IPS Case Study: Containment Ring Problem
Introduction: Working with the Innovation WorkBench (IWB) Software
The Innovation WorkBench (IWB) software implements a five- step process for solving inventive problems, as follows:
Step 1: Problem documentation and preliminary analysis using the Innovation Situation Questionnaire
Step 2: Problem modeling and formulation using the Problem Formulator
Step 3: Selection and prioritization of directions for solving the problem
Step 4: Development of solution concepts
Step 5: Evaluation of results and revealing/solving problems that might arise during implementation
Each of the above steps were carried out for the containment ring problem and are described below.
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Innovation Situation Questionnaire
The engineered system, which is designed to contain the fragments resulting from an impeller burst of a maximum- speed fan, consists of the following: a fan, fan shroud (which controls the direction of the air stream), and an armor-steel containment ring. The problem to be solved is that the ring is too heavy and must be reduced in weight by 50%.
2. Information about the system
2.1 System name
We can consider this problem with regard to the following systemic levels:
Containment ring
Fan
Air conditioning system
Aircraft
Testing of ring
For the ring, the problem is as follows: the ring must be strong to withstand the impact of the impeller fragments, and the ring should not be heavy.
For the fan, the problem is as follows: the impeller can burst, but fragments should not fly away.
For the air-conditioning system, the problem is as follows: the impeller can be broken, but the air should be conditioned.
For the aircraft, the problem is as follows: the impeller can burst, but neither people nor equipment should be harmed.
For testing the ring, the problem is as follows: the ring's ability to capture flying fragments should be tested, but it is difficult to move the heavy ring back and forth.
Idea # 1: Make the ring as an assembly made of light-weight parts that are easy to move for testing purposes.
We can influence two systemic levels: the ring and the fan assembly. Let's select the fan assembly as the system to be considered.
2.2 System structure
The fan assembly consists of the following elements:
fan
motor
shaft
motor support
containment ring
connectors or support to keep the ring
2.3 Functioning of the system
The primary useful function of the fan is to supply (i.e., move) air for the air conditioning system.
The fan rotates quickly and moves air. The air is conditioned so that the aircraft cabin can be supplied with conditioned air.
2.4 System environment
Other parts of the air conditioning system:
pipes
heat exchanger
airflow distributors
Other systems located nearby:
aircraft covering
equipment
Other system interacting with the fan and air conditioning system:
electrical power supply
air supply
exhaust air removal
vibration dampers
Conditions around the system: indoor conditions
3. Information about the problem situation
3.1 Problem that should be resolved
Reduce the weight of the ring by 50%.
The primary harmful function of the given system (the fan assembly) is that impeller fragments fly away if the impeller bursts.
3.2 Mechanism causing the problem
The containment ring must be strong to contain the flying fragments √ for this reason the ring is thick and, as a result, heavy.
The cause of an impeller burst is as follows: Rotation of the fan results in centrifugal forces that "pull" the parts of the impeller. The strength of the impeller material can be compromised by material defects and fatigue. As a result, the impeller can burst, causing the impeller fragments to fly off. Due to the high speed at which the fan rotates, the flying fragments carry high energy and can harm people and other parts of the aircraft.
2.3 Undesired consequences of unresolved problem
The high weight of the ring makes it difficult to carry out the routine tests required by the FAA.
The "dead weight" of the aircraft equipment is also high.
If the weight problem is resolved at the expense of the ring's strength, the result will be inadequate protection from the flying impeller fragments, which in turn can result in death and/or damage.
2.4 History of the problem
The increased requirements for conditioning the air are met using a higher velocity airflow, but this means that the rotational speed of the fan increases. As a result, an impeller burst becomes more probable and the danger from the flying fragments increases. Because the energy of the flying fragments is increased, the ring must be stronger. As a result, the ring is heavier.
Known attempts to reduce the ring thickness resulted in a reduction in strength.
Idea # 2: Provide high airflow with low rotational speed of the fan. Perhaps utilize several slow fans instead of one that rotates quickly.
2.5 Other systems in which a similar problem exists
Similar problems exist in many other areas where weight and mechanical strength are critical issues, as well as other systems for protection against flying parts. We do not have any information about how these problems have been addressed.
