|
Containment
Ring Problem
A comparative case study using the Contradiction Table,
Improver software, and the Innovation WorkBench (IWB) software[1]
NOTE: The IWB portion of
this case study appears in a separate
document.
Boris Zlotin, Alla Zusman,
and Len Kaplan
CONTENTS:
Introduction
– Problem description
– Selection of tools
– Main principle underlying the development
of a TRIZ case study
Working with the Contradiction Table and
40 Innovation Principles
– Results
Working with the Improver software
– Developing concepts
– Evaluating results
– Enhancing a selected idea
– Solving secondary problems
– Reformulating the initial problem and
obtaining new ideas
– Final list of concepts
Conclusion
NOTES
Introduction
The variety of TRIZ
tools available provides considerable flexibility in learning and utilizing
TRIZ, but also creates confusion in the minds of new and potential TRIZ
users. What are the differences between the various tools? Which tool
(or tools) should be learned first? To which type of problem should each
tool be applied?
Indeed, each tool
has its own advantages and limitations, and in an effort to provide clear
and credible answers to these questions, the study described herein was
undertaken.[2]
As we have mentioned
in previous publications,[3] TRIZ tools can be divided
into two groups:
Analytical tools
that help to define, formulate and model a problem, and include:
- ARIZ
- Substance-Field
Analysis
- Innovation Situation
Questionnaire® (ISQ)[4]
- Problem Formulator™
Knowledge-base
tools, derived from the accumulated knowledge of the human innovative
experience, and organized and structured to provide users with the highest
degree of problem-solving value. These include:
- Patterns/Lines
of Technological Evolution
- 40 Innovation
Principles (in conjunction with the Contradiction Table)
- Separation Principles
- 76 Standard Solutions
- Innovation Guide
("Effects")
- Selected Innovation
Examples
- System of Operators[5]
To demonstrate how the
various tools can be used and what kind of results can be achieved, we applied
each tool to the same "real life" problem. We selected a problem
concerning a Containment Ring, for the following reasons:
-
This problem was
submitted to us by our first American customer to test the capabilities
of TRIZ
-
It had been translated
into Russian and sent to several dozen TRIZ specialists in Russia,
Israel and the United States
-
Over 100 solution
ideas were obtained from various TRIZ specialists[6]
-
Over 80% of the
solution ideas were fairly consistent
-
A patent application
involving one of the solution ideas was filed.
Problem
description
An armor-steel containment
ring is designed to contain the fragments from an impeller burst of
a maximum speed fan. The system consists of the fan, a fan shroud (which
controls the direction of the air stream), and the containment ring (see
Figure 1). The problem is this: the containment ring is too heavy, and
must be reduced in weight by 50%.
Selection
of tools
The "map"
shown below was used to select the appropriate tools, depending on the
type of problem statement (in terms of parameter, functions, contradictions,
etc.).
As the
problem is stated in terms of a particular parameter (weight reduction)
and contains a hidden technical contradiction[7],
the following tools were selected:
- Contradiction
Table and 40 Innovation Principles
- System of Operators
The following tools
were excluded from consideration:
- Su-Field Analysis[8]
- 76 Standard Solutions
- ARIZ[9]
- Separation Principles[10]
As mentioned earlier,
the System of Operators is a complex, net-like tool containing numerous
internal links – thus, it can be fully utilized only in a software environment.
We selected the following Ideation software tools, both of which incorporate
the System of Operators:
The Improver[11]
contains an abbreviated version of the System of Operators. The Improver
is designed to be used to improve typical technical parameters of a product/process.
Weight is one such parameter, making the Improver a suitable tool for
the containment ring problem.
The Innovation
WorkBench[12] is a professional problem-solving
software product that incorporates a comprehensive set of tools, including:
- Innovation Situation
Questionnaire (ISQ)
- Problem Formulator
- System of Operators
- Innovation Guide
- Selected Innovation
Examples
Main
principle underlying the development of a TRIZ case study
It is widely known
among TRIZ professionals that success in problem solving is dependent
on the following components:
-
TRIZ Methodology/Philosophy
(M)
-
TRIZ tools (T)
-
Professional knowledge(PKN)
and expertise in the area the problem is related to
-
Personal capabilities
(PC) of the problem-solver, including motivation, level
of natural creativity, computer literacy, persistence, etc.
