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TRIZ METHODOLOGY AND ITS USE IN SYSTEMATIC ENGINEERING
DESIGN
Marco Aurélio de Carvalho
Centro Federal de Educação Tecnológica do Paraná – CEFET-PR
DAMEC - Departamento de Mecânica
NuPES - Núcleo de Pesquisa em Engenharia Simultânea
Av. Sete de Setembro, 3165
80230-901 – Curitiba, PR, Brasil
Nelson Back
Universidade Federal de Santa Catarina
Departamento de Engenharia Mecânica
Caixa Postal 476
88010-970 – Florianópolis, SC, Brasil
Abstract. Technical innovation and creative problem solving are necessary for long-term
business survival. Traditional methods for innovation and problem solving do not always
suffice. In this paper, the TRIZ methodology for creative problem solving is presented and
its possible use in systematic product planning and conceptual engineering design is
discussed. TRIZ stands for Theory of Inventive Problem Solving, in Russian. It was created
in the 1950s in ex-USSR and has been developed ever since, but it was unveiled to the West
only some years ago. TRIZ is a powerful methodology for solving though technical
problems. Initially, the basic concepts of TRIZ are introduced and its best known problem
solving method - the inventive principles method - is presented. Then, a discussion on
establishing a descriptive model of the product planning and conceptual engineering
design process using concepts derived from TRIZ is made. For better understanding,
illustrative examples are provided along the text.
Keywords: Engineering design, TRIZ, Design theory and methodology, Product planning,
Conceptual design.
1. INTRODUCTION
During the 1980's and 1990's, special attention was paid to the business function of
manufacturing. Most companies have nowadays a quality system, mainly to assure final
product or service conformance to specifications. Few companies have focused on
improving their product development, to provide better products faster than the
competitors. As competition becomes stronger, satisfying the customer is not enough
anymore, and business strategies must be directed to innovation. Innovation can only be
achieved by the concurrent actions of all business functions. This paper is related to
technical innovation. More specifically, a powerful approach to technical innovation and
creative problem solving known as TRIZ and its possible use within product planning and
conceptual engineering design are presented.
Initially, TRIZ background and structure are presented. The underlying concepts of
TRIZ - ideality, contradiction and resources - are discussed. Then, the most widely known
problem solving method of TRIZ - known as inventive principles method - is presented. An
example of this methods' application is described. Finally, a report of research underway is
made. The research focuses on a descriptive model of the product planning and conceptual
engineering design process using concepts derived from the systematic approach of Pahl &
Beitz (1988), TRIZ and other methods.
2. BACKGROUND AND STRUCTURE OF TRIZ
Development of TRIZ started in the 1940s with works of Altshuller, in ex-USSR.
Altshuller (1984a, 1984b, 1996) had the main objective of finding alternatives to traditional
creative problem solving methods, that were based on trial and error. Altshuller approached
technical creativity by its main evidences: patents. He tried to figure out the underlying
process by which good solutions were found, no matter what type of technology was used.
By doing so he found regularities, that constituted the foundation of a knowledge base and
various methods for solving technical problems. Later, these methods were developed into
what Altshuller named TRIZ – Theory of Inventive Problem Solving.
Modern TRIZ is a wealth of methods for finding and solving problems, a knowledge
base, trends and laws. Main TRIZ researchers argue that the field is still in its infancy.
TRIZ still has methodology status and has yet to be further developed to achieve theory,
and possibly science status (Savransky, 1998b). The TRIZ methodology is relatively new to
western countries, but interest in it is growing fast. For better understanding of the whole
methodology, the complete structure of TRIZ is shown in Figure 1. The scope of this paper
is limited to the items painted in grey. These items are the basic TRIZ concepts and one
problem solving method. TRIZ problem solving methods are also known as contradiction
removing methods.
