TRIZ: A Systematic Approach to Innovative Design    

© Valeri Souchkov, 1996, revised 1999. 

Introduction  

Engineering design involves the whole range of different theories and methods. Most of them aim at a mapping of given requirements and demands onto a description of physically realizable design product. However, formal design theories are only available at later design phases which are performed after a feasible design concept has been proposed and verified. Due to this, the early design phases lack sufficient computer aid and innovative design is still regarded as an art instead of science. 

Originated by Russian engineer Genrikh Altshuller, the Theory of Inventive Problem Solving (abbreviated as TRIZ) is a collection of domain-independent techniques for innovative engineering design. The TRIZ techniques have proven successful during the long-term use in various industries. Each technique consists of a number of guidelines, rules or principles which indicate how to cope with a specific problem or situation. Unlike the well known techniques for psychological activation, for instance, brainstorming, TRIZ provides a systematic methodology for innovative engineering design.  

This article discusses  TRIZ background and philosophy and makes a brief overview of several TRIZ techniques. 

TRIZ Background and philosophy  

TRIZ was originated by Russian scientist and engineer Genrikh Altshuller. In the early 50^th, he started massive studies of patent collections. He targeted at revealing similarities and common patterns between design problems and solutions which resulted in patents. More than ten years of research resulted in understanding of origins of inventive problems and formulation of general principles of inventive design.  

Later, many researchers and practitioners of the former USSR united efforts and largely extended Altshuller’s approach. It is estimated that by the end of 1984, more than 300 research and educational TRIZ centers were founded in the former USSR.  

TRIZ philosophy is based on the fact that evolution of technology is a regular process. The evolution of artificial systems undeniably correlates with the evolution of customer needs and social trends, and this is the bi-directional process. Apart from that, evolution of every area of engineering influences evolution of other areas.   

Another major discovery was revealing the origins of inventive problem: contradictions. A contradiction arises when two mutually exclusive design requirements are put on the same object or a system. For example, the walls of a space shuttle have to be lightweight to decrease the mass of the shuttle when bringing it to the orbit. However, this cannot be done by simply decreasing the thickness of the walls due to thermal impact when entering the Earth atmosphere. A contradiction results in the two conflicting design parameters: the walls have to be heavy and lightweight at the same time.  

When a designer faces a contradiction that cannot be solved by redesigning a technical system in a known way, this means that he faces the inventive problem, and its solution principle resides outside a domain the technical system belongs to.  

There are two ways to solve problems that contain contradictions: by finding a compromise between two potentially conflicting requirements (optimization) and by eliminating the contradiction. TRIZ is aimed at solving problems by resolving contradictions.  

More than 40 years of studying patents in different areas of engineering resulted in several important discoveries which form the TRIZ philosophy:  

• Every design product evolves according to regularities, which are general for every engineering domain. These regularities can be studied and used for innovative and inventive problem solving, as well as for forecasting the further evolution of any design product in design terms.
• Design products, like social systems, evolve through the elimination of various types of contradictions. The principles for eliminating the contradictions are common for all areas of technology.
• An inventive problem can be represented as a contradiction between new requirements to a design product, which is no longer capable of meeting the requirements. Finding an inventive solution to the problem means elimination of the contradiction under the condition that no compromise is allowed.
• There is a universal criteria of the best possible solution: ideality. The degree of ideality means the ratio between useful effects produced by a design product and  material, energy and information expenses necessary to produce the useful effects.
• Frequently, when searching for inventive solution to a problem formulated as a contradiction, there is the need to use physical knowledge unknown to the domain engineer. To organize and guide the search for appropriate physical knowledge, pointers to physical effects should be used. In the pointers, the physical phenomena are identified with the lists of technical functions, which can be achieved on the basis of the phenomena.