The above components
can be combined into the following equation:
S
= PC x PKN x (1+M) x (1+T)
Where "S"
is Success.
In our experience
teaching TRIZ, we have witnessed various combinations of the above components
– where, for example, natural creativity or persistence can compensate
for the lack of TRIZ knowledge, or vice versa. This fact has been demonstrated
by a phenomenon well-known in the TRIZ community, where an experienced
TRIZ professional finds a solution to a problem within the first steps
of ARIZ, while students or less experienced professionals must complete
nearly all of the steps before arriving at a solution.
Obviously, in a teaching
environment – as well as for the purposes of this comparison – we want
to exclude the influence of PC and PKN and focus
instead on the methodology. For this reason we have established and complied
with the following main principle in the development of educational case
studies and in teaching TRIZ students:
Direct and minimal
result: The result of each step offered by the methodology and
its tools should be directly and clearly derived from the step recommendation
or other TRIZ statement/information. In other words, an idea should be
obviously prompted by a formulated problem statement, an Operator, Guide
recommendation, or Illustration – and not the result of a remote association
or from the engineering elaboration of an experienced TRIZ professional.
Excluding the influence
of PC and PKN is no easy task, nonetheless, we have
tried to do just that in the containment ring case study.
Working
with the Contradiction Table and 40 Innovation Principles
Selected feature to
improve: Weight of moving object
Degraded attribute:
Strength
The following Innovation
Principles are recommended for trying to eliminate the above Technical
Contradiction.
28. Replacement
of a mechanical system
27. Inexpensive,
short-lived object for expensive, durable one
18. Mechanical
vibration
40. Composite
materials
In addition, the following
pairs of parameters can be considered:
Selected feature to
improve: Weight of moving object
Degraded attribute:
Reliability
Principles recommended:
3. Local conditions
11. Cushion in
advance
1. Segmentation
27. Inexpensive,
short-lived object for expensive, durable one
Selected feature to
improve: Weight of moving object
Degraded attribute:
Harmful factors acting on object
Principles recommended:
22. Convert
harm into benefit
21. Rushing
through
18. Mechanical
vibration
27. Disposable
object (substitute an inexpensive, short-lived object for an expensive,
durable one)
Altogether we have
obtained nine principles. Each has been considered in turn, yielding the
following results:
28. Replacement
of a mechanical system
a. Replace
a mechanical system by an optical, acoustical or olfactory (odor)
system
b. Use an electrical,
magnetic or electromagnetic field for interaction with the object
c. Replace
fields, for instance:
1. Stationary
fields with moving fields
2. Fixed
fields with those which change in time
3. Random
fields with structured fields
d. Use a field
in conjunction with ferromagnetic particles
IDEA
#1: Apply a magnetic field to contain the fragments.
27. Substitute
an inexpensive, short-lived object for an expensive, durable one (Disposable
object)
Replace an
expensive object by a collection of inexpensive ones, forgoing certain
properties (e.g., longevity).
IDEA
#2: Use a disposable ring that will be destroyed while absorbing the
energy of the fragments.
18. Mechanical
vibration
a. Set an object
into oscillation
b. If oscillation
exists, increase its frequency, even to ultrasonic
c. Use the
resonant frequency
d. Instead
of mechanical vibration, use piezo-vibrators
e. Use ultrasonic
vibration in conjunction with an electromagnetic field
No ideas.
40. Composite
materials
Replace a homogeneous
material with a composite one
Example: Military
aircraft wings are made of composites of plastics and carbon fibers
for high strength and low weight.
IDEA
#3: Make the ring from a composite material.
3. Local conditions
a. Transition
from a homogeneous structure of an object or outside environment/action
to a heterogeneous structure
b. Have different
parts of the object carry out different functions
c. Place each
part of the object under conditions most favorable for its operation
Example: To
combat dust in coal mines, a fine, cone-shaped mist of water is applied
to the working parts of the drilling and
loading machinery. The smaller the droplets, the greater the effect
in combating dust – the fine mist hinders the work, however. The solution
is to develop a layer of coarse mist around the cone of fine mist.
