MS-ETS1-1: Design Constraints and Impacts

MS-ETS1-1
Design Constraints and Impacts


Middle School

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Learning Objectives

• Define the specific criteria and constraints of a design problem with accuracy.

• Identify the system, its boundaries, and the stakeholders involved in an engineering problem.

• Explain how science, society, or the environment can limit a potential design solution.

• Analyze how engineers learn from past failures to improve their designs and solutions.

Key Vocabulary

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Criterion

A criterion is a standard or rule used to judge or measure the success of a design solution.

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Constraint

A constraint is a limitation or restriction, such as time or materials, in the design process.

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Design Problem

A design problem is a specific challenge or need that requires a new solution to be created.

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Environmental Impact

The environmental impact is the effect a design solution has on the natural world and its ecosystems.

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Stakeholder

A stakeholder is any person or group who is affected by the outcome of a design solution.

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System Boundary

A system boundary defines what is included within a problem and what is considered outside the problem.

Key Vocabulary

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Impulse

Impulse is the force applied to an object over a period of time to change its momentum.

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Crumple Zones

Crumple zones are special areas of a car designed to crush and absorb impact force during a collision.

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Prototype

A prototype is an early, functional model of a product that is built to test out a concept.

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Acoustic Engineer

An acoustic engineer is a specialist who studies the science of sound and its resulting vibrations on objects.

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Oscillation

Oscillation describes a repeating, back-and-forth movement that follows a consistent wave-like pattern over time.

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Defining an Engineering Problem

• The first step is to define the design problem and its stakeholders.

• Engineers establish system boundaries to clarify what is part of the problem.

• They must consider all societal and environmental impacts of their proposed solutions.

• A clearly defined problem is much more likely to be solved successfully.

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Multiple Choice

What is the first step in the engineering design process?

• To clearly define the design problem and its stakeholders.

• To begin building the first version of the solution.

• To select the cheapest materials available for construction.

• To market the proposed solution to the public.

Multiple Choice

What is the primary function of establishing system boundaries when defining an engineering problem?

• To make the problem seem more complex.

• To ignore the needs of the stakeholders.

• To focus only on the environmental impacts.

• To clarify what is part of the problem and what is not.

Multiple Choice

An engineering team designs a new factory without studying its potential effects on local air quality or traffic. Based on the principles of problem definition, what is a likely outcome?

• The project will be a guaranteed success because the problem was simple.

• The project may fail because key factors like environmental and societal impacts were not considered.

• The project will be finished ahead of schedule.

• The project will not require any further planning.

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Failure & Redesign: The Tacoma Narrows Bridge

The Failure

• The first bridge used a shallow, solid frame to reduce costs, a major design constraint for stakeholders.

• Wind caused the bridge to move in a repeating wave-like pattern, a scientific principle called oscillation.

• A lack of understanding of aerodynamics at the time ultimately led to the bridge’s collapse.

The Redesign

• The key criterion for the new design was to allow wind to easily pass through it.

• Engineers used prototypes to test a new open-frame design that could withstand the windy environmental conditions.

• This failure provided valuable lessons that significantly advanced the field of wind engineering for bridges.

Multiple Choice

What is the scientific principle that describes a repeating, wave-like pattern of movement, such as the one that affected the first Tacoma Narrows Bridge?

• Oscillation

• Aerodynamics

• Redesign

• Constraint

Multiple Choice

How did the redesigned Tacoma Narrows Bridge address the failure of the original structure?

• The redesigned bridge had an open frame to allow wind to pass through, while the original had a solid frame that blocked it.

• The redesigned bridge was built to be much heavier and more solid than the original.

• The original bridge was tested with prototypes, while the redesigned bridge was not.

• The original bridge was designed for windy conditions, while the redesigned bridge was not.

Multiple Choice

Based on the information about the failure and redesign of the Tacoma Narrows Bridge, what was the most important lesson for the field of wind engineering?

• Environmental forces like wind must be a primary consideration in bridge design, not just cost.

• Using shallow, solid frames is the most cost-effective way to build bridges.

• Bridge failures are always caused by a single, easily identifiable error.

• Prototypes are not useful for testing the effects of environmental conditions on structures.

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What is Acoustic Engineering?

• Acoustic engineers work to control sound, like reducing echoes or blocking unwanted noise.

• Stakeholders are people affected, like students in a library or nearby residents.

• They must balance constraints such as the material's cost, weight, and thickness.

• They aim to solve societal issues like noise pollution while ensuring safety.

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Multiple Choice

What is the main purpose of acoustic engineering?

• To control sound, such as reducing echoes or blocking unwanted noise.

• To identify the people who are affected by noise pollution.

• To measure the cost, weight, and thickness of building materials.

• To solve societal issues while ignoring safety concerns.

Multiple Choice

Why must an acoustic engineer consider both stakeholders and constraints when developing a solution?

• They must balance the needs of the people affected with practical limits like cost and materials.

• The stakeholders are the only ones who decide which materials to use.

• The main goal is to choose the heaviest and thickest materials possible.

• Societal issues like noise pollution are more important than project costs.

Multiple Choice

A library near a busy construction site needs to reduce noise for its patrons but has a very limited budget. What is the most likely recommendation an acoustic engineer would make?

• Recommend installing thick, sound-absorbing panels made from a cost-effective material.

• Suggest rebuilding the library using the most expensive soundproof materials.

• Advise the library to close until the construction project is finished.

• Place thin, decorative curtains over the windows to block the view.

Engineering for Impact Safety

• Engineers increase impact time to reduce the force on passengers during a collision.

• Crumple zones absorb impact energy, protecting the rigid passenger safety compartment.

• Helmets use a hard shell and soft foam to reduce impact forces on the head.

Multiple Choice

How do the crumple zones of a car protect the passengers inside the safety compartment?

• By making the passenger compartment heavier

• By deflecting the force to other parts of the car

• By absorbing impact energy and increasing the collision time

• By creating a rigid barrier that stops the impact

Multiple Choice

A helmet has both a hard outer shell and a soft foam liner. Which statement best explains why the soft foam is critical for reducing impact forces on the head?

• The foam is designed to compress, which increases the time of the impact and absorbs energy.

• The hard shell is the only part that protects the head from injury.

• The foam makes the helmet lighter and more comfortable to wear.

• The hard shell shatters on impact, and the foam holds it together.

Multiple Choice

What is the primary purpose of engineering safety features like crumple zones and helmets?

• To decrease the amount of force transferred during an impact

• To make a vehicle travel faster

• To stop the vehicle instantly upon collision

• To increase the strength of the entire vehicle body

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Common Misconceptions

Misconception	Correction
The only constraints in engineering are time and money.	Constraints also include science, safety, environment, and stakeholder needs.
The strongest and most solid bridges are always the safest.	Bridge design must suit its environment; sometimes flexibility is safer.
Engineering is about building things correctly the first time.	Engineering involves testing, learning from failures, and refining designs.

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Summary

• A design problem must identify stakeholders, needs, criteria, and constraints.

• Studying engineering failures is essential for improving future designs.

• Safety features like crumple zones reduce impact forces using scientific principles.

• Engineers use prototypes to test solutions against criteria and constraints.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4