11: Material Selection Strategies Quiz
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Questions and Answers

Which of the following is NOT a step in the material selection strategies?

  • Implementation (correct)
  • Screening
  • Translation
  • Ranking

It is essential to disregard previous choices when making new decisions in the design process.

False (B)

What is the main criterion used for ranking candidates in material selection?

Maximizing or minimizing a specific criterion based on performance and behavior.

The iterative process should always pay attention to one’s own _____ during material selection.

<p>biases</p> Signup and view all the answers

Match the following steps in the material selection process with their descriptions:

<p>Translation = Reinterpret design requirements to identify viable materials Screening = Derive attribute limits from constraints Ranking = Order candidates based on specific criteria Validation = Seek documentation for top-ranked candidates</p> Signup and view all the answers

What is the primary material used in the design of the peeler's handle?

<p>Santoprene (B)</p> Signup and view all the answers

The oval shape of the handle is considered aesthetically pleasing and popular at the time.

<p>True (A)</p> Signup and view all the answers

What ergonomic purpose do the fins serve in the design?

<p>Provide a comfortable grip for thumb and index fingers.</p> Signup and view all the answers

The manufacturing process involves molding the material known as __________.

<p>Santoprene</p> Signup and view all the answers

What is a key aesthetic feature of the handle's design?

<p>Thin parallel ribs (D)</p> Signup and view all the answers

Match the design features with their corresponding purposes:

<p>Countersunk Hole = Reduces manufacturing cost Ergonomic Grip = Enhances comfort for user Oval Shape = Aesthetic appeal Thin Parallel Ribs = Lightweight appearance</p> Signup and view all the answers

What is essential when ranking candidates after screening?

<p>Quantifiable data on performance (B)</p> Signup and view all the answers

The countersunk hole in the design is intended to have a more pronounced appearance.

<p>False (B)</p> Signup and view all the answers

The top-ranking candidate is always suitable for the target use case.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the holding tolerance of the fin shape in the peeler's design?

<p>To maintain the structural integrity of Santoprene.</p> Signup and view all the answers

What is used to quantify the overall importance of multiple objectives in candidate ranking?

<p>Weights</p> Signup and view all the answers

A performance index allows for ranking based on the measure of __________.

<p>performance</p> Signup and view all the answers

Match the following performance properties with their descriptions:

<p>Density (ρ) = Mass per unit volume Strength (σf) = Resistance to deformation Performance Index = Ranking measure Feasibility Check = Assessment of suitability for use</p> Signup and view all the answers

What should be checked to ensure the suitability of selected materials?

<p>Feasibility and unknowns (A)</p> Signup and view all the answers

Performance indices only consider single properties for material ranking.

<p>False (B)</p> Signup and view all the answers

What do performance indices allow in terms of property ranking?

<p>Ranking of the property of interest</p> Signup and view all the answers

Which material is known for having a good reputation and being biodegradable?

<p>Cork (A)</p> Signup and view all the answers

Soft Polymer Foam is a renewable resource.

<p>False (B)</p> Signup and view all the answers

What is an important tool used for material selection?

<p>Ashby charts</p> Signup and view all the answers

Cork is primarily produced in _____ and Portugal.

<p>Spain</p> Signup and view all the answers

Match the material with its characteristic:

<p>Cork = Biodegradable and renewable Soft Polymer Foam = Oil-based and fast production Plywood = Locally produced and mitigated wood imperfections</p> Signup and view all the answers

What aspect does material selection NOT primarily consider?

<p>Color Variety (C)</p> Signup and view all the answers

Production time of plywood is slower compared to soft polymer foam.

<p>True (A)</p> Signup and view all the answers

What should be considered as part of the requirements in material selection?

<p>Sustainability indices</p> Signup and view all the answers

Which material is suggested as an optimal choice due to its performance characteristics?

<p>CFRP composite (C)</p> Signup and view all the answers

The side length of the beam is considered a free variable in the material selection process.

<p>True (A)</p> Signup and view all the answers

What happens to the beam's geometry when different materials are selected?

<p>The beam's geometry changes, which affects the side length 'a'.</p> Signup and view all the answers

To maintain a fixed mass with lower densities, a ______ beam is required.

<p>wider</p> Signup and view all the answers

Match the material with its property regarding beam selection.

<p>Wood = Higher density means narrower beam CFRP composite = Lower density requires wider beam Steel = Moderate density affects side length Aluminum = Lightweight and strong structure</p> Signup and view all the answers

What does the variable 'α' equal when using the formula for mass calculation?

<p>2 (A)</p> Signup and view all the answers

Only two parameters are considered for material selection according to the guidelines.

<p>False (B)</p> Signup and view all the answers

What formula represents the relationship between mass, density, length, and area?

<p>m = ρLA²</p> Signup and view all the answers

What is the purpose of selecting the material of a beam in this design problem?

<p>To minimize the mass while maintaining stiffness (C)</p> Signup and view all the answers

The mass of the beam increases with higher values of density (ρ).

<p>True (A)</p> Signup and view all the answers

What equation represents the deflection of a beam in three-point bending?

<p>$\delta = \frac{FL^3}{48EI}$</p> Signup and view all the answers

The second moment of area for a beam with square cross-section is given by _____.

<p>$I = \frac{1}{12}a^4$</p> Signup and view all the answers

Match the symbols with their corresponding meanings in beam bending equations:

<p>F = Applied force L = Length of the beam E = Modulus of elasticity I = Second moment of area</p> Signup and view all the answers

What is the relationship between performance and mass in this design problem?

<p>Performance is inversely proportional to mass (D)</p> Signup and view all the answers

What variable is being eliminated in the mass formula for the beam design?

<p>$a$</p> Signup and view all the answers

The stiffness of a beam does not affect its deflection under load.

<p>False (B)</p> Signup and view all the answers

Flashcards

Material selection process

A multi-step process that involves translating design requirements, screening materials, ranking viable candidates, and validating choices.

Iterative and convergent process

The material selection process repeatedly refines choices until a suitable material is identified.

Bias awareness

Recognizing and managing personal biases to ensure objective material selection.

Design requirements translation

Converting design specifications into material attributes for easier comparison and selection.

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Validation step

Scrutinizing the top material choices concerning their documentation, past use, and behavior in particular situations.

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Oxo Goodgrips Peeler

A kitchen tool with an oval handle, fins, and a countersunk hole.

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Ergonomics (peeler)

The optimum shape of the handle for a comfortable grip.

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Aesthetics (peeler)

The overall shape of the peeler, often mimicking other popular styles.

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Santoprene

A polymer that acts like rubber but is molded like plastic.

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Manufacturing challenges (peeler)

The shape and material (Santoprene) can be hard to perfectly mold.

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Countersunk Hole(peeler)

A recessed hole in the handle for easier positioning and cost reduction.

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Holding Tolerance (Fins)

The ability to maintain the shape and dimension of the product's fins.

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Cross-section (handle)

A specific cut that shows the peeler's handle from the side.

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What's the goal of ranking?

To order candidates (materials) based on a metric that measures performance, helping to identify the most suitable options.

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Performance Index

A quantifiable measure (like a number) that tells us how well a candidate material will perform based on a specific criteria.

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Multiple Objectives

When considering several factors (like strength, weight, cost) in material selection, we need a way to balance their importance.

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Weighing Objectives

Assigning numerical values to different objectives (like strength, cost) to reflect their relative importance.

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What are the key criteria for ranking?

Selection criteria should include factors like feasibility, unknowns, and overall performance index of the materials.

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Check Feasibility

Evaluating whether a material is practically possible to manufacture, obtain, or use in the intended design.

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Unknown Factors

Potential uncertainties or unknown aspects about the material that need to be investigated before final selection

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Why might the top-ranking candidate not be chosen?

While a material might rank high on a performance index, it may not be suitable for the specific application or have practical limitations.

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Minimum Mass Design

Designing a structure to have the lowest possible weight while meeting performance requirements.

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Stiffness

A material's resistance to deformation under stress.

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Three-Point Bending

A common test method to determine a material's stiffness where a beam is supported at two points and a force is applied at the center.

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Deflection

The amount a beam bends under a load.

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Second Moment of Area

A geometrical property that describes a cross-section's resistance to bending. It's represented by 'I'.

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Free Variable

A variable in an equation that can be independently changed or eliminated to simplify an equation or solve for a specific parameter.

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Ski Core Material

The material used in the center of a ski to provide strength, flexibility, and damping.

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Cork Advantages

Cork for a ski core offers renewable resource, biodegradable, good reputation, and damping behavior.

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Soft Polymer Foam Advantages

Soft polymer foam offers fast production, any shape possible, and high throughput.

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Plywood Advantages

Plywood offers local production in CH, renewable resources, good reputation, and mitigation of wood imperfections through gluing.

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Cork Disadvantages

Cork can be more expensive and large sheets are less common.

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Soft Polymer Foam Disadvantages

Soft polymer foam is oil-based, not renewable, and oil is increasing in price

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Plywood Disadvantages

Plywood may have imperfections that require gluing for mitigation.

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Material Validation

The process of evaluating material choices and considering all relevant aspects like function, manufacturability, and sustainability.

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Ashby Chart

A graphical tool used to compare and select materials based on two key properties (e.g., strength and density).

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Material Selection

The process of choosing the right material for a specific application based on its properties and suitability.

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Why are multiple parameters important in material selection?

Considering only two parameters might not capture the full picture. Other factors like cost, availability, and environmental impact also play a significant role.

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Beam Deflection

The amount a beam bends under a load. It depends on the material's properties, geometry, and applied force.

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CFRP Composite

A strong and lightweight material often used in aerospace and automotive applications.

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Density

The mass of a material per unit volume.

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Stiffness (Young's Modulus)

A material's resistance to deformation under a load. A higher stiffness means less bending.

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Mass

The amount of matter in an object.

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Study Notes

Engineering Design and Material Selection

  • Lecture 11 focused on material selection
  • Key figures and lecturers included Kristina Shea and Tino Stankovic
  • Material selection strategies for design processes were discussed

Course Schedule

  • The course schedule outlines topics, case studies, quizzes, and lecturer assignments for each week
  • A different lecturer delivers each lecture
  • Different case studies are used each week

Learning Objectives

  • Understanding factors influencing material selection during design processes
  • Learning about Ashby charts and how to create and use them for material selection
  • Learning strategies for material selection and applying them to examples

Oxo Goodgrips Peeler

  • Material: Santoprene (a polymer that behaves like rubber)
  • Oval Handle: Ergonomically shaped for handgrip and comfort. Aesthetically popular at the time
  • Manufacturing: molding process for easier production
  • Counter-sunk Hole: Improved ergonomics for use, reduced cost by reducing material usage. Aesthetically improves appearance.
  • Fins: Enhance grip with fingers and thumb. Curve echoes handle shape for a seamless aesthetic. manufacturing considerations.

Challenge: Suitable Materials

  • Many materials are suitable, but selecting the best one presents a challenge.
  • Questions to consider about material selection:
    • How to choose from the many materials?
    • What is a helpful strategy?

When do we select materials? — Stages

  • The material selection process occurs at different stages of product development:
  • Phase 0: Planning
  • Phase 1: Concept Development
  • Phase 2: System-Level Design
  • Phase 3: Detail Design
  • Phase 4: Testing & Refinement
  • Phase 5: Production Ramp-Up
  •  Materials selection is an iterative process, often revisiting previous choices.

Material Selection Strategies – General Approach

  • The strategies include translation, screening, ranking, and validation
  • Translation: Understanding design requirements, objectives, and constraints.
  • Screening: Identifying viable materials that meet constraints, using attribute limits.
  • Ranking: Prioritizing materials based on performance measures that satisfy design objectives.
  • Validation: Investigating the suitability of top-ranked candidates through documentation and usage explorations.
  • The approach can be depicted in a flow chart. Multiple steps may be involved at different stages of product development.

Material Selection – General Approach – Additional Details

  • Design Requirements: Specifications that define how the product should operate.
  • Function: Defining what the product should do.
  • Objectives: Measurable goals like cost.
  • Constraints: Limitations like size or temperature resistance.

Material Selection Strategies – Computer-Aided Material Selection — General Approach

  • Computer-aided selection for vast materials can be helpful.
  • Specific software allows for any combination of selection criteria, including material properties such as density, price, mechanical properties, and thermal properties

One-Dimensional Material Selection

  • A method for selection using a single property (e.g. Young's modulus)

Two-Dimensional Material Selection - Ashby Charts

  • Graphic method comparing/contrasting material properties (e.g., Young's moduli and density)
  • Displays materials suitable for specific use cases
  • An approach to guide material selection, involving log scales for range and properties.

Two Dimensional Material Selection – Performance Index

  • A strategy for evaluating material properties using performance index and guidelines.

Two-Dimensional Material Selection – Log Scales

  • Using log scales for wider ranges allows for visualization of material properties to suit potential applications
  • Power functions can be shown graphically to illustrate properties

Example: Minimum Mass Design — Stiffness — Beam in Bending

  • Identify the parameters to be considered. The objective here is to minimize the mass of a beam.
  • Develop relevant equations for deflection and mass

Two-Dimensional Material Selection — Ashby Charts

  • Use of a 2D chart to plot contrasting/complementary material properties
  • Selecting feasible materials
  • Limiting material properties to guide selection.

Beyond 2D Material Selection

  • Need for multi-dimensional analysis
  • Computer aided material search
  • Material parameters
  • Parameters to optimize

Case Study: Ski Core

  • Requirements: Bending stiffness tuned to the skier, light weight, low CO2 footprint, and geometry constraints.
  • Objectives and constraints for which materials are suitable or feasible.

Step 1: Translation

  • Requirements for the ski core, including bending stiffness, dimensions, and material properties.

Step 2: Screening

  • Screening out materials that do not meet the yield strain or Young modulus constraints
  • Focus on materials that meet constraints. Materials can be grouped for easier handling and review.

Step 3: Ranking

  • Ranking various materials, based on different criteria and objectives
  • Comparing different materials considering cost, CO2 footprint and density.

Step 4: Validation

  • Validating the best materials in the selection process
  • Investigating the suitability of materials for use, based on various criteria, including manufacturability

Question: Which material would you choose?

  • Choice question involving cork, soft polymer foam, and plywood as potential options for ski core material.

Material Selection – Wrap Up

  • Material selection considers desired function, manufacturability, and sustainability in design processes.
  • Generalized material selection can narrow down the list of suitable materials using screening and ranking.

Exercise 11

  • Identifying the best materials suitable for objects like a diving board, a hatchet, or skateboards.

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Related Documents

Engineering Design and Material Selection Lecture 11 PDF

Description

Test your knowledge on material selection strategies and design principles. This quiz covers key steps in the material selection process and the criteria for evaluating materials for product design. Enhance your understanding of both aesthetic and ergonomic considerations in material choice.

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