IDEA
#4: Use a ring that has a heterogeneous structure.
11. Cushion
in advance
Compensate
for the relatively low reliability of an object by countermeasures
taken in advance.
Example: Merchandise
is magnetized to deter shoplifting.
IDEA
#5: Consider using additional protection from flying fragments should
the reliability of the ring be insufficient.
1. Segmentation
a. Divide an
object into independent parts
b. Make an
object sectional
c. Increase
the degree of an object’s segmentation
Example: Sectional
furniture, modular computer components, folding wooden ruler
IDEA
#6: Use a multi-layer ring containing additional strengthening rings
of different hardness and elasticity.
22. Convert
harm into benefit
a. Utilize
harmful factors or environmental effects to obtain a positive effect
b. Remove a
harmful factor by combining it with another harmful factor
c. Increase
the amount of harmful action until it ceases to be harmful
Example: When
using high-frequency current to heat metal, it was found that only
the outer layer became hot. This negative effect was later used for
surface heat-treating.
No ideas.
21. Rushing
through
Perform harmful
or hazardous operations at very high speed.
Example: A
cutter for thin-walled plastic tubes prevents tube deformation during
cutting by running at a very high speed (i.e., the cut is made before
the tube has a chance to deform).
No ideas.
Results
The following ideas
(shown in order of feasibility) resulted from considering the above Principles:
-
Make the ring
from a composite material.
-
Use a multi-layer
ring containing additional strengthening rings of different hardness
and elasticity.
-
Use a ring that
has a heterogeneous structure.
-
Additional protection
from flying fragments if reliability is insufficient.
-
Use a disposable
ring that will be destroyed while absorbing the energy of the fragments.
-
Apply a magnetic
field to contain the fragments.
It is important to
mention that most of these ideas are general in nature and require further
specification.
Working
with the Improver software
Developing
concepts
The following menus
were offered by the software:
We selected Improve
a product:
Our main problem is
Reduce weight. The following Operators are recommended:
Additional typical
problems and recommended Operators appear in the table below:
|
Typical
problem
|
Recommended
Operators
|
|
Improve mechanical
strength
|
- Transform
an object's shape
- Transform
an object's structure
- Introduce
a strengthening element
- Pre-load
an object
|
|
Improve reliability
|
- Duplicate
critical elements
- Apply the
module principle
- Substitute
for a set of simple objects
- Continuous
restoration of a damaged part
- State stabilization
|
|
Idealization
|
- Exclude auxiliary
functions
- Exclude elements
- Change the
principle of operation
- Use highly
integrated components
- Self-service
|
Upon considering the
recommended Operators (and their associated Illustrations) the following
results were obtained:
OPERATOR: Abandon
symmetry
IDEA #1: Vary
the thickness of the ring tube, reducing the thickness where permissible.
OPERATOR: Reduce
the weight of individual parts
IDEA
#2: Reduce
the energy of the fragments by reducing their weight (i.e., "help"
the impeller break into smaller pieces). The ring is therefore not required
to be as strong, and can be made lighter as a result.
In the interest of
brevity, we will provide text extracted from the software rather than
screen shots.
|
OPERATOR: Strengthen
individual parts
Consider
strengthening those parts that bear the main load and reducing
the weight of parts that do not bear the main load.
ILLUSTRATION:
Containers for jettisoning loads
When an
object is jettisoned from an aircraft, the container – as well
as its contents – are susceptible to damage from the subsequent
impact. Even if the container is rigid enough to withstand the
impact, damage to the contents can result when they strikes the
inner walls of the container.
Strengthen
the part that bears the main load: The outer layer of the
container can be made of a light, rigid material that will be
destroyed when it hits the ground, absorbing the energy of the
impact. Reduce the weight of the part that does not bear
the main load: The inner layer can be constructed of a flexible
material, which resists puncture and breakage.
The result:
The weight of the container is reduced and the contents protected
from damage.
