Final Exam Flashcards
What is Stress?
Stress: Defined as a Force/area (sometimes called a pressure) and it’s roughly uniform across the area.
What is strength in materials?
Strength: A material’s ability to withstand an applied load without failure or plastic deformation.
What is elastic and plastic deformation?
Elastic Deformation: A temporary deformation of a material’s shape that reverts after force is off.
Plastic Deformation: Called “yield”. It’s a permanent change to shape.
What is the difference between yield strength and ultimate tensile strength?
Yield strength is the magnitude of stress where the transition from elastic deformation to plastic deformation occurs. Tensile strength is the maximum stress before the material breaks.
How do you calculate stress for a single component loaded in tension?
Stress=F/A. Use Young’s Modulus!
How do you avoid yield and breaking failures?
We need to ensure that the stress in the cable remains BELOW the ultimate tensile Strength (Sigma-UT) to prevent breaking failures and below yields strength (sigma-y) to prevent plastic deformation.
What are the benefits and challenges of CAD?
Benefits of CAD:
- Visualization of parts
- Simulation of stress, flow, etc.
- Rapid prototyping uses convenient files
Challenges of CAD:
- Locking into a design too early
- Not a creative tool
- Less collaboration
What are ethics and dilemmas?
Ethics: The study of standards of right and wrong
Dilemmas: A difficult decision where each choice has some sort of consequence.
What do you want to ensure with ethical dilemmas? What is the most important thing when making ethical decisions?
- You want to be confident you’re well inside the boundaries. This is to allow a margin of error, positively impact other people’s perception of you, and allow for risk.
- The most important tenant when making ethical decision is health, safety, and welfare of the public
What is a conflict of interests? What do you do with them?
Apotential to personally receive a benefit when carrying out your duty to a client or employer.
- They are to be avoided. First, disclose it to others (you may need to remove yourself from the decision being made).
What are the steps to the ethical process framework?
- Recognize problem
- Define the problem: gather information
- Generate alternate solutions
- Evaluate and select solution
- Optimize solution
- Iteration
What is utilitarianism?
- An ethically correct action produces the greatest benefit (or least cost) for the greatest number of people. Benefits and costs should be distributed as equally as possible, and the duration and intensity of the benefits and costs should be considered.
What is Duty-Based Ethics (Kant)?
- An ethical correct action follows universal principles (duties) that everyone should follow. These include things such as be honest, be fair, respect human life, and so on. The theory suggest we will all be happier if everyone follows these principles.
What is Rights-Based Ethics (Locke)?
- An ethically correct action is one that respects other peoples’ rights, such as the right of life, livery, and dignity. People have a duty to not infringe on other’s rights.
What is gradual escalation?
- The concept is to identify a small action with low risk and minimal negative consequences first to try to resolve the conflict. If this doesn’t work, then progressively larger steps are taken until there is a solution.
Additional Cad Tools: What is Mirror, Revolve, Pattern, Assembly?
- Mirror - creating a mirrored copy of the selected features or parts of an object.
- Revolve - creating a 3d solid or surface by sweeping a 2d sketch around an axis.
- Pattern - taking one part or feature and creating multiple copies of it in a Linear/Rectangular pattern, or in a Circular/Polar pattern.
- Assembly - combining multiple parts into a single file, and to be able to position the parts relative to one another in a desired configuration.
What are rapid prototyping technologies? What do you need to use them?
- They allow engineers to move from virtual CAD models to physical object very quickly.
- Rapid prototyping relies on computers by making direct use of the CAD files.
How does a waterjet cutter work? Benefits? Downsides?
- High pressure water combines with an abrasive material and acts as liquid sandpaper.
- It can cut through almost any material
- Often cheaper than laser cutters
- Primary limitation is that the nozzle is kept straight down at all times, which means that it’s usually used to cut flat, 2-D shapes. More sophisticated cutters can slightly adjust angle
- Also, cannot determine the cutting depth
- Lastly, cannot be used with materials sensitive to water
How do laser cutters work? Benefits? Downsides?
- A computer tells where and when the laser cuts.
- It can cut through many materials, although heavier materials require higher power lasers, which is more expense
- It’s done very quickly
- Can control the depth of cuts
- Most laser cutters are restricted to cutting flat shapes in 2-D
- Some laser cutters can make particulates, which can be harmful to people and/or the machines
How do 3D printers work? What are the two types? Benefits? Downsides?
Fuse deposition Modeling (FDM) – Plastic is melted and deposited on a shape in strips. The object is built up layer by layer.
Selective Laster Sintering (SLS) – Powder is moved into a work area. Then a laser melts and fuses the powder together to add a thin layer to the existing shape. Material is deposited layer by layer.
- SLS is usually better than FDM, though harder to get your hands on
- Primary benefit is that you can make complex 3-D objects
- They can take files straight from CAD files and make physical objects
- Although they are slow machines. Simple objects take hours!
- Materials are very limited (usually plastic, sometimes metal or wood-ish plastic)
- Design limitations: Structures can’t be too thin, or have too many unsupported internal features
What is occupational therapy and who are occupational therapists?
Occupational Therapy: A way to enable participation and independence in society.
Occupational therapists: They help people achieve the things they need, want, or are expected to do in their daily lives (MAY OR MAY NOT INCLUDE DEVELOPMENT OF ASSISTIVE TECHNOLOGY!)
What is assistive technology?
Assistive Technology: Items, equipment, or products that are used to increase, maintain, or improve functional capabilities
What do you consider when creating assistive devices?
- Consider user’s experience (age, condition, lifestyle), Usefulness, ease of use, simplicity, learning and ongoing support required, social context (appearance), and if solutions already exist
What is CLEAR in the 7 C’s
Clear – message is easy to follow, understand, and unambiguous. This means choosing appropriate language and defining jargon/acronyms