2.6 Other problems to be solved
Use an alternative method to contain the fragments.
Make the impeller unbreakable.
Others (see the problems on different systemic levels in the beginning of the Innovation Situation Questionnaire).
4. Ideal vision of solution
No containment ring is necessary.
An impeller burst is no longer possible.
5. Available resources
Substance resources
Material of containment ring
Material of fan impeller
Other objects around
Airflow
Field resources
Mechanical forces
Airflow energy
Electrical energy
Magnetic field (motor)
Space resources
Space inside the ring
Space outside the ring
Time resources
Time during which the fan is not operating
Time when the fan is operating
Time before the impeller bursts
Time after the impeller bursts
Informational resources:
No special resources
Functional resources
Rotation
5. Allowable changes to the system
Drastic changes are allowed.
Any reduction in strength is unacceptable.
6. Criteria for selecting solution concepts
Weight reduction of at least 30%
Cost increase of no more than 5%
About two weeks for new design
One year for implementation
(Withheld)
8. Project data
(Withheld)
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Problem Formulation
Situation model
Basic Directions for Innovation
Problem statement |
Pri-
ority |
Direction |
Preliminary ideas |
1. Find a way to eliminate, reduce, or prevent [the] (Ring is heavy) under the conditions of [the] (Ring is thick). |
1 |
Reduce weight or density Change the structure |
|
2. Find an alternative way to obtain [the] (Ring is thick) that offers the following: provides or enhances [the] (High mechanical strength), does not cause [the] (Ring is heavy). |
1 |
Reduce weight or density Change the structure |
|
3. Try to resolve the following contradiction: The useful factor [the] (Ring is thick) should be in place in order to provide or enhance [the] (High mechanical strength), and should not exist in order to avoid [the] (Ring is heavy). |
1 |
Resolve contradiction related to the ring thickness |
|
4. Find an alternative way to obtain [the] (High mechanical strength) that offers the following: provides or enhances [the] (Containing fragments), does not require [the] (Ring is thick). |
1 |
Improve mechanical strength |
|
5. Find an alternative way to obtain [the] (Containing fragments) that offers the following: eliminates, reduces, or prevents [the] (Fragments flying away), does not require [the] (High mechanical strength). |
2 |
Contain fragments with the weak ring |
Idea # 3: Utilize a "weak" ring that will absorb energy as it is destroyed |
6. Find a way to eliminate, reduce, or prevent [the] (Fragments flying away) in order to avoid [the] (Damage to the aircraft), under the conditions of [the] (Impeller burst). |
2 |
Stop fragments from flying |
|
7. Find a way to eliminate, reduce, or prevent [the] (Impeller burst) in order to avoid [the] (Fragments flying away), under the conditions of [the] (Centrifugal forces pull parts of impeller) and (Impeller's material is not strong enough). |
3 |
Prevent the burst |
|
8. Find a way to eliminate, reduce, or prevent [the] (Centrifugal forces pull parts of impeller) in order to avoid [the] (Impeller burst), under the conditions of [the] (Fan rotates quickly). |
3 |
Counteract centrifugal forces |
|
9. Find an alternative way to obtain [the] (Fan rotates quickly) that offers the following: provides or enhances [the] (Fan moves air), does not cause [the] (Centrifugal forces pull parts of impeller) and (High energy of fragments). |
Out of scope |
Alternative fan rotation |
|
10. Try to resolve the following contradiction: The useful factor [the] (Fan rotates quickly) should be in place in order to provide or enhance [the] (Fan moves air), and should not exist in order to avoid [the] (Centrifugal forces pull parts of impeller) and (High energy of fragments). |
Out of scope |
Resolve contradiction related to the speed of fan rotation |
|
11. Consider transitioning to the next generation of the system that will provide [the] (Fan moves air) in a more effective way and/or will be free of existing problems. |
Out of scope |
|
|
12. Find an alternative way to obtain [the] (Fan moves air) that does not require [the] (Fan rotates quickly). |
Out of scope |
Move air without rotation |
|
13. Find a way to eliminate, reduce, or prevent [the] (Damage to the aircraft) under the conditions of [the] (Fragments flying away) and (High energy of fragments). |
Out of scope |