In contrast to well known methods for mental activation or traditional design methods which aim at finding a specific solution to a specific problem, such as brainstorm, TRIZ organizes translation of the specific problem into abstract problem and then proposes to use a generic design guideline or a pattern which is relevant to the type of the problem (figure 1). As clear, by reasoning at the level of abstract (conceptual) models, the search space can be significantly reduced that makes it easier to find the needed solution concept quickly.  
  

Modern TRIZ includes the following parts:  

• Laws and trends of the technology evolution. This part of TRIZ studies and formulates general trends of engineering system evolution.
• Problem solving techniques. The techniques aim at building a problem model and producing recommendations on how to solve the problem. Among them are:

• Principles for the elimination of technical contradictions;
• Inventive standards which solve inventive problems by representing them in terms of substance-field interactions and applying generic patterns for interaction transformations.
• Pointers to effects. This part of TRIZ focuses on studying how to use the knowledge of natural sciences (physics, chemistry, geometry) in the inventive process.
• Algorithm of Inventive Problem Solving, an integrated technique aimed at solving most difficult inventive problems that contain physical contradictions.

• Collections of selected patents. This part contains patent descriptions drawn from diverse engineering domains. The patents are structured according to inventive principles used to eliminate one or another type of contradictions. The patents can be used as analogous design cases illustrating the applicability of selected principles to make the problem solving process easier.
• Function Analysis is a modified version of traditional Value Engineering Analysis with the focus on functional decomposition and analysis of design products and technologies.
• Ideal Modeling (Function-based Redesign, also known as "trimming") aims at increasing ideality of design products and formulating new problems.
• Methods for mental inertia elimination are used to improve personal creative skills and avoid psychological inertia during problem solving.

TRIZ provides a systematic support for the following phases of conceptual design:  

• Analysis of ill-defined design problems by describing functions between the system components and identification of core problems by formulating contradictions.
• Generation of new solution concepts by using TRIZ problem solving techniques: inventive principles, inventive standards and pointers to physical effects.
• Producing technological forecast of a selected design product using TRIZ technology evolution trends.

   

The Laws of the Technology Evolution.  

The importance of the laws of evolution is that they can be used to estimate what phases of evolution a design product passed and what phases the product is going to pass. As a consequence, it is possible to predict what changes the design product will experience in future and to develop a strategic plan for new product development. 

The most important trend of the technology evolution is the trend of the ideality growth. It states that during evolution over the time, any technical system tends to increase a ratio between the overall degree of performance of the system and expenses needed to provide the required degree of performance. The trend indicates a principal design requirement which every designer has to keep in mind while designing new products: a system being designed must be able to deliver every desired function with the highest degree of performance whereas the expenses required to provide the product's life-cycle should be as less as possible. The expenses in this definition are all types of energy, material and information resources required to deliver the given functionality and meet all other requirements.  

Apart from the trend of the ideality growth, there are eight other laws in TRIZ:  

• Law of system completeness: a technical system tends to complete its material-energy structure to deliver the required function.
• Law of energy bypass: a necessary condition of functioning of a system is to provide effective energy flows through all parts of the system. Accordingly the trend of ideality growth, systems tend to minimize amount of types of energy used as well as to minimize a number of energy transformations within a system.
• Law of irregularity of system's parts evolution: the more complex a system becomes during the evolution the more irregularly its parts evolve. As a result, further development of the system becomes more difficult due to contradictions arising between system's parts.
• Law of increasing a number of material-energy interactions: a system tends to increase the degree of interacting material-energy components to provide a higher degree of performance and controllability.
• Law of frequency and form adjustment. During evolution, a system tends to adjust frequencies and forms of interacting components.
• Law of dynamics growth. A system tends to replace existing designs of its movable parts or working tools with structures which have a higher degree of freedom.
• Law of transition to microlevel. A system tends to replace a physical principle behind its component delivering a main function with a new physical principle which utilizes properties of more fragmented materials, particles or physical fields.
• Law of transition to macrolevel. A system which has approached its limits of evolution can further evolve through merging with other systems (that produces a new function); or it can be eliminated if its function might be delivered by other systems.