This design
reproduces an idea used with low-flying attack aircraft during
World War II. Double armor was used in these aircraft: the outer
layer was made of thin, breakable steel that absorbed or deflected
the energy of a bullet; the inner layer was made of steel with
a high plastic content which deformed, but was not punctured,
upon impact.
|
IDEA #3: Use
a multi-layer ring: additional strengthening rings, rings having different
hardness and elasticity, rings which have a gap in between them where
the gap is filled with an energy-absorbing material.
|
OPERATOR: Apply
inflatable constructions
To make
a product more effective or convenient or to reduce its weight,
consider applying pneumatic (inflatable) constructions instead
of mechanical ones.
|
IDEA #4: Replace
the ring with an airbag inflated by the impeller burst.
|
OPERATOR: Transform an object's shape
Replace
a mechanically weak element of an object with one having a special
shape.
Consider
utilizing the following shapes:
- ribs
or corrugated constructions, T-shapes, channels, or box constructions
(continued
. . . )
|
IDEA #5: Make
a thin ring that has reinforcing ribs. 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.
OPERATOR:
Transform an object's shape (continued)
- a shape
that conforms to expected wear
ILLUSTRATION:
Sloped heels
The backs
of shoe heels tend to wear down. In the past this was attributed
to incorrect walking habits.
Shoes
were designed with heels shaped as if they were already
worn down – that is, which sloped up in the back. Jogging
shoes and many other types of shoes and boots are now designed
this way.
The
result: the shoes are subjected to less wear.
(Continued
. . . )
|
IDEA #6: Determine
the places where the ring is most likely to break, and reinforce these
places.
OPERATOR:
Transform an object's shape (continued)
- opposite
to a subsequently-occurring, undesired change
ILLUSTRATION:
Increasing spring strength
To increase
the strength of a spring, the spring wire can be stretched
before it is coiled.
Use an opposite
shape. Another approach is to bend the spring wire before it
is coiled. The bend must be in the opposite direction to the
way the wire will bend when it is coiled.
The result: a preliminarily bent spring is stronger and
more elastic.
|
IDEA #7: Introduce
preliminary stress – for example, use additional rings which have been
pressure-fitted to create a force directed toward the inside the ring.
|
OPERATOR: Transform an object's structure
Consider
altering the structure or composition of an object in order
to strengthen the most heavily-loaded or weakest part(s).
For this
purpose:
- modify
a portion of a substance
ILLUSTRATION:
Texturing iron sheets
To strengthen
parts, in particular, space hardening to a rolled iron sheet,
by modifying this part, a heated metal plate is rolled
to produce a relief surface. The projections are then cooled
and the plate is rolled with smooth rollers to flatten it.
The
result: a flat plate can be produced which has a tempered
(hardened) texture in certain regions.
(Continued
. . . )
|
IDEA #8: Use
thermal treatment to harden the ring material.
|
OPERATOR: Transform an object's structure (continued)
- substitute
with a set of parts
ILLUSTRATION:
Using glass panes in a fighter
The original
bulletproof glass windows used on fighter aircraft had a serious
defect: When a bullet hit the window, a network of cracks
formed and obstructed the pilot’s vision.
Substitute
a large piece with a set of smaller parts. The glass can
be strengthened by forming the windows out of smaller panes
of glass cemented to an acrylic plastic sheet. Transparent adhesive
is used to join the edges of the glass panes.
The
result: when a bullet hits the glass, only the affected
pane cracks.
(Continued
. . . )
|
IDEA #9: Make
the ring out of separate layers so that cracks that develop on the inside
will not "spread."
|
OPERATOR: Transform an object's structure (continued)
- introduce
a strengthening additive
ILLUSTRATION:
Fibrous concrete
Ferro-concrete
often develops fractures under tension. The fractures easily
spread due to the dynamic effects of forces, vibrations, temperature
changes, etc. Reinforcement with metal bars is ineffective
because the bars are too sparsely distributed throughout the
concrete.
Concrete
can be reinforced by artificial fibers (steel, glass, basalt
or synthetics) that are evenly distributed throughout the concrete
as it is manufactured. Wires from used steel ropes are especially
convenient for this purpose.