Protect aircraft from fragments |
|
14. Consider transitioning to the next generation of the system that will provide [the] (Test convenience) in a more effective way and/or will be free of existing problems. |
Out of scope |
|
|
15. Find an alternative way to obtain [the] (Test convenience) that is not influenced by [the] (Ring is heavy). |
1 |
Improve test convenience |
Idea # 4: Perform testing without removing the ring |
16. Find a way to eliminate, reduce, or prevent [the] (High energy of fragments) in order to avoid [the] (Damage to the aircraft), under the conditions of [the] (Fan rotates quickly). |
1 |
Reduce energy of fragments |
Idea # 5: Reduce the mass of the fragments to reduce damage |
17. Find a way to eliminate, reduce, or prevent [the] (Material defects) in order to avoid [the] (Impeller's material is not strong enough). |
3 |
Screen material |
|
18. Find a way to eliminate, reduce, or prevent [the] (Impeller's material is not strong enough) in order to avoid [the] (Impeller burst), under the conditions of [the] (Material defects). |
3 |
Improve strength of impeller |
|
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Prioritize Directions and Generate Preliminary Ideas
The following preliminary ideas resulted from the direct analysis of the Basic Directions:
Idea # 3: Utilize a "weak" ring that will absorb energy as it is destroyed
Idea # 4: Perform testing without removing the ring
Idea # 5: Reduce the mass of the fragments to reduce damage
Directions selected for further consideration
Selected Basic Directions Selected Refined Directions
Selected Basic Directions |
Selected Refined Directions |
1. Find a way to eliminate, reduce, or prevent [the] (Ring is heavy) under the conditions of [the] (Ring is thick). |
Reduce weight |
4. Find an alternative way to obtain [the] (High mechanical strength) that offers the following: provides or enhances [the] (Containing fragments), does not require [the] (Ring is thick). |
4.1. Improve the useful factor (High mechanical strength). |
3. Try to resolve the following contradiction: The useful factor [the] (Ring is thick) should be in place in order to provide or enhance [the] (High mechanical strength), and should not exist in order to avoid [the] (Ring is heavy). |
3.1. Apply separation principles to satisfy contradictory requirements related to [the] (Ring is thick). |
5. Find an alternative way to obtain [the] (Containing fragments) that offers the following: eliminates, reduces, or prevents [the] (Fragments flying away), does not require [the] (High mechanical strength). |
5.3. Increase effectiveness of the useful action of [the] (Containing fragments). |
7. Find a way to eliminate, reduce, or prevent [the] (Impeller burst) in order to avoid [the] (Fragments flying away), under the conditions of [the] (Centrifugal forces pull parts of impeller) and (Impeller's material is not strong enough). |
-Protect from fire or explosion
-Reduce deformation, displacement, shock, vibration or destruction |
15. Find an alternative way to obtain [the] (Test convenience) that is not influenced by [the] (Ring is heavy). |
15.1. Improve the useful factor (Test convenience). |
Direction 1: Reduce weight
Operator: Abandon symmetry
Idea # 6: Vary the thickness of the ring tube. Reduce the thickness where permissible.
Operator: Reduce the weight of individual parts
Operator: Strengthen individual parts
Auxiliary Operator: Substance modification
Auxiliary Operator: Generate mechanical stress
Idea # 7: Generate mechanical stress. For example, use additional rings which have been pressure- fitted to create a force directed toward the inside the ring.
Auxiliary Operator: Heat treatment
Idea # 8: Use thermal treatment to harden the ring material.
Auxiliary Operator: Introduce additives
Idea # 9: Use of special threads, such as in bullet protection vests.
Operator: Apply inflatable constructions
Idea # 10: Replace the ring with the airbag inflated by the impeller burst.
Direction 4.1: Improve the useful factor (mechanical strength)
Operator: Transform the shape of the object
Idea # 11: Make a thin ring, which has reinforcing ribs (see figure, below). If the ribs are placed on the internal surface of the ring, flying fragments will lose a large amount of their energy smashing into the ribs.
Idea # 12: Make the ring corrugated in two planes.
Auxiliary Operator: Create a shape conforming to expected wear
Idea # 13: Find where the rings usually break and reinforce these places.
