Containment ring problem - Part 3

A comparative case study using the Contradiction Table, Ideation Improverä, the Innovation WorkBenchä System software1 and IMC TechOptimizerä 3.0

© 2000 Ideation International Inc
azusman@ideationtriz.com

 

Part 3

Introduction

Presented here is the final portion of the comparative case study, including the protocol generated as a result of working on the problem utilizing the Invention Machine Company’s TechOptimizer, version 3.0. This work was carried out by Peter Ulan2, concluding a substantial undertaking to create the first comprehensive comparative study of the efficiency of various TRIZ tools.

Summary

The final results of the comparative study are presented in the List of ideas (Appendix 1) and the following table 1.

Category

Tool utilized
 

Contradiction Table

Improver

IWB

Tech Optimizer

Number of Directions (or problem statements) offered

3

6

18

7

Number of relevant recom­mendations (or Operators) offered

11

44

>100

>25

Number of ideas obtained

6

19

34

11

Distribution of “the best ten” ideas

1

9

10

4

Recommendation/idea ratio

1.83

2.32

2.94

2.27

Time spent

2-4 hours3

1.5 days

2-3 days4

One day

Conclusions

An analysis of the results supports the following conclusions:

  1. The IWB provided the highest number of Directions (Table 1, Category A), recommendations (B) and solution ideas (C) - in other words, it is the most exhaustive tool.
  2. The Containment ring problem (weight versus mechanical strength) can be considered as a rather typical problem, that is, frequently faced in various industries. Given the results (“the best ten” ideas distribution (Table 1, Category D), time spent for obtaining solutions (F) and price of the tools, it is obvious that for a problem of that type, the Improver is the most cost /time /effective tool.
  3. All obtained ideas can be divided into groups according to the system (subsystem) they recommend to change. The table 2 (below) shows how these ideas are distributed between tools utilized:

System/ subsystem

Number of ideas per group

Number of ideas per tool
   

CT

Impro- ver

IWB

TO

Modifying the ring

18

5

14

18

6

Changes to fragments/blade/fan

11

0

3

11

4

Changes to testing procedure

35

0

0

3

1

Ring replacement

2

1

2

1

0

The distribution above illustrates the fact that the largest amount of ideas is related to the containment ring improvement (in accordance with the original problem statement). At the same time, the IWB is also more effective when the possibilities to enhance an existing system are rather exhausted and a new approach to a long-standing problem is necessary (11 ideas versus 1-5 for the other tools for the group #2).

  1. The IWB (and, to a lesser extent, the Improver) is redundant - i.e., the idea/recommendation ratio for the IWB (Table 1, Category E) was 2.94 versus 2.27 for the TechOptimizer. This redundancy can be characterized by the following positive and negative features:

Positive
  1. Provides with the opportunity to nearly exhaust potential solution space, which is an important advantage in situations when it is critical to be sure that the best possible solutions are obtained (to secure intellectual property through obtaining patents, for example).
  2. When working with the IWB, different recommendations often lead to similar ideas. For this reason the user avoids missing good ideas that did not, at first, attract his attention. (This feature is especially important for new users who have little or no experience in TRIZ and TRIZSoft).
  3. New or inexperienced users often merely ‘browse’ through the software without paying adequate attention to the recommendations presented. A similar recommendation appearing again and again tends to result in (1) the user becoming more inclined to give it credence, and (2) the user gradually developing a solution (making a transition from feeling “There is nothing here “ to - Wait, there is something here” and finally - “Wow, this is great!”).
  4. Due to this redundant/recurrent structure, the user never finds himself in a situation of having explored every pathway to no avail, or having no idea how to continue with his problem-solving efforts. Additional pathways to explore are always presented (though after a while the number of new ideas generated will necessarily drop).

Negative
  1. Exhausting all possible solution pathways takes time. For a problem similar in scope to the Containment Ring problem, carrying out this work using the IWB should take approximately 2-3 days, whereas it took about a day using the TechOptimizer. (The Improver takes about 1.5 days.)
  2. A new user may get a feeling that he/she is ‘going in circles.’ To optimize the results/time/exhaustiveness issue, the IWB was designed in accordance with the 80-20% rule (i.e., 20% of the total effort put forth should produce 80% of the results). If exhaustiveness is not mandatory, the time required can be significantly reduced, while promising ideas will surface during the first hours of work.
  1. Notwithstanding our efforts to create an unbiased comparative case study, we cannot completely exclude the influence of such factors as TRIZ expertise, adeptness or previous time spent in using the tools, etc. We invite others to conduct their own comparison using this or a similar case study, and gladly welcome the resulting data, recommendations, and critiques.