3. MAIN CONCEPTS OF TRIZ
The underlying concepts of TRIZ methodology are ideality (and the trends and laws
of technical systems evolution), contradiction and resources. These concepts are described
below.
3.1. IDEALITY AND TECHNICAL SYSTEM EVOLUTION TRENDS AND LAWS
The s-curve is the pattern of investment for a product, process or technology's
improvement versus obtained results (Foster, 1988). The curve is divided in four parts, or
evolution phases (shown in Figure 1). These are:
a) new product, process or technology creation;
b) adoption by a small amount of users (product or process) or strong developments
(technology);
c) market saturation (product or process) or small developments (technology);
d) substitution by a more advanced product, process or technology.
Figure 1 - The s-curve
Study of numerous products, processes and technologies has proven the pattern
shown above But how does a product, process or technology itself evolves? Is the evolution
unlimited? From his extensive patent research, Altshuller (1984a, 1984b) concluded that
the evolution of products, processes and technologies - that he generically named technical
systems - follows certain trends and laws. These are presented on Table 1. Technical
systems evolve according to these trends and laws, and towards the ideal technical system
(ITS). The ITS is a (non-) system that performs all necessary system functions. It is not and
will never be a real system. Nevertheless, it is useful for establishing the direction for
evolution of a real technical system.
The laws of creation are related to the S-curve phase a. According to the first law,
there are some typical subsystems that every technical system should contain. These typical
subsystems are engine, transmission, working system, control system and structure. The
law of energy conduction capability means that, for a system's function to be achieved,
energy should flow through its typical subsystems. The rythm synchronization law states
that subsystems should have compatible working frequencies.
Development of technical systems (phases b and c of the s-curve) follows the laws of
movement. The law of unlimited technical development means that a technical system can
always be technically improved (even when such improvement is small and does result in
sound effectiveness increase). According to the law of unequal subsystem development,
subsystems are non-uniformly developed i.e., some subsystems underperform or
overperform when compared to others in the same system. Overall system effectiveness can
be achieved by developing underperforming subsystems. The law of transition to the
supersystem states that, when increased effectiveness can not be achieved by the current
technical system (or even before), it will be transformed into a subsystem of another, higher
leveled technical system.
a) Creation b) Development c) Saturation d) Substitution
Investment
Return
Current
product,
process or
technology
Future
product,
process or
technology
Figure 1 - Structure of TRIZ Methodology
The trends are related to the end of a technical systems' life (phases c and d of the s-
curve). The trend of simplification states that sucessive generations of the same technical
system evolve to complicated and then from complicated to simple, by integration. The
trend of transition to subsystem means that increased effectiveness of a technical system is
reached when it evolves from macrosystem to microsystem. Effectiveness is also increased
by increasing system automation. According to the trend of increasing use of substance-
fields, systems become more dynamic, more controlable, more durable and more effective
when solid and stiff subsystems are replaced by interactions of substances and energy or
information carriers.
Table 1 - Trends and laws of the evolution of technical systems
Group Trends and laws
Law of completeness
Law of energy conduction capability
Laws of creation
Law of rythm synchronization
Law of unlimited technical development
Law of unequal subsystem development
Laws of movement
Law of transition to supersystem
Trend of simplification
Trend of increasing number of functions
Trend of transition to subsystem
Trend of increasing automation
Trends
Trend of increasing use of fields
Particles
method
Preliminary
analysis
methods
Technical
system
evolution
laws
Algorithm for
inventive
problem
solving
Contradiction
analysis
Personal
creativity
development
FCA -
Function -
component
analysis
Databases:
effects,
standard Su-
fields etc.
Reengineering
or mini-
problems
TRIZ
Analysis of
constraints Substance-
field (Su-
field) analysis
Inventive
principles,
contradiction
matrix
Evolution
prediction
analysis
Innovation or
maxi-
problems
Interaction
analysis
Problem
solving
Separation
method
- Ideality
- Contradiction
- Resources
Problem
solving
methods
3.2. CONTRADICTION
Contradictions can be defined as conflicting requirements on the same technical
system. Considering an ordinary welding iron: the tip should be positioned far from the
handle for not hurting operator's hands and should be close to the handle for better welding
precision. Thus, the element that connects the handle to the tip should be long and should
be short.