Auxiliary Operator: Preliminary anti-action
Idea # 14: Internal ribs with sharp edges can counteract flying fragments breaking them into smaller pieces.
Operator: Transform an object's micro-structure
Auxiliary Operator: Modify part of a substance
See idea # 8.
Auxiliary Operator: Substitute for a part of substance
Idea # 15: Use a multi-layer ring: additional strengthening rings, rings having different hardness and elasticity, rings which have a gap in-between them filled with an energy- absorbing material. (See figure, below.)
Idea # 16: Make the ring out of separate layers so cracks, which develop inside, won't spread.
Operator: Integration into a poly-system
See idea # 15.
Operator: Introduce a strengthening element
Idea # 17: Use metal concrete or other composite materials
Operator: Anti-loading
Auxiliary Operator: Use pre-stressed constructions
Idea # 18: Create inner stresses inside the ring: This can be done, for example, using wiring, banding, double ring structure, etc.
Direction 3.1: Apply separation principles to satisfy contradictory requirements related to [the] (Ring is thick)
Operator: Separate opposite requirements in space
See ideas ## 5, 11, 13, 15: Ring with variable thickness, ribs; multi-layer ring.
Operator: Separate requirements in time
See idea # 10: Replace the ring with the airbag inflated by the impeller burst.
Operator: Separate opposite requirements between parts and the whole object
See idea # 1: Make the ring as an assembly from light parts that are easy to move for testing.
Operator: Separate requirements via changing conditions
Idea # 19: Change the ring thickness or strength or other containing capabilities at the moment of impeller burst.
Direction 5.3: Increase effectiveness of the useful action of [the] (containing fragments)
Operator: Intensify a field
Auxiliary Operator: Substances as energy accumulators
Idea # 20: Explode the ring in the moment of the impeller burst. Use the explosion wave to create a counteracting force.
Operator: Concentrate energy
Idea # 21: Disintegrate the fragments.
Idea # 22: Utilize special geometrical shapes to create traps for the fragments. For example, make the ring in the form of spring.
Operator: Introduce an additional field
Idea # 23: Create a combination of pressurized air and liquid to counteract fragments.
Operator: Substitute a field with a more effective one
See idea # 20: Counteracting explosion.
Operator: "Make a road"
Idea # 24: Create a safe pathway for fragments.
Idea # 25: Introduce strong fibers in the impeller blades that are capable to hold fragments after blades crash.
Direction 7a: Protect against fire or explosion
Operator: Introduce an insulating substance
Idea # 26: Use foam or foam-like material to absorb energy. Apparently, we need special type of foam like metal foam. We can also consider other fillings that can absorb energy (see also idea # 3).
Operator: Counteraction by means of a similar action
See idea # 20: Counteracting explosion.
Direction 7b: Reduce destruction
Operator: Counteraction by means of a similar action
See ideas ## 20, 21: counteracting explosion, disintegrating fragments
Operator: Anti-action
Consideration # 1: We can apply all ideas obtained for improving mechanical strength of the ring to the impeller blades.
Operator: Draw off an undesired action
See idea # 26: absorb the energy of fragments
Operator: Local slackening of an action
Idea # 27: Define less dangerous directions and redirect fragments to these directions.
Idea # 28: Distributing the harmful energy between more fragments (see also ideas # 7 and 21: reducing energy /mass of fragments)
Operator: Slacken an action (weaken an undesired action by prolonging it)
Idea # 29: Create a special pathway (spiral) to trap the fragments and to reduce their energy while traveling through the spiral route (see ideas ## 22 and 24). Also, see idea # 26: absorb the energy.
Direction 15.1: Improve the useful factor (Test convenience)
(NOTE: This direction has been addressed in a limited fashion as we do not have detailed information about the test procedure.)
Operator: Make an object dismountable
See idea # 1: Make the ring as an assembly from light parts that are easy to move for testing.
Operator: Apply disposable objects
Idea # 30: Disposable ring - consider that the ring will be destroyed while absorbing all the energy of the fragments (similar to idea # 3).
Operator: Move a heavy object
Idea # 31: Consider various types of support while transporting the ring.
Operator: "Retain the available"
Idea # 32: Learn in detail the process of transportation and look for the ways to reduce the number of lifting of the ring.
