Kenji Iino

Reconstructing the Designers Intention for Reusing Failure Information

The function-structure (F-S) Map expresses the high-level structure of a design. It is often used in the early stage of conceptual design and serves as the starting point for a number of design tools like quality function deployment, failure mode and effects analysis, and more. On the other hand, in designing risk products whose failure can result in serious damage to the quality of human health or the society, the designer often uses tools like failure mode and effect analysis or fault tree analysis to detect weaknesses in design before the products are shaped. Failures, nonetheless, take place and cause negative impact to the society. It is then that the designer or other experts review the design to find flaws in the failure analysis tree or find elements or links in the graph that the designer overlooked. In other words, pre-production failure analysis is limited to the designer’s knowledge and insight. This paper proposes a way to make use of failure knowledge with past accident cases by constructing the F-S Map for the failed products and storing the information in a failure database. Designers can then compare the F-S Map for new products with linked representation of past failure cases and realize scenarios of failure he did not recognize or have to design carefully.Copyright

A Fatal Accident Case and Lessons for Entertainment Engineering

On May 5th, 2007, a six-car stand-up roller coaster Fujin-Raijin II, during a ride, dropped one of its two wheel assemblies from the second car. Losing its balance, the second car tilted to the left by about 45 degrees. The rider in the left side of the front row jammed her head between the passenger support structure and the handrail of the maintenance walkway and was killed instantly. The next day, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) instructed a nationwide inspection of similar attractions.Investigations revealed that the main axle had a crack caused by metal fatigue and the owner of the amusement park, bankrupt in 2009, had been running the coaster for 15 years without changing the axle and reporting “in good condition” upon visual inspection only. The applicable law required, and still does, annual testing with magnetic particles, ultrasound, or liquid penetrant. The axle, at the time of its failure, had only about 25% of cross-sectional area remaining intact where the crack had grown. A maintenance worker later reported looseness with the axle fit in the pressure-receiving hole. The fit was originally designed tight to receive the bending force.People pay and wait in long lines for the excitement of unusual thrill from short amusement rides. The rides take passengers through unusual movements and G-forces to make them scream and laugh. Mechanical parts of the vehicles thus are subjected to unusual loading conditions. Machine design for such rides requires serious design reviews, failure analysis, frequent inspection, and thorough maintenance. Engineering ethics call for amusement park owners’ and workers’ awareness of design and operations for an unusual environment.Copyright

Design Creativity Education in an International Engineering Class

Conventional engineering education in Japan encourages students to widen knowledge built upon work and research by our predecessors. Such education has been effective in producing design improvement for higher efficiency and performance, however, not so in coming up with innovative ideas. Building products from within common knowledge cannot surpass the consumer expectation. We earlier reported about our collaboration between mechanical and industrial engineering educators in finding similarities and differences in the designers’ approaches in the two fields. Industrial designers, like mechanical designers, strive to meet the voice of customer (VOC) by dividing and conquering functional requirements. They also, unlike mechanical engineers, place the starting point of new designs outside the knowledge domain in efforts to define products that surpass consumer expectations. We call the starting point a discomforting seed. This paper reports our experience in educating foreign and native graduate students in mechanical engineering to have them recognize the discomforting seeds.Copyright