The result: Fibrous concrete used in airport runways has
shown twice the service life of traditional ferro-concrete.
|
IDEA #10: Use
special threads, such as are found in bullet protection vests.
IDEA
#11: Use Ferro-concrete or some other composite material.
|
OPERATOR:
Introduce a strengthening elements
To
increase the mechanical strength of an object, try to use an
object or material that supplies strength for the required time
interval and can be easily removed afterwards.
ILLUSTRATION:
Transporting
window glass
While being
transported, sheets of window glass are separated by paper,
protected by chips, and packed in wooden cases. Even with these
precautions, however, the glass often breaks.
Use material
that supplies strength for the required time interval. Each
sheet can be covered with a thin film of oil, and the sheets
joined together to form a block. The glass can then be transported
as a solid block, which is much stronger than the individual
sheets.
The result:
tests show that when dropped from a height of two meters, the
glass block sustains little damage. Conversely, more than 50
percent of the glass packed in the usual way breaks.
|
See IDEA #3 (multi-layer
ring).
|
OPERATOR:
Pre-load an object
Consider
pre-loading an object in a way that will counter undesirable
stress. When the object is stressed, the pre-loading must be
overcome before undesirable stress develops. Inner stress can
be created in advance.
ILLUSTRATION:
Manufacturing
pre-stressed reinforcing rods
To make
pre-stressed, reinforced concrete, reinforcing rods can be pre-loaded.
For this purpose they are heated to 700 degrees C and clamped
in place. Concrete is then poured around the rods. Only rods
made of high-temperature steel can withstand the heat, but such
rods are too costly for most construction applications.
For less expensive
pre-stressed reinforcement, a steel bar can be connected to a
reinforcing rod. The bar is then heated to 700 degrees C.
The
result: as it heats, the bar expands, stretching and pre-stressing
the cold reinforcing rod.
ILLUSTRATION:
Strengthening
a gun barrel
Pre-loading
a gun prevents the barrel from rupturing when the gun is fired.
Two ways to do this are as follows:
1 -- a steel
ring or pipe is pre-heated and placed around the barrel so that
as it cools, it tightens and reinforces the barrel
2 -- stretched
wires or bands can be wound around the barrel.
The result
is a reinforcing effect against pressure in the barrel.
|
IDEA #12: Create
inner stresses inside the ring. This can be done, for example, using wiring,
banding, a double-ring structure, etc.
|
OPERATOR:
Duplicate critical elements
To increase
an object’s reliability, consider duplicating the most important
or most unreliable subsystems or components.
|
(Same as IDEA #3.)
|
OPERATOR:
Substitute for a set of simple (disposable) objects
Substitute
an expensive or complex object with a set of inexpensive or
simple objects, foregoing some desirable properties (e.g., longevity)
as a result. If possible, make the object disposable.
|
IDEA #13: Use
a disposable ring – i.e., a ring that will be destroyed while absorbing
the energy of the fragments.
|
OPERATOR:
Exclude auxiliary functions
Auxiliary
functions provide support and contribute to the execution of
the object's primary function(s).
In many
situations an auxiliary function can be excluded (along with
the elements and/or parts associated with the auxiliary function)
without deteriorating the performance of the primary function(s).
Consider
the following:
- Exclude
correcting functions
- Exclude
protective functions
- Exclude
housing functions
|
Consideration 1:
The ring
performs an auxiliary (i.e., corrective) function.
|
OPERATOR:
Exclude correcting functions
Consider
any function of your object whose sole purpose is to fix some
inherent shortcoming (harmful action) of the object. Identify
the shortcoming that is eliminated by each correcting function.
Can the cause of the shortcoming be eliminated? If so, the object
will no longer require this correcting function.
Sometimes
an object can operate satisfactorily without eliminating the
shortcoming. If so, the correcting function can also be eliminated.
|
Consideration
1 (continued): The inherent shortcoming that the containment ring
is designed to correct is an impeller burst. We should therefore consider
a new problem: improving the mechanical strength of the fan to prevent
it from bursting, and thus eliminating the need for a containment ring.
|
OPERATOR:
Exclude elements
Consider
excluding elements of an object by delegating their functions
to resources.
|
Consideration 2:
We should also consider how other system elements might be used to
perform the ring’s function.
|
OPERATOR:
Change the principle of operation
To simplify
an object or process, consider changing the basic operating
principle that is used.