List and categorize all preliminary ideas
Idea # 1: Make the ring as an assembly made of light-weight parts that are easy to move for testing purposes.
Idea # 2: Provide high airflow with low rotational speed of the fan. Perhaps utilize several slow fans instead of one that rotates quickly.
Idea # 3: Utilize a "weak" ring that will absorb energy as it is destroyed.
Idea # 4: Perform testing without removing the ring.
Idea # 5: Reduce the mass of the fragments to reduce damage.
Idea # 6: Vary the thickness of the ring tube, reducing the thickness where permissible.
Idea # 7: Introduce preliminary stress. For example, use additional rings which have been pressure- fitted to create a force directed toward the inside of the ring.
Idea # 8: Use thermal treatment to harden the ring material.
Idea # 9: Use special reinforcing threads (fibers) such as those found in bullet-proof vests.
Idea # 10: Replace the ring with an airbag that inflates when the impeller bursts.
Idea # 11. Make a thin ring that has reinforcing ribs. If the ribs are placed on the internal surface of the ring, flying fragments will lose much of their energy smashing into the ribs.
Idea # 12: Make the ring corrugated in two planes.
Idea # 13: Determine where the ring usually breaks and reinforce those places.
Idea # 14: Internal ribs with sharp edges can counteract flying fragments, breaking them into smaller pieces.
Idea # 15: Use a multi-layer ring: additional strengthening rings, rings having different hardness and elasticity, rings which have a gap in between them, filling the gap with an energy-absorbing material.
Idea # 16: Make the ring out of separate layers so that if cracks develop inside they will not spread.
Idea # 17: Use metal-concrete or some other composite material.
Idea # 18: Create inner stresses inside the ring: This can be done using wiring, banding, double ring structure, etc.
Idea # 19. Change the ring thickness or strength or other containment capabilities the moment the impeller bursts.
Idea # 20. Explode the ring the moment the impeller bursts. Use the explosion wave to create a counteracting force.
Idea # 21. Disintegrate the fragments.
Idea # 22. Utilize special geometrical shapes to create traps for the fragments. For example, make the ring in the form of spring.
Idea # 23. Create a combination of pressurized air and liquid to counteract the fragments.
Idea # 24: Create a safe pathway for the fragments.
Idea # 25. Introduce strong fibers in the impeller blades that are capable of holding the fragments after the impeller bursts.
Idea # 26. Use foam or foam-like material to absorb energy. Apparently, we need a special type of foam such as metal foam. We can also consider other fillings that can absorb energy (see idea # 3).
Idea # 27. Define the least dangerous directions and redirect the fragments in these directions.
Idea # 28. Distribute the harmful energy between more of the fragments (see also ideas # 7 and 21: reducing energy/mass of the fragments).
Idea # 29. Create a special pathway (spiral) to trap the fragments and to reduce their energy while traveling through the spiral route (see ideas # 22 and 24). Also, see idea # 26: absorb the energy.
Idea # 30. Disposable ring - consider that the ring will be destroyed while absorbing all the energy of the fragments (similar to idea # 3).
Idea # 31. Consider various types of support while transporting the ring.
Idea # 32. Learn the details of the transporting process and look for the ways to reduce the number of lifting.