Inventive Principles.  

A collection of inventive principles is the most known and widely used TRIZ problem solving technique. Each principle in the collection is a design guideline, which recommends a certain method for solving a particular inventive problem. There are 40 inventive principles in the collection, which are available in a systematic way according to a type of a contradiction that makes the problem non-solvable by the procedure of routine design. Examples of the inventive principles are:  

• Variability Principle: Characteristics of the object (or external environment) should change such as to be optimal at each stage of operation; the object is to be divided into parts capable of movement relative to each other; if the object as a whole is immobile, to make it mobile or movable.
• Segmentation Principle: To divide the object into independent parts; to make the object such that it could be easily taken apart; to increase the degree of the object's fragmentation (segmentation)

Another TRIZ problem solving technique is a collection of so-called inventive standards. While inventive principles operate with generalized technical parameters, inventive standards are more formal and context-dependent since they operate with a specific model of a design product. This makes the inventive standards more accurate than the inventive principles.  

While the inventive principles have to be used when a designer faces a contradiction, the inventive standards are used in those situations when a problem involves so-called undesired interaction between two or more system's components. There are several types of the undesired interactions:  

• missing: some parameter of a component has to be changed during operation, but we do not know how to change it.
• harmful: interaction between two component produces harmful effect.
• excessive: an action of one component on another is too strong.
• insufficient: an action of one component on another is too weak.
• coupled useful and harmful: interaction between two components is necessary to provide a useful effect, yet it causes a negative effect.

In technical terms, a physical field is a carrier of a particular function which is delivered by one of the components. Examples of physical fields are mechanical, acoustic, thermal, electrical, magnetic and electromagnetic.  

A basic substance-field model (SFM) consists of two substance components and a field between them (Fig. 4). For instance, SFM of a cup of coffee can be modeled as two substance objects: coffee (fluid) and the cup. Both the components interact with each other via mechanical field.  

In real systems, there are might be many types of fields involved into the same interaction. Since SFM is aimed at problem solving, it is always recommended to limit ourselves to a single field that is a cause of a problem. As seen, every technical system can be modeled in this way.  

A problem is formulated as undesired interaction between two components. For instance, a mechanical field keeps coffee in the cup but the same field make coffee particles stick to the cup. The same interaction can be described as a coupled harmful and useful. It would be nice if the coffee particles could not stick to the cup at all.  

To obtain a solution to a problem represented in terms of SFM means that the physical structure which contains the undesired interaction (source SFM) has to be transformed into a structure in which the desired interaction is achieved (target SFM). An inventive standard defines such transformation patterns.  

The original term "Inventive Standard" introduced by Altshuller means that there is a common, or standard method to solve different problems which result in identical problem models. To solve a problem with inventive standards, there is no need to formulate a contradiction.  

An inventive standard consists of two parts. The left part specifies conditions and a problem: what type of the source substance-field model is and what restrictions on introduction of additional components are. The right part shows a pattern of a solution.  

A primary inventive standard is: If there is an object which is not easy to change as required, and the conditions do not contain any limitations on the introduction of substances and fields, the problem is to be solved by synthesizing a SFM: the object is subjected to the action of a physical field which produces the necessary change in the object. The missing elements being introduced accordingly (Fig.5). 
  

According to the described model of the problem we have to apply the following inventive standard: If there is a SFM which is not easy to change as required, and the conditions do not contain any limitations on the introduction of additives to given substances, the problem is to be solved by a transition (permanent or temporary) to an internal complex SFM, introducing additives in the present substances enhancing controllability or imparting the required properties to the SFM.  

Solution: It is proposed to insert an exothermic substance into the gap beforehand that will produce extra heating of the powder without increasing the arc intensity (Fig.7).  

Bridging a gap between science and technology  

Another TRIZ problem solving technique is a pointer to physical effects. While inventive principles and inventive standards do not produce recommendations in terms of what particular physical fields and substances should be used to solve a problem, the Pointer to Physical Effects establishes links between specific physical effects and technical functions the effects are capable of delivering.  