In particular,
replace a mechanical field for another, more easily-controlled
field.
|
IDEA #14: Use
a magnetic field to contain the fragments.
|
OPERATOR:
Self-service
Make your
system (object) serve itself, including support and repair operations.
For this purpose:
Step 1:
identify the service functions performed for your object by
another object
Step 2:
consider object's elements to identify which of them can fulfill
these functions
|
Consideration 3:
The fan should protect itself. We should consider the new problem
formulated in Consideration 1.
Evaluating
results
The Evaluating
results section of the Improver software offers the following options:
Working with the typical
problems presented by the Improver yielded 13 ideas. These ideas were
evaluated and prioritized, taking in consideration the following criteria:
- Performance
- Feasibility
- Novelty
The results are as
follows:
Ideas #1 and 6: Vary
the thickness of the ring, reducing the thickness where permissible. Determine
the places where the ring is most likely to break, and reinforce these
places.
Idea #2: Reduce the
energy of the fragments by reducing their weight (i.e., "help"
the impeller break into smaller pieces). The ring is therefore not required
to be as strong, and can be made lighter as a result.
Ideas #3 and 9: Use
a multi-layer ring: additional strengthening rings, rings having different
hardness and elasticity, rings which have a gap in between them where
the gap is filled with an energy-absorbing material. Make the ring out
of separate layers so that cracks that develop on the inside will not
"spread."
Idea #5: Make a thin
ring that has reinforcing ribs. 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.
Ideas #7 and 12: Introduce
preliminary stress – for example, use additional rings which have been
pressure-fitted to create a force directed toward the inside the ring.
Create inner stresses inside the ring. This can be done, for example,
using wiring, banding, a double-ring structure, etc.
Idea #8: Use thermal
treatment to harden the ring material.
Ideas #10 and 11:
Use special threads, such as are found in bullet protection vests. Use
Ferro-concrete or some other composite material.
Idea #4: Replace the
ring with an airbag inflated by the impeller burst.
Idea #13: Use a disposable
ring – i.e., a ring that will be destroyed while absorbing the energy
of the fragments.
Idea #14 (which proposed
the use of a magnetic field to contain the fragments) was excluded from
the list due to the inability of a magnetic field to absorb the amount
of energy we are dealing with in this system. Besides, fan can be made
from a non-magnetic material.
Enhancing
a selected idea
We selected an idea
that was considered highly feasible (Idea #2) for enhancement.
The options for enhancement
are as follows:
After selecting Enhance
product function efficiency, the following recommendations were provided
by the software:
|
OPERATOR:
Use a more effective form of energy
To
enhance an object’s function (or a process operation), consider
replacing the energy that provides an existing function or operation
with a more effective form of energy.
ILLUSTRATION:
Cutting steel
pipes with a directed explosion
The methods
conventionally used to cut steel pipes are labor-intensive,
time-consuming, and inconvenient in extreme environments. (Some
of these methods employ the use of gas or a single-point cutting
tool.)
Use a more
effective energy instead of the mechanical energy of cutting
by using a directed explosion. To do this, a metal pipe filled
with an explosive material curved into a ring is installed where
the pipe is to be cut.
The result: a simultaneous cut around the diameter of the
pipe. Note: The cut can be specified at any angle with respect
to the pipe’s longitudinal axis.
|
IDEA #15: If
the impeller breaks, a direct explosion should take place at the exact
moment of the break. This would serve two purposes:
Solving
secondary problems
The options for solving
secondary problems are as follows:
We select Resolve
a contradiction.
Idea #8 has a substantial
drawback: hardening the ring can make it more brittle.
By using the Resolve
a contradiction template, we obtain the following contradiction:
The idea [harden
the ring] is acceptable because it provides [higher strength], and is
unacceptable because it does not avoid [making the ring more brittle].
The following Separation
Principles are considered:
|
OPERATOR: Separating contradictory requirements in space
Try
to separate contradictory (opposite) requirements in space.