We can categorize the obtained ideas into the following groups:
1. Strengthening the ring via:
a) changing the ring material structure:
creating inner stresses (wiring, banding, press-fit) (# 18, 7)
introducing special reinforcing threads (fibers), using metal- concrete or other composite materials (# 9, 17, 25)
special thermal treatment for hardening the ring material (# 8)
using a multi-layer ring with layers with different properties (elasticity, hardness, gaps filled with energy- absorbing materials) (# 15)
b) changing the ring's shape:
vary the ring thickness to best accommodate the situation (# 6,13)
create various reinforcing ribs (# 11)
use two-plane corrugations (# 12)
2. Increasing the ring's energy-absorbing properties via
a) changing the material structure:
using foam and/or foam-like materials (metal foam, honeycomb, wiring, brushes) (# 3, 23, 26, 30)
using a multi-layer ring with layers capable of moving relative to one another to absorb extra energy
b) changing the ring's shape:
spiral or other traps that can slow down the fragments (# 22)
3. Reducing the mass/energy of the flying fragments to reduce damage and allow the ring's mechanical strength to be lowered via
changing the ring's material structure to make it capable of breaking into smaller pieces (# 5, 21, 28)
introduce ribs with sharp edges capable of breaking fragments into smaller pieces (# 11, 14)
4. Improve testing convenience, including:
perform the test without removing the ring (# 4)
make the ring dismountable and transport parts of the ring rather than the whole thing (# 1)
consider various types of special support during ring transport (# 31)
5. Strengthen the impeller blades to eliminate the need for the ring (# 25)
6. Define or create a safe pathway for the fragments (# 24, 27, 29)
7. Change the principle of operation of the ring, including:
replace the ring with an airbag that inflates the moment the impeller bursts (# 10) or change its thickness (# 19)
explode the ring to create a counteracting force (# 20) and/or break the fragments into smaller pieces
8. Replace the impeller with a safer method of providing air (# 2)
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Develop Concepts
Combine ideas into concepts
Combine ideas that perform the same function in different ways
Step 1. Select two ideas that resolve the same sub-problem in different ways.
Idea # 17 (Use metal concrete or other composite materials) and idea # 11 (make a thin ring with reinforcing ribs) provide the same function (strengthening) in different ways √ changing structure (# 17) and changing shape (# 11).
Step 2. Compare these ideas; each has its own advantages.
Idea # 11 is preferable from the main function point of view because it can provide greater strength. However, it is not easy to make ribs from the steel. The advantage of idea # 17 is that composite materials are easy to shape.
Step 3. Consider the idea that has better functional features as the "source of resources"; the other idea is the "recipient of resources."
We select idea # 11 as the "source of resources"
Idea # 17 is the "recipient of resources"
Step 4. Determine the elements that provide better functionality of the "source" idea.
The element providing better functionality is a steel tube.
Steps 5-7. Apply these elements to the "recipient."
We can combine two ideas having a steel tube with ribs made from a composite material.
Apply Lines of Evolution to further improve your concepts
A substantial number of the obtained ideas have already included features recommended by most of the patterns/lines above. For example, the idea of a multi- layer ring is in accordance with the patterns Building bi- and poly- systems and Segmentation; the idea of using composite materials fits the pattern Developing a substance's structure; ideas related to replacing the ring with an airbag or exploding the ring fit the pattern of Dynamization.
It might still be interesting, however, to consider the set of Operators/Lines entitled increasing controllability.
Operator: Introduce an additive to increase process controllability
Operator: Introduce a controlled section
Operator: Self-control
The Operators above allow us to further develop idea # 20 (explosive ring). A controlled section (detonator) and additives (explosives) should be placed in the light tube. The first fragment that will reach the tube will activate the detonator (self-control).
Evaluate Results
Meet criteria for evaluating concepts
The following ideas were selected:
For short-term: Multi-layer ring; ring with ribs.
For mid-term: Explosive ring.
For long-term: Blades with fibers (wire) inside to keep pieces in place.
The short-term idea of utilizing a multi-layer ring creates a secondary problem - the increased cost associated with manufacturing the different layers and with the final assembly of the ring. We therefore have a secondary problem - reduce cost.
Idealization
Exclude auxiliary functions
Operator: Exclude preliminary operations (functions)
Idea # 33: Instead of manufacturing several layers and assembling them later, use surface hardening of the internal and external surfaces of the ring. Hardening the inner surface will allow the ring to better counteract the fragments. Hardening the outer surface can create additional inner stresses that in turn increase the ring's overall strength. Together, these measures should allow the weight of the ring to be reduced without sacrificing its containment capabilities.
Reveal and prevent potential failures
7. Consider potentially dangerous moments/periods of time during implementation.
Idea # 34: According to the checklist, testing the ring can be dangerous itself - for example, reducing the ring's strength can later produce a ring failure. To avoid this problem, it might be preferable to replace the current test procedure with one that utilizes ultrasound, acoustic emission or other "intro- vision" technologies.
Plan the implementation
The following ideas were suggested for testing:
For the short-term: Ring with hardened surfaces; ring with ribs.
For the mid-term: Explosive ring.
For the long-term: Blades with fibers (wire) inside to keep the fragments in place.
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