There are three possible approaches to solving a contradiction (Savransky, 1998):
extremist, trade-off and creative. The extremist solutions to the welding iron problem are
making the connecting element long or short. A long element would avoid hurting, and
control would be difficult. A short element would make the iron easy to control, but
operator's hands would be hurt. The trade-off solution would be making the connecting
element not too short and not too long. A compromise is established between opposing
requirements. The creative approach to the same problem means trying to comply to both
opposing requirements. An example of creative solution would be giving the connecting
element a horseshoe's form. By doing that, the operator's hand would be close to the tip for
better control and would not be hurt, because the connecting element is long.
3.3. RESOURCES
Resources are elements of the system or its surroundings that are not being used but
could be used to improve effectiveness. Types of resources include: internal, external,
natural, system, functional, space, time, field (energy), substance, information etc. An
example of using an available field resource was the invention of the turbocompressor to
obtain overpressure of air in an internal combustion engine. The turbocompressor
transforms a part of the energy of exhaust gases in intake air overpressure, making it
unnecessary to use engine's mechanical power to compress intake air.
Using the laws of technical system evolution, solving system contradictions and using
resources bring a technical system closer to the ITS.
4. PROBLEM SOLVING WITH TRIZ - THE INVENTIVE PRINCIPLES
METHOD
From the point of view of mechanical systems design, problem solving can be
considered TRIZ main part. Problem solving with TRIZ starts with a preliminary analysis.
The objective of this analysis is to correctly formulate problems, define the ideal final
result, verify the system according to the laws of evolution, find available resources, and
find the contradictions to be solved. Only after the preliminary analysis should the problem-
solving methods be used.
Contradiction analysis is a method for finding contradictions in a technical system.
First, all system requirements should be listed. Then, pairs of requirements are
comparatively analysed for contradictions. This process is very similar to - and could be
even replaced by - the one of completing the roof in a house of quality.
After contradictions have been identified, a method for solving contradictions should
be used. The method presented in this paper is the method of inventive principles.
The inventive principles method is one of the easiest and most popular TRIZ method.
It is based on two main concepts: engineering parameters and inventive principles.
Engineering parameters are variables common to technical systems from different
disciplines. The 39 engineering parameters are presented on Table 2.
Table 2 – Engineering parameters
1. Weight of moving object 11. Tension, pressure 21. Power 31. Harmful side effects
2. Weigh of binding object 12. Shape 22. Waste of energy 32. Manufacturability
3. Lenght of moving object 13. Stability 23. Waste of substance 33. Convenience of use
4. Lenght of binding object 14. Strenght 24. Loss of information 34. Repairability
5. Area of moving object 15. Durability of moving
object 25. Waste of time 35. Adaptability
6. Area of binding object 16. Durability of binding
object 26. Amount of substance 36. Complexity of object
7. Volume of moving
object 17. Temperature 27. Reliability 37. Complexity of control
8. Volume of binding
object 18. Brightness 28. Accuracy of
measurement 38. Level of automation
9. Speed 19. Energy spent by moving
object 29. Accuracy of
manufacturing 39. Productivity
10. Force 20. Energy spent by binding
object 30. Harmful factors acting
on object
The inventive principles are the result of generalization and grouping of solutions
found in patents. These principles were repeatedly used in solving problems from different
disciplines. The 40 inventive principles are shown in Table 3. For example, principle #35 –
parameters and properties change could mean changing physical aggregate state,
concentration, density, consistency, flexibility, temperature etc. Principle #10 could mean
performing actions before needed, pre-arranging objects before they act etc. A detailed
explanation of each inventive principle can be found in Altshuller (1996).