Studies of the patent collections indicated, that inventive solutions are often obtained by utilizing natural phenomena that were not used previously in a given area of technology. Knowledge of natural phenomena often makes it possible to avoid the development of complex and unreliable designs.  

For instance, instead of a mechanical design including many parts for precise displacement of an object for a short distance, it is possible to apply the effect of thermal expansion to control the displacement.  

Finding a natural phenomenon that would be capable of meeting a new design requirement is one of the most important tasks in the early phases of design. However, it is nearly impossible to use descriptions of natural phenomena in a form as they are presented in handbooks on physics or chemistry. The descriptions of natural phenomena available there represent information on certain properties of the phenomena from a scientific point of view, and it is unclear how these properties can be used to deliver specific technical functions.  

TRIZ Pointers to the effects bridges a gap between engineering and science. In TRIZ Pointers, each natural phenomenon is identified with a multitude of technical functions that might be achieved on the basis of the phenomenon.  

The search for effect is possible through formulation of a problem in terms of a technical function. Each technical function indicates an operation that can be performed with respect to a physical object or field. Examples of the technical functions are "move a loose body" or "change density ", "generate heat field", and "accumulate energy".  

A fragment of the pointer to physical effects is shown in Table 2.  
  

Table 2. Fragment of the pointer to physical effects.

   

Example. How to accurately control the distance between a magnetic head and a recording surface of a tape?  

In the TRIZ pointer to physical effects, the function "to move a solid object" refers to several effects. One of the effects is the physical effect of magnetostriction: a change in the dimensions and shape of a solid body made of certain metal alloys during magnetization.  

The magnetic head is fixed to a magnetostrictive rod. A solenoid generating magnetic field is placed around the rod. A change of the magnetic field’s intensity is used to compress and extend the rod exactly to the required distance between the head and the recording surface.  

   

In addition to the Pointer to physical effects, TRIZ offers pointers to physical and geometrical effects, organized in a similar way. 

Advantages of using TRIZ.  

As shown by numerous industrial case studies, TRIZ helps to considerably accelerate the new product development process by quickly generating new solution concepts. This is possible due to the following advantages of the TRIZ methodology:  

• Since inventive design is a knowledge-intensive process, success of inventive design depends on how fast the needed knowledge can be found. TRIZ helps to organize the fast search for needed knowledge.
• TRIZ provides a systematic access to the previous experience of many generations of inventors. This experience is generalized and presented in a form of inventive design rules and guidelines.
• In some cases, it might be clear what function is needed but unclear what physical principle can be used to deliver the function. To organize and guide the search for proper physical principles, TRIZ pointers to natural phenomena and effects are used.
• All design products evolve over the time according to the same domain-independent trends. These trends are used for effective problem solving as well as for forecasting the further evolution of a specific design product.
• TRIZ does not replace human creativity. TRIZ restructures the thinking process of a designer and provides fast access to the needed knowledge, but it does not solve problems independently of the designer.
• No previous inventor's skills are needed to effectively solve new inventive problems.

• TRIZ does not provide exact recommendations on how to formulate contradictions with respect to a particular problem. As a result, a contradiction is constructed ad-hoc since no analysis of a prototypical design is performed.
• To identify an inventive principle, which has to be used for solving a problem represented as a specific conflict, the conflict has to be reformulated in terms of generalized engineering parameters. However, this can only be done intuitively since no translation technique is available in TRIZ.
• Inventive principles and inventive standards do not propose a solution to a given problem. They only refer to a direction, which was used to solve a similar problem before.

Computer Aided TRIZ and CAD/CAM software  

Recently, a number of software packages supporting design problem solving with TRIZ have been developed. Among them are TechOptimizer^tm (Invention Machine Corp, MA, USA) and Innovation Workbench^tm (Ideation International Inc., MI, USA). Although both packages incorporate different approaches to representing TRIZ knowledge and organizing the problem solving process, they form a new category of computer-aided design tools, which support a conceptual phase of engineering design.  

