Continuous commitment to CAE for a quarter of a century
ASICS Corporation, Institute of Sport Science (ASICS) is very popular in the sports footwear market. This includes both the general consumer and running shoe segments, where ASICS is among the market leaders.
The popularity of ASICS shoes is largely based on their superior functionality, which can be directly attributed to the company’s continuous efforts to improve shoe performance.
One of the major contributors to improved shoe performance has been the aggressive use of computer-aided engineering (CAE). At ASICS, serious commitment to simulation began around 1987.
For 25 years, ASICS professionals – both CAE specialists and other engineers/researchers – have actively utilized various analysis tools. Among these tools, the most significant contributor to performance enhancement has been the use of Femap™software with NX™ Nastran® software.
The CAE effort is led by Dr. Tsuyoshi Nishiwaki, Fellow and senior general manager of ASICS Institute of Sport Science.
Since joining ASICS, Dr. Nishiwaki has strived to implement and deploy the best CAE tools across the product development process.
Before devoting his time to shoe development processes, Dr. Nishiwaki worked on analyzing sporting goods, such as tennis rackets. Dr. Nishiwaki is not only experienced in the use of CAE software, he has personally developed a numerical model that represents the mechanical properties of composite materials.
CAE as a decision-making tool for development direction
Through experience, Dr. Nishiwaki has observed that CAE software is a great tool for decision-making across a number of areas, especially for development direction. He points out, for example, that because of the use of 3D computer-aided design (CAD) in conjunction with Femap with NX Nastran, ASICS has reduced and continues to reduce physical prototypes per project.
He also notes that reducing CO2 emissions is now becoming an important issue at the corporate level, as well as for virtually every manufacturer today. By using CAE early in the development cycle, the production of physical prototypes is significantly reduced, as are CO2 emissions.
“Using CAE effectively to decide product development direction, we estimate we are shortening turnaround by 30 to 35 percent for general development projects,” says Dr. Nishiwaki.
Many CAE users focus on how well analysis results match with experimental results. According to Dr. Nishiwaki, for purposes of shoe design, it is a rare case to have exactly the same results. To do so, all of the required information, such as material properties, constraints and loads must be completely known.
This is particularly true for products like sports shoes, which require factoring in certain physical conditions of the human body, although much of that information is highly variable or unknown.
For example, muscle flexibility/stiffness often varies as a person’s mental state changes. So even if just one of these characteristics is unknown, that often means that one cannot obtain a highly accurate result.
Nevertheless, Dr. Nishiwaki emphasizes how critical it is to use CAE tools to capture the impact of design on shoe performance, explaining that simulation can provide special insight on the design of a shoe’s sole, enabling important decision-making data regarding overall performance to be captured in the early phases of development.
According to Dr. Nishiwaki, it is just this type of use of Femap with NX Nastran that has enabled ASICS to reduce product development time by 30 to 35 percent.
Using subjective metrics to improve objective performance
When Dr. Nishiwaki began his work on sports footwear development, he soon tackled the issue of leveraging subjective metrics using CAE. “Although quite a few biomechanics professionals have been researching human body movement with respect to shoes, these findings weren’t leveraged to improve the shoe development process,” says Dr. Nishiwaki.
To quantify performance metrics that could only be evaluated in physical ways in the past, ASICS established eight domains of functionally: cushioning, stability, flexibility, fitting, durability, grip, weight and ventilation.
ASICS then established metrics within each domain through experiments and hypotheses. For example, to establish metrics for cushioning properties, ASICS hypothesized that such properties are tightly linked to the acceleration of the shin.
Through a series of experiments, the company found that when the sole absorbs low frequency waves, the shoes have better shock-absorbing characteristics. Moreover, with that knowledge in hand, ASICS set about to determine specific cushioning metrics using CAE.
“The design process for shoes is the same, whether it’s for a professional athlete or a casual jogger,” says Dr. Nishiwaki, pointing out, “Actually, shoes for the casual jogger have more performance features.”
According to Dr. Nishiwaki, shoes have two major roles. One is to improve the performance of the user; the other is to protect the user from injury.
For the professional athlete, the second role, protection, is secondary. While protection is meritorious, a professional athlete’s No. 1 priority is to improve performance.
However, for the casual athlete or young person first trying sports, protection from injury is very important.
Moreover, sports shoes for general consumers must serve highly diverse needs, so they must perform well for most individuals.ze in simulation.