The contradiction matrix (presented in the Appendix) is a tool for selecting the
inventive principle to be used to resolve a particular contradiction. In the matrix rows,
engineering parameters that should be improved are listed. In the matrix’ columns are the
engineering parameters that can be degraded as a result of improving the parameter in the
row. The numbers at the intersecting cells correspond to the inventive principles that most
probably point to the contradiction resolution. The inventive principles can also be used
without the matrix. In this case, the problem solver looks at the list and tries to derive from
it useful ideas to solve his/her problem.
The problem described below is simple and could be solved with other methods, but
it will be used to illustrate problem solving with the inventive principles method.
The bracket shown in Figure 2 is used in the transmission of a fun kart under
development at CEFET-PR. This part is supported by the rear axle, which passes through
the inferior hole. The superior hole supports an intermediary axle. The bracket must rotate
around point A (rear axle center line). At present, the distance between superior and inferior
holes (distance C) is unchangeable. It is necessary to make distance C changeable. In fact, it
must be easy to adjust distance C and, once it is adjusted, to keep the adjustment.
Table 3 – Inventive principles
1. Segmentation 11. Beforehand cushioning 21. Skipping 31. Porous materials and
membranes
2. Taking out 12. Equipotentiality 22. Converting harm into
benefit 32. Color changes
3. Local quality 13. Reverse 23. Feedback 33. Homogeneity
4. Asymmetry 14. Spheroidality 24. Intermediary principle 34. Discarding and
recovering
5. Merging 15. Dynamism 25. Self-service 35. Parameters and
properties change
6. Universality 16. Parcial or excessive
action 26. Copying 36. Phase transitions
7. Nested doll 17. Another dimension 27. Cheap short-living
objects 37. Thermal expansion
8. Anti-weight 18. Mechanical vibration 28. Substitution of
mechanics 38. Strong oxidants
9. Preliminary anti-action 19. Periodic action 29. Pneumatics or
hydraulics 39. Inert atmosphere
10. Preliminary action 20. Continuity of useful
action 30. Flexible shells and thin
films 40. Composite materials
Figure 2 - Fun kart transmission bracket
The ideal transmission bracket is no bracket at all. The closest to ideal bracket is one
that adjusts itself to the required distance C and keeps itself adjusted.
Available resources include available clearances, surrounding components that could
be modified to carry out bracket functions, unused material properties, material that does
not carry load with present geometry, available energy (vibration, rotation), gravity,
movement of surrounding components etc.
The contradiction is: the bracket has to be dynamic for adjustment and has to be static
for keeping the clearance. This contradiction has to be translated into engineering
parameters. The chosen parameters are #35 (adaptability) and #12 (shape). The intersection
of line #35 and column #12 of the contradiction matrix results in principles #15
(dynamism), #37 (thermal expansion), #1 (segmentation) and #8 (anti-weight). These
principles should be used for deriving conceptual solutions to the problem. Several
C
A
concepts were generated and two of the most promising are shown in Figure 3.
In the solution at left, the bracket is separated in two parts (1 and 2). These parts are
connected by a grooved pin (5) that is kept in position by a nut (3), a washer (4) and an
elastic ring (6). Adjustment is done by removing the nut and washer, partially removing the
grooved pin, repositioning and fastening the parts.
The solution at right involves a double-threaded screw (3), two nuts (2) and two
connecting elements (1 and 4). Both solutions are based on inventive principles #15 and #1.
Figure 2 - Two solutions to the fun kart transmission bracket problem
5. USE OF TRIZ IN MECHANICAL SYSTEMS DESIGN
The systematic approach to engineering design proposed by Pahl & Beitz (1988) is a
well proven methodology, valid for component design as well as complex systems design.
TRIZ includes some very useful elements that are not included in the traditional systematic
approach to mechanical systems design. Altough TRIZ is based on knowledge from all
technical areas, its scope is narrow, directed to specific problems. How could TRIZ be
effectively used in systematic design?