While traditional CAD/CAM systems focus on processing and computing geometrical and material information about specific designs, TRIZ-based software packages provide access to previous inventive experience stored in the form of inventive principles and indexed physical knowledge. According to a given problem formulation, TRIZ-based packages propose information on what a structure of a design solution should be rather than what form and geometry the solution should have. 

In summary, TRIZ-based packages organize mapping between the function and structure of a concept which is still to be found, whereas CAD/CAM systems map functional and geometrical specifications directly onto already known design solutions stored in the database.  

In addition, CAD/CAM systems propose specific, "ready-to-manufacture" descriptions of solutions that makes such systems relatively easy to learn and use. TRIZ-based packages are well-organized interactive systems which help with finding general recommendations on how to solve problems, or at best, indicating what physical principles to use. A designer should be able to interpret this information and translate it into a feasible solution. No sufficient computer aid has been available so far to support this step. This causes certain difficulties when using the  software by inexperienced designers, since the gap between general recommendation and a specific solution can be very large. It is our belief that to be accepted by a wide audience, TRIZ-based software has to bridge this gap and be able to generate solutions in terms of specific problems instead of displaying general recommendations.  

On the other hand, even existing packages can be of a great help if a designer is familiar with basic TRIZ principles. 

Conclusions  

Since TRIZ is comprised of a large number of empirical rules, it is difficult to evaluate from the point of view of exact sciences. Unlike fundamental sciences, TRIZ is not based on the axiomatic approach and does not include formal means for problem solving and verification of results. Instead, its techniques resulted from a comprehensive study of previous engineering experience that does not guarantee that the techniques will be applicable to every situation that may occur when designing new products. No proof of absolute applicability is possible due to the heuristic nature of TRIZ.  

On the other hand, TRIZ discovered a number of principles and introduced new concepts which, although have not been formalized yet, have proven their applicability for solving practical engineering problems and considerably accelerating the process of new product development. This fact should not be neglected when studying TRIZ. Many years of experience with using TRIZ indicated that the discovered patterns and principles can be successfully applied to solve virtually any inventive problem. For this reason, TRIZ has rapidly became a part of the engineering curriculum worldwide as a general methodology for conceptual design of new products and developing new technologies. 

In summary, major contributions of TRIZ to innovative engineering are:   

• TRIZ discovered a systematic nature of technology evolution and described a number of domain-independent evolution trends.
• TRIZ introduced a new classification of design solutions.
• TRIZ proposes to regard a contradiction as a cause of inventive problems and states that inventions result from eliminating contradictions.
• A set of basic principles for contradiction elimination was proposed.
• Access to the basic principles was organized in a systematic way.
• TRIZ proposed to model design products in terms of substance-field interactions and apply generic patterns to transform the physical structure of products.
• TRIZ proposed a novel way to relate physics knowledge and technical functions.
• TRIZ introduced a range of operators for tackling mental inertia of a designer.

TRIZ: The Right Solution at the Right Time: A Guide to Innovative Problem Solving, by Yuri Salamatov, (Valeri Souchkov, ed.), Insytec B.V., February 1999, 256 pages, ISBN 9080468010. 

Creativity as an Exact Science, by G. Altshuller, Gordon and Breach  Science Publishers, 1984/1988, 319 pages, ISBN 067721305 (currently out of print). 

40 Principles: TRIZ Keys to Technical Innovation, by G. Altshuller, Y. Fedoseev, Paperback - 141 pages 1 edition Vol. 1, Technical Innovation Center, Inc.; ISBN: 0964074036. 

And Suddenly the Inventor Appeared: TRIZ, the Theory of Inventive Problem Solving, by G. Altshuller, Paperback 2nd edition, May 1996, 171 pages, Technical Innovation Center; ISBN: 0964074028.