For this purpose:
Step 1: partition
the object
Step 2: assign each contradictory function or condition to a different
part.
ILLUSTRATION:
Coating method
Metallic
surfaces are chemically coated as follows: the metallic product
is placed in a pool filled with a metal salt solution (e.g.
nickel, cobalt, etc.). During the reduction reaction, metal
from the solution precipitates onto the product surface. The
higher the temperature, the faster the process; however, the
solution decomposes at high temperatures, and up to 75% of the
chemicals are wasted, settling on the bottom and walls of the
pool. Adding stabilizers is not effective, and conducting the
process at a low temperature sharply decreases production.
Apply separation
in space. The solution should be hot where it is near the
part, but cold elsewhere. The part is heated to a high temperature
before it is immersed in the solution, and the process itself
is conducted at a low temperature. One way of heating the part
is by applying an electric current to it during the coating process.
|
IDEA
#16: Introduce hardened segments uniformly distributed along the internal
side of the ring made from a steel with higher plastic properties (see
the Illustration entitled "Containers for jettisoning loads"
earlier in this case study). This idea is compatible with Ideas #3 and
9 (multi-layer ring design).
Reformulating
the initial problem and obtaining new ideas
The purpose of improving
the containment ring (reducing weight, increasing mechanical strength)
is to enhance its corrective (i.e., protective) function of preventing
fragments from flying away and causing severe damage. Thus, our new problem
is: "Flying fragments."
We return to the Develop
Concepts menu:
We select from a new
group of Operators for the typical problem Eliminate a drawback:
The cause of flying
fragments is the impeller burst.
The effect produced
by flying fragments is the damage to the system.
The problem of preventing
the impeller burst is already on our list of considerations. We can add
to the list the problem: Reduce the damage caused by flying fragments.
Since for the purposes
of this case study we are not targeting an exhaustive set of possible
solutions, we will limit the analysis to eliminating the drawback itself
– that is, to stop the fragments from flying. By selecting the item Eliminate
the drawback, we obtain the following list of Operators:
|
OPERATOR: Isolate the
system from the source of harm
Consider
isolating the system from the source of harmful effect.
In particular, in case of fire or explosion.
ILLUSTRATION:
Using foam to
contain blast fragments
When an
old factory foundation was being demolished by explosion, there
was a danger that blast fragments might damage nearby machine
tools.
Isolate nearby objects from an explosion. The blast site
was surrounded with a plywood form filled with foam.
As a result,
the danger of damage due to blast fragments was completely eliminated.
|
IDEA
#17: Use foam or foam-like material to absorb energy. For this purpose
we would need a special type of foam such as metal foam. We can also consider
using other fillings that absorb energy.
|
OPERATOR: Counteract
an undesired action
Consider
eliminating a harmful effect by using another effect. For this
purpose, consider:
combining
with another harmful effect available in the system
opposing
an action that causes a harmful effect with another, similar
action
neutralizing
the harmful effect with a countering effect
opposing
an action that causes a harmful effect with another, similar
action
ILLUSTRATION:
Fighting fire
with fire
Oppose
a harmful action with a similar action. When a brush fire
is raging, a backfire is set. When the brush fire and the backfire
meet, the flames die out – everything that can burn has
already been consumed.
The result:
brush fires can be controlled and extinguished.
|
IDEA
#18: Consider the possibility of "firing back," that is,
explode the ring at the same instant the impeller bursts, so that the
explosion shock wave counteracts the flying fragments. This idea is similar
to Ideas #13 and 14.
|
OPERATOR: Change an
undesired action
Consider
changing the undesired effect in order to make conditions secure
for the system. In particular:
redirect
the harmful action away from the system
increase
the intensity of a harmful action to the point where the effect
is eliminated
weaken
the harmful effect by stretching out the time in which the
action takes place
if the
harmful effect takes place at a point, consider changing the
point contact to a line, surface, or volume contact
|
IDEA
#19: Determine which directions are the least dangerous and try to
redirect the flying fragments in one of these directions.
Final
list of concepts (listed in order of feasibility):
-
Ideas #1 and 6:
Vary the thickness of the ring tube, reducing the thickness where
permissible. Determine the places where the ring is most likely to
break, and reinforce these places.
