buckets, ice scrapers, fast food trays, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Recycle codes

Recycle code 6 - which plastic is it? what are its virgin material uses, and its recycled products?

A
  • Polystyrene (PS)
  • Used for: Coffee cups, utensils, grocery store meat trays, grocery store meat trays
  • Recycled into: License plate holders, desktop accessories, trash cans, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Complete the sentence:

Material selection is determined by: ___________

A

FUNCTION
(Shape sometimes influences the selection)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the taxonomic categories in the kingdom of materials and their attributes?

A

Kingdom: Material
Family: Type of material (Ceramics, Glasses, Metals, Polymers, Elastomers, CompositeS)
Class: The material (Steel, Al alloys, etc)
Sub-class: 1000, 2000, 3000s
Member: The exact material (Aluminum 5083-0)
Attributes: like Density, Modulus, Corrosion, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is material SCREENING?

A

Applying property limits – eliminate those that can’t do the job because they lack some attribute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are some common property limits during the screening process?

A
  • Minimum operating temperature
  • Electrically conducting/insulating?
  • Transparent/opaque?
  • Magnetic/non-magnetic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is material RANKING?

A

Applying material indices – which ones can do the job BETTER?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When RANKING materials, what needs to be identified?

A

Need to identify:
* Function
* Objectives (what is to be maximized or minimized)
* Constraints (what are the non-negotiables? what are negotiable but desirable?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The design of a structural element is specified by 3 things:

A

p = f[(F)x(G)x(M)]
F - Functional Requirements
G - Geometric Parameters
M - Material Properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The performance (p) can be maximized for all parameters by maximizing ____.

A

f3(M), the material efficiency coefficient, or material index

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What resources should you consult for SUPPORTING INFORMATION about materials?

A

Handbooks, softwares (like CES Selector, or Ansys Granta), internet…

17
Q

True or false:

There is one specific formula for calculating the materials index.

A

False. There is one PROCEDURE to derive the material indices for different design scenarios.

18
Q

What is the procedure for deriving material indices?

A
  1. Define the design requirements: Function (what does the component do?), Objective (what to maximize or minimize), Constraints
  2. Develop an equation for the objective in terms of the functional requirements, the geometry and the material properties (the objective function)
  3. Identify the free (unspecified) variables
  4. Develop equations for the constraints (no yield; no fracture; no buckling, etc)
  5. Substitute the free variables from the contraint equations into the objective function.
  6. Group the variables into three groups - F, functional requirements, G, geometric parameters, M material properties, where p is a function of all 3 (must be >=<)
  7. Read off the material index M, which optimizes the performance characteristic
19
Q

True or False:

Most material indices include E, the Young’s Modulus of Elasticity in their equation.

A

True. E is included for tie rods, beams, columns, springs, etc. Anything where load is involved in the function.

20
Q

Global plots of the “kingdom” of material: What are the axes, what scale do they follow, and what can we do with these plots?

A
  • These “Modulus-Density” plots have the material density as the X-axis and the Young’s modulus as the Y-axis
  • The plot has log-log scales
  • We can define min or max limits of stiffness, density, etc OR we can also plot lines of equal performance (M=E^(1/x)/ρ) of different slopes. These lines help guide material selection.
21
Q

True or False

In the Modulus-Density plot, materials in the same “circles” will have the same Performance Index P

A

False. Materials on the same LINE will have the same P

22
Q

True or False

When considering biomedical applications, like an artificial hip replacement, it is optimal to choose the best material and use it for all parts.

A

False. A variety of materials are used for each part, to satisfy different constraints.

23
Q

Slide 34 L13

Which materials are used in an artificial hip?

A

Titanium (femoral stem and shell), CoCrMo Alloy (femoral stem and head/ball), Al<sub2</sub>O3 ceramic (head/ball and liner), and Polyethylene (liner)
++ Fixation is PMMA cement

24
Q

What are the factors to consider for implant material selection?

A
  • Biocompatibility (minimum degree of rejection by body)
  • Corrosion
  • Mechanical (strength, stiffness, fatigue, etc)
  • Wear (minimize)
  • Friction (minimize)
  • Density (lower is better)
  • Reliability
  • Cost
25
Q

What materials were used for the Space Shuttle Thermal Protection System?

A
  • RCC (reinforced carbon-carbon) at the tip and wing leading edges
  • HRSI (high-temp reusable surface insulation) for lower surfaces and sides
  • LRSI (low-temp “ “) for upper surfaces and sides, tail…
  • FRSI (felt reusable “ “) for upper surfaces and sides, cargo bay doors
26
Q

When installing the thermal protection system on the space shuttle, why did the engineers leave gaps betweel the coated tiles?

A

To allow for the deformation and expansion of the metal structure under them due to thermal effects, and to permit relative motion

MECH 321 - Properties and Failures of Materials (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions