Design and CAD Final 1st Half Cards

Process

A rational progression of actions

Developing

Involves evaluating, iterating, and refining

Satisfactory

Not perfect or ideal; a compromise

Idea

Requires thinking, creativity, and imagination

Specific

Success depends on meeting defined requirements

What is the most important step of the engineeing process?

Problem definition

What is the order of the design process?

Problem definition → Ideation → Concept development → Prototyping → Testing → Evaluation

What are the subsections of the design process?

Ethics, Feasibility, Impact

What are the sub-subsections of the design process?

Technical, People, Commercial, Organizational

What should be in a design specification?

What is required, what is desired, and what are the constrains.

What are stakeholders

A stakeholder is a party with a vested interest in an enterprise.

A planetary gear with a fixed gear has what input and output?

Input: Sun Gear - Output: Ring Gear

A planetary gear with a fixed gear has what input and output?

Input: Sun gear - Output: Carrier

The problem definition stage of the design process often includes?

1. Identifying a potential problem to solve

2. Validating the problem to ensure it is worth solving

3. Defining the specifics of the problem

The design problem and solution parameters are defined in a design…

Specification

What are the gear ratio equations?

What is the torque equation?

T = L X W

Relationship of the torque of a motor to a weight hung on it.

Force to torque and pitch radius relation/equation

Pitch equation

Module is 2x the pitch, true or false?

False, it is the inverse of pitch (1/P)

Planetary gear equations

What was the first known technical drawing?

Statue of Gudea

Who was the advocate of orthographic drawings?

Marcus Vitruvius Pollio “De Architectura”

Who invented Cartesian coordinates?

Renee Descartes

What was the main reason dimensioned drawings were standardized?

Interchangable parts, also led to quality measuring tools

What was the first true CAD software

"Sketchpad”

What is the US Standard also called

3rd Angle Projection (British is 1st angle projection)

The generic design solution features

Energy, Material, and Information into and out of the system

What is the goal of the ideation process?

To generate lots of different ideas

What is ideal for brainstorm

• 5-15 people with a leader

• Diverse backgrounds

• Equals

• Focus on one function only

• Write down or sketch all ideas

• Quantity is the goal

• Not judging/criticism

• 30-45 mins max per session

What is design fixation?

Focusing too much on your first ideaA v

A view on a plane parallel to an inclined surface that shows its true size and shape is called a ____ view.

Auxiliary view

Are hidden lines generally included on auxiliary views?

No, unless needed for clarity

For an auxiliary view, can a centerline continue between adjacent views?

Yes, to indicate alignment

How do you see interior details of an object that cannot be seen from the outside?

A section view

What view is this?

A section view

What are these

Cross-hatching styles

Stiffness, Strength, Hardness, Toughness, Endurance limit, Wear-resistance, Coefficient of friction are all examples of…

Mechanical material properties

Conductivity, Diffusivity, Heat Capacity, Coefficient of Expansion are all examples of…

Thermal material properties

Resistivity and Permittivity are examples of…

Electrical material properties

Remanence and Saturation Magnetization are examples of…

Magnetic material properties

Refractive index and Absorptivity are examples of…

Optical material properties

Corrosion resistance, Toxicity, Degradability are examples of…

Chemical properties

What is this

Uniaxial tension

When does a uniaxial tension graph become linear?

What are the stress and strain equations

What is shear, and what are its stress and strain equations

Stiffness

Resistance to elastic deformation. Relates stress & strain.

Structural stiffness

Resistance to elastic deformation. Relates load and displacement.

Spring stiffness

Structural stiffness of a spring

Strength

Resistance to the onset of plastic deformation

Material strength graph, locate points of interest and what they are.

You can strengthen or “work-harden” a material by putting stress on it past the yield strength, true or false?

True

What is hardness (and an example of something that demonstrates it)

Resistance to local plastic deformation, typically on the surface (example would be a gear or shaft)

How do you test hardness?

With an indenter

Is hardness a direct measure of strength?

No, but strength can be estimated from hardness

Toughness

Resistance to fracture

Fracture

Propagation of a crack in the material

If the fracture toughness exceeds the stress intensity factor, a crack propagates. True or false?

False, its the other way around

Brittle

Once a crack starts to grow,
It continues to grow with very little plastic
deformation (yielding)

Ductile

Material around crack tip yields and inhibits additional crack growth

Fatigue

Progressive and localized damage due to
cyclic loading

Endurance limit

When does friction and wear happen?

When real contact area is less than surface area

Abrasive wear

Material at the tips of a harder material breaks off the tips of a softer material, creating wear particles.

Adhesive wear

Material at the tips of one surface bonds to the other surface and is torn off.

- Crystalline with metallic bonds
• Stiff – high 𝐸
• Tough – high 𝐾𝐼𝐶
• Ductile
• Wide range of strengths depending on
composition and processing
• Thermally and electrically conductive
• Reactive – low corrosion resistance
• Mostly used as alloys

Are the characteristics of what

Metals

• Crystalline with ionic and/or covalent bonds
• Stiff – high 𝐸
• Hard
• Abrasion resistant
• Brittle – low 𝐾𝐼𝐶
• Good high temperature strength
• Good corrosion resistance
• Should avoid loading in tension

Are the characteristics of what

Ceramics

-Non-crystalline with ionic and/or covalent bonds
• Hard
• Brittle – low 𝐾𝐼𝐶
• Corrosion resistant
• Electrically insulating
• Transparent (mostly)

Are the characteristics of what

Glasses

-Long chain molecules with covalent and secondary bonds
• Properties are highly sensitive to temperature
• High strength per unit weight (𝜎𝑦/𝜌)
• Light weight – low 𝜌
• Easily shaped
• Low stiffness – low 𝐸

Are the characteristics of what

Polymers

• Long chain cross-linked molecules
• Able to retain initial shape after being stretched significantly
• Non-linear elastic stress-strain behavior
• Relatively strong and tough

Are the characteristics of

Elastomers

• Properties dependent on a combination of materials
• Difficult to shape and join
• Expensive

Are the characteristics of

Hybrids

What are dimensions used to indicate

Size and location

Welding

Components joined by locally
melting the work pieces together
with a filler metal
“TIG” – Tungsten Inert Gas welding
“MIG” – Metal Inert Gas welding

Lugs and brazing

Components joined by melting a filler metal which then flows into the gaps between the work pieces through capillary action