-
Idea #2: Reduce
the energy of the fragments by reducing their weight (i.e., "help"
the impeller break into smaller pieces). The ring is therefore not
required to be as strong, and can be made lighter as a result.
-
Ideas #3, 9 and
16. Use a multi-layer ring: additional strengthening rings, rings
having different hardness and elasticity, rings which have a gap in
between them where the gap is filled with an energy-absorbing material.
Make the ring out of separate layers so that cracks that develop on
the inside will not "spread." Introduce hardened segments
uniformly distributed along the internal side of the ring made from
a steel with higher plastic properties.
-
Idea #5: Make
a thin ring that has reinforcing ribs. 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. In conjunction with Idea #2,
sharp ribs can also break the fragments into smaller pieces.
-
Ideas #7 and 12:
Introduce preliminary stress – for example, use additional rings which
have been pressure-fitted to create a force directed toward the inside
the ring. Create inner stresses inside the ring. This can be done,
for example, using wiring, banding, a double-ring structure, etc.
-
Idea #8: Use thermal
treatment to harden the ring material.
-
Ideas #10 and
11: Use special threads, such as are found in bullet protection vests.
Use a composite material.
-
Idea #4: Replace
the ring with an airbag inflated by the impeller burst.
-
Ideas #15 and
18: If the impeller breaks, a direct explosion should take place at
the exact moment of the break. This would serve two purposes: (1)
It will create a counteracting force that can keep the fragments in
place, and (2) It will break the fragments into smaller pieces.
-
Idea #17: Use
foam or foam-like material to absorb energy. For this purpose we would
need a special type of foam such as metal foam. We can also consider
using other fillings that absorb energy.
-
Idea #13: Use
a disposable ring – i.e., a ring that will be destroyed while absorbing
the energy of the fragments.
-
Idea #19: Determine
which directions are the least dangerous and try to redirect the flying
fragments in one of these directions.
Conclusion
The advantages of
utilizing the Improver software versus the Contradiction Table are as
follows:
-
More recommendations
(Operators) are offered for a given problem situation (44 for the
Improver versus 11 for the Contradiction Table).
-
More ideas were
obtained (19 versus 6).
-
More specific
and refined recommendations allowed us to come up with more developed
concepts.
-
The Improver software
offered methods for enhancing a solution and guided us in reformulating
the problem, which expanded the "solution space" relevant
to the containment ring problem.
NOTES
1.
The portion of the case study conducted using the Innovation WorkBench
(IWB) System can be found
here.
2.
Also see also "Comparative Analysis of Selected TRIZ Tools," TRIZ
in Progress (Ideation International, 1999).
3.
"Tools Overview and Structure," Ideation/TRIZ Methodology course material
(Ideation International, 1995).
4.
The ISQ and Problem Formulator are recently-developed Ideation TRIZ
analytical tools.
5.
A recent Ideation TRIZ tool that incorporates the 40 Innovation Principles,
Separation Principles, 76 Standard Solutions, selected Patterns/Lines
of Technological Evolution, and more into an integrated, netlike structure.
See details in Boris Zlotin and Alla Zusman, "An
Integrated Operational Knowledge Base," from TRIZ in Progress (Ideation
International, 1999).
6.
The relatively high number of solutions was the result of limited
initial information about the problem and system, especially with regard
to constraints on system changes. We therefore aimed at an exhaustive
set of potential ideas, which could later be screened.
7.
Obviously, the "conventional" method of reducing the weight of the
ring by reducing the amount of material used would sacrifice the ring's
mechanical strength.
8.
This tool (as well as the 76 Standard Solutions) is suitable for problems
stated in terms of functions -- e.g., a system contains a harmful function,
an insufficient useful function, or a useful function is absent. The presented
problem, however, does not include a functional description of the situation.
9.
The application of ARIZ to this problem will be considered in a separate
paper.
10.
There is no apparent Physical Contradiction in the problem statement.
11.
The Improver's main features are detailed on this web site [Click
here].
12.
More information about the IWB can be found on this web site [Click
here].
|
Printer-friendly version