Abstracting Failure Case Database Information for Detecting Failure Mode

Industrial accidents continue to happen despite rap id technological advancement and they are often cau sed by triggers similar to those of past accidents. If we turn our eyes to the world, especially to the em erging industrial players, we hear news about accidents ca used by phenomena that have already caused similar accidents elsewhere. Industries, as they emerge and grow over hundreds o f years, learn their lessons throughout their histo ries and build rules, regulations, and common knowledge to avoid accidents. Each industry is probably well aware of accidents that took place in its own country, es pecially when the accident led to enforcement of a new law. Nevertheless, we hardly have any knowledge of accid ents in foreign countries unless they were of huge siz s. Japan had a national project of building a database of knowledge and lessons learned from past acciden ts. Failure Knowledge Database (FKDB) went on the Web i n 2005. As of today it still attracts a large numbe r of readers with its over 1,600 failure cases. Our rese arch is targeted at making use of this FKDB by abst racting the knowledge, especially what triggered the accide nts, and comparing the knowledge with functional an d structural elements used in new designs. Design Record Graph (DRG) is a graphical representa tion of the designer’s intension starting from the left with the product functional requirement which itera tively divides into sub-functions to reach a set of functional elements (FE). Each FE maps to a structural element (SE). Then the SEs iteratively combine to form ass emblies and finally the product at the right end. A failure starts from one of the FE-SE pairs and propagates th DRG in both left and right directions to reach the two ends. The propagation leaves a trace of how the poi nt of failure led to disabling the product. For each failure case in FKDB, we identified the or igin of failure, the FE-SE pair that started the ac cident. An FE is abstracted by a verb phrase and a set of n oun phrases, and similarly an SE with some noun phr ases. By limiting the phrases to use, similar concepts ar e described by the same abstracted phrases. A new design has a number of FE-SE pairs and their propagations in the DRG to reach the two ends. The designer can then compare all propagations in the d esign, without the knowledge if any of them are dan gerous, with those in FKDB that are known to have led to ac cidents. We developed quantitative operators to evaluate the similarity between two traces. Our results offer a w y of warning the designer about possible flaws in a n ew design similar with causes of past accidents tha t t e designer has no idea about. Our method of preventin g design failure can apply to other fields for novi ce planners in avoiding failure while still in the pla nning stage. We can further develop the use of know ledge into overseas countries by mapping the limited number of verb and noun phrases into foreign language.

Service Information Database for Consumer Acceptance

Hardly any engineering product is free of trouble and it has to go through service work, corrective or preventive. Fixing a mechanical pencil with a jammed lead is relatively an easy task for a mechanical engineer, whereas maintaining a power plant requires thorough planning, material handling, work order processing, and huge workforce. Naturally service work for large structures require a well designed database. The authors have shown [1] the importance of feeding service information back to the designer for authorization so the serviceperson will not “invent” maintenance work that may lead to product failure. This paper further suggests opening the whole service process to the public. The idea is especially valuable for some industries that need public acceptance, e.g., nuclear power generation. Nuclear power generation is often a subject of debate for public acceptance. This paper discusses two incidents of cover-ups by utility companies that caused large setback in their public acceptance, one case of overreaction triggered by the media showing dramatic accident scenes without explaining what was going wrong, and an example of poor management that cost a utility company its credence with the public. Up to the time of these incidents utility companies, out of the mindset of “Public do not understand our highly technical operation so telling them what is going on just creates confusion,” tended not to fully explain events that may have affected the public. Thanks to the way information flows around the world these days, even though we may not follow the “techy” words, there are those that understand the phenomena and are good at rephrasing the information so we can easily understand them. The utility company in the poor management case, Chugoku Electric Power Company (ENERGIA), in its efforts to recover the public trust, started a new service information system on the web that opens information about troubles and nonconformance in their plants to the public. This paper explains this new system that is currently in operation. It is a total change in the way a utility company interacts with the public. The courageous step by ENERGIA raises the public knowledge and awareness of nuclear power generation and assures security and safety to the society. The INTERNET is making it harder for companies, administration, educational institutions or any other entities to operate without public acceptance. Opening information is a way we all have to get used to in the coming years.© 2011 ASME

Preventing Misuse of Consumer Products

Accidents with consumer products originate from either product defects or misuse. These two explicit causes result from aging degradation, coupled design, or in some cases from causes that are unknown. We analyzed over 600 cases of past accidents with consumer products in the Japanese market. Of the 309 cases of product defects, 51% were caused by aging degradation, and coupled design was responsible for 66% of the 296 cases of misuse. Evaluation, from the viewpoint of axiomatic design, of these coupled design caused misuse cases revealed that over half of them had coupling of the operational functional requirement in the design stage. These cases consist about 38% of the 296 misuse cases. Instead of blaming the user for misuse, if the designer carefully removes such coupling in the design stage, such accidents can be avoided. In the actual design work, changing part configurations, or adding sensors or interlocks can decouple operational functional requirements.Copyright