 

Ideation International
Detroit
October 2000

Appendix 1

List of ideas

(In the order of preference)

Idea Description

Tool utilized
 

CT

Improver

IWB

TO

Internal ribs with sharp edges can counteract flying fragments breaking them into smaller pieces

    

#146

  

Make a thin ring, which 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

  

#5

#11

  

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 energy-absorbing material

#6

#3, #16

#15

#3.4

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

    

#33

  

Make the ring out of separate layers so cracks, which develop inside, won’t spread

  

#9

#16

  

Explode the ring in the moment of the impeller burst. Use the explosion wave to create a counteracting force

  

#15 #18

#20

  

Use of special threads, such as in bullet protection vests

  

#10

#9

  

Introduce strong fibers in the impeller blades that are capable to hold fragments after blades crash

    

#25

#4.4

Reduce the mass of the fragments to reduce damage

  

#2

#5

#4.1

Reduce the energy of fragments by reducing their weight (i.e. help the impeller break into smaller pieces). That will allow the ring to be made less strong and thus lighter

    

#5a

  

Generate mechanical stress. For example, use additional rings which have been pressure-fitted to create a force directed toward the inside the ring

  

#7

#7

#4.2

Create inner stresses inside the ring: This can be done, for example, using wiring, banding, double ring structure, etc.

  

#12

#18

#4.3, #4.7

Make the ring as an assembly made of light-weight parts that are easy to move for testing purposes.

    

# 1

#3.2

Provide high airflow with low rotational speed of the fan. Perhaps utilize several slow fans instead of one that rotates quickly

    

#2

  

Utilize a "weak" ring that will absorb energy as it is destroyed

#2

  

#3

  

Perform testing without removing the ring

    

#4

  

Vary the thickness of the ring tube. Reduce the thickness where permissible

#3

#1

#6

  

Use treatment to harden the ring material

  

#8

#8

  

Replace the ring with the airbag inflated by the impeller burst

  

#4

#10

  

Make the ring corrugated in two planes

    

#12

#4.6

Find where the rings usually break and reinforce these places

  

#6

#13

  

Use metal concrete or other composite materials

#3

#11

#17

  

Change the ring thickness or strength or other containing capabilities at the moment of impeller burst

    

#19

  

Disintegrate the fragments

    

#21

#4.5

Utilize special geometrical shapes to create traps for the fragments. For example, make the ring in the form of spring

    

#22

  

Create a combination of pressurized air and liquid to counteract fragments

    

#23

#4.8

Create a safe pathway for fragments

    

#24

  

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)

  

#17

#26

#4.9

Define less dangerous directions and redirect fragments to these directions

  

#19

#27

  

Distributing the harmful energy between more fragments (see also ideas # 7 and 21: reducing energy /mass of fragments)

    

#28

  

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

    

#29

  

Disposable ring - consider that the ring will be destroyed while absorbing all the energy of the fragments (similar to idea # 3)

#2

#13

#30

  

Consider various types of support while transporting the ring

    

#31

  

Learn in detail the process of transportation and look for the ways to reduce the number of liftings of the ring

    

#32

  

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

    

#34

  

Use magnetic field to contain fragments

#1

#14

Group 7

  

Consider using additional protection from flying fragments should the reliability of the ring be insufficient7

#5

      

Total number of solutions

6

19

34

11

 

Endnotes:

  1. The portions of the case study conducted using the Contradiction Table, Improver, and Innovation WorkBench (IWB) System have been published in previous issues.
  2. An experienced TRIZ specialist who has used the TechOptimizer for many years in his professional work.
  3. It may take a day to explore all 40 Principles (without use of Contradiction Table for Principles selection)
  4. The containment ring problem has long been used as an Ideation case study; the time given is an estimate.
  5. Amount of ideas related to testing procedure is low because of limited information on the subject.
  6. Here and forth the symbol # indicates the number originally assigned to an idea (see parts 1 and 2).
  7. Apparent idea