According to León-Rovira & Aguayo (1998), TRIZ concepts of ideality,
contradiction and resources should be used along the whole design process. TRIZ problem
solving methods can be used for removing contradictions every time these are found.
Terninko (1998) and Domb (1998) suggest combining TRIZ, QFD and Robust
Design. QFD should be used to identify conflicts between requirements (house of quality
roof), that could be resolved with TRIZ. Robust design should be used to find optimum
levels of technical parameters.
Savransky (1998b) suggests using TRIZ methods in the upfront of the development
process, for obtaining innovative concepts. Traditional engineering methods should then be
used for further concept development. According to Savransky (1998b), the same
procedure could be used to redesign products.
Malmquist et al. (1996) suggest unifying TRIZ and the systematic approach. The
systematic approach should be used as a framework with TRIZ elements included in some
points. Linde & Hill (1993) have proposed WOIS - Widerspruchsorientierte Innovations-
strategie or Contradiction-Oriented Innovation Strategy. This is a methodology for
complex product development, based on German systematic design methodologies and
1
3
4
5
2
6
3
2
4
1
TRIZ. In their book, Linde & Hill present many case studies, proving that their approach
works properly.
The authors are presently working on a descriptive model of systematic product
planning and conceptual design based on the systematic approach by Pahl & Beitz (1988),
TRIZ, and other creative problem solving methods. There are two central ideas to be
implemented in this model:
• to enhance reuse of design knowledge available in catalogs of conceptual
solutions, patent funds, and other sources;
• when development of solutions is needed, to prompt the engineering design team
to use the most appropriate method for each type of problem. Use of effective but
difficult problem solving methods like those of TRIZ is proposed only after trying
to solve problems with simpler methods like brainstorming (Osborn, 1953).
6. CONCLUSIONS
In this paper, the TRIZ approach to technical innovation and creative problem solving
was presented. Background, structure, main underlying concepts, and a problem solving
method – the inventive principles method – were described. Finally, possible use of TRIZ
within product planning and conceptual engineering design was analysed.
TRIZ is a powerful methodology for creative problem solving and innovation. It is
however complex, knowledge intensive, and focused on specific problems. Its integration
with systematic engineering design would result in a stronger methodology. The integration
should occur according to following guidelines:
• systematic engineeering design should be used as a framework, because it has a
broader scope;
• reuse of available design knowledge should be enhanced and problem solving
should be used only when necessary;
• the methodology should be progressive, i.e. use of complex problem solving
methods like those of TRIZ should be avoided when not necessary.
REFERENCES
Altshuller, G. S., 1998, 40 Principles: TRIZ Keys to Technical Innovation, Technical
Innovation Center, Worcester.
Altshuller, G. S., 1984a, Creativity as An Exact Science: The Theory of The Solution of
Inventive Problems, Gordon & Breach, Luxemburg.
Altshuller, G. S., 1984b, Erfinden: Wege zur Lösung technischer Probleme, Verlag
Technik, Berlin.
Domb, E., 1998, QFD and TIPS/TRIZ, TRIZ Journal, http://www.triz-journal.com.
Linde, H. & Hill, B., 1993, Erfolgreiche Erfinden: Widerspruchsorientierte Innovations-
strategie für Entwickler und Konstrukteure, Hoppenstedt, Darmstadt.
Osborn, A. F., 1953, Applied Imagination, Charles Scribner’s Sons, New York.
Savransky, S. D., 1998a, TRIZ, The Triz Experts, Fremont.
Savrasnky, S. D., 1998b, Personal Communications.
Terninko, J., 1998, The QFD, TRIZ and Taguchi Connection: Customer-Driven Robust
Innovation, TRIZ Journal, http://www.triz-journal.com.
APPENDIX - CONTRADICTION MATRIX
