Reducing acoustic simulation prototyping time by 94 percent while enhancing brand attributes for luxury golf clubs

A sound priority

Although signature sounds that create immediate brand recognition – and the emotional link that goes with it – are common in the mobility market, they are now popping up in unexpected places such as MAJESTY GOLF clubs, a luxurious Japanese brand with a bespoke customer base.

“The majority of Majesty clients are golfers with the means to play some of the most prestigious courses in the world,” says Hideki Kimura, chief product officer, MAJESTY GOLF.

“We want them to be able to play with confidence, which is why we place such importance on acoustics and the signature sound of our clubs. The sound of a great drive is music to the ears of any golfer.”

“Our work on the Majesty clubs’ acoustic signature starts during the concept stage,” says Shuhei Tanibuchi, research lead, MAJESTY GOLF. “It’s one of the first things that we start to think about when we design and engineer a new series of clubs.”

More than just luxury

MAJESTY GOLF produces one of the most expensive set of clubs, but they aren’t just about luxury: They are also known for outstanding performance and technical excellence.

For more than 50 years, Japanese craftsmen, designers and engineers have been blending innovation and artisanal skills into these clubs. The company uses high-end materials such as titanium, ultra-lightweight alloys and composites, and luxury finishes like pearl coatings, laser-etching and gold-plating on certain series.

“Many customers see Majesty clubs like works of art as well as sports equipment,” says Tanibuchi. “They value the craftmanship, the exceptional quality and the material choice. Any time we save in the engineering development process can be spent on handcrafting and designing more bespoke club models.”

Finding the right sound

This investment in artisanship extends to R&D and overall performance engineering. In addition to adding weight for stability and accuracy and designing face angles for straightforward performance, the engineers also design the sound the club makes when it strikes the ball.

“Our clubs are for moderate-swing-speed golfers who play mostly for the pleasure of the sport and expect excellence in their choice of equipment,” explains Kimura. “Our innovative technology includes acoustic signature or impact sound. Not only do you feel in your hands that you nailed the shot, but you also hear it.”

Predicting the impact sound in the concept stage

When they start working on a new club, Tanibuchi and the engineering team use Siemens Digital Industries Software’s NX™ CAD software for the design. Then the team makes a mesh to run structural analysis in Simcenter™ 3D Structures software in conjunction with the Simcenter Nastran solver. This is followed by a complete acoustic calculation in Simcenter 3D Acoustics software. The R&D team uses the acoustic simulation tool for both frequency response analysis and transient response analysis – depending on the accuracy and interaction required. Design and engineering data is primarily managed in Teamcenter® software.

Simcenter, NX and Teamcenter are part of the Siemens Xcelerator business platform or software, hardware and services.

“When you are studying the sound of an iron, you have more metal,” says Tanibuchi. “It is an easier simulation. But with some woods or drivers, you have a hollow structure and air inside, for instance, a cavity, so it’s a more complex exercise to connect the wall and air vibration effects on the sound.”

This simulation-driven design solution based on NX and Simcenter lets the R&D team combine complex tasks like modal analysis, material selection, structural studies and impact sound analysis, all with a digital twin early in the process. This helps the team predict impact sound prior to molding the first golf head prototype.

“We knew we needed to push the limits of technology when it came to designing a signature impact sound for MAJESTY clubs,” states Shuhei Tanibuchi, Research Lead, MAJESTY. “As major NX users, we really appreciate the power of the Siemens tools and the seamless design possibilities. For our next step into digital acoustic engineering, we knew we needed the best possible tools the market could provide. This is why we turned to Siemens and our Siemens partner, Digital Process.”

A different approach

Previously, acoustic engineers and others created their own impact sound simulation models using traditional modal analysis techniques and sound plots to predict and study the acoustic signature on the prototype.

“This was an entirely new field so it was quite challenging,” says Tanibuchi. “In the beginning, it was trial-and-error. “It took the team over a year to create three models to simulate the probable acoustic sound and confirm it with the actual sound.”

“With classic techniques like the natural frequency values obtained by modal analysis, it’s difficult to define an impact sound for certain club heads early on because the resonance factor is more dominant, especially for the driver head,” explains Motoyuki Nagawa, acoustic engineering expert, Digital Process Ltd. (a Fujitsu company).
“Even if two driver heads have the same natural frequency, the response can be drastically different depending on material properties, shape and damping characteristics.”

Meeting design goals

The R&D team developed tools that could help balance various attributes and save time and effort in the development process.

Working closely with Digital Process, who provided an expert team to help develop the acoustic simulation software tool, the MAJESTY GOLF engineers quickly designed and simulated signature sounds before molding the first prototype of the club.

“Our priority is to maximize the performance of every club,” says Tanibuchi. “This automatically places some restrictions on what we can do acoustically with our impact sound. There is also the artisanal side of things – the appearance to consider and this also causes restrictions for the sound signature.

“It takes two to three months to create a prototype club to test the sound. If it doesn’t sound right, there is wasted cost and human labor. We thought, ‘Why not create a simulation tool to shorten the development time cycle and reduce the need for a physical prototype?’ That’s why we created this acoustic simulation system.”

Devising an acoustic simulation system

The acoustic simulation system, which is based on Simcenter 3D Acoustics, helps the team balance the brand-critical attributes – aesthetics, luxurious material choices, quality performance requirements and impact sound. Early in the design phase, they select the materials and see the effects on the structural characteristics of the golf head and how this will affect impact sound. The Simcenter 3D model enables them to predict the correct impact sound prior to starting to make the mold, cast or 3D print for the first physical prototype.

“Acoustic simulation is the only way to completely understand the acoustic science behind the sound of each Majesty club series,” says Nagawa. “We have all the data, all the amplitudes and frequencies of the various shapes and materials. This allows us to create a balanced sound amplitude that fits all the design elements required for performance and appearance.”

Reducing product development times

Not only does the Simcenter acoustic simulation tool make creating the MAJESTY GOLF sound signature more precise, but it also offers numerous process improvements.

“We’ve been able to reduce our product development process times significantly,” says Tanibuchi. “Acoustic simulation prototyping has been slashed from three months to five days for the first prototype in a mold, cast or 3D printed process, a reduction of 94 percent. If we need to further adjust the mold, which happens with certain clubs, it takes a month. But we have verified a market-ready sound signature using our Simcenter acoustic simulation system in five days – and that impressed everyone on the team.”

Tanibuchi says less prototyping – especially with the materials they use like titanium alloys and some rarer materials like gold – makes their process less wasteful and more sustainable.

Optimizing acoustic simulation

Their customers prefer a powerful metallic sound typically associated with titanium and titanium alloys while meeting performance trends in golf clubs for lightweight carbon fiber and composites. This means the signature sound of a MAJESTY GOLF club is evolving toward higher tones. The team is currently using their acoustic tool to study the effects of new material choices like high tech carbon fibers on the signature sound of the next generation of Majesty clubs.

“Today, we still have so much proprietary knowledge about the Majesty signature sound in our heads,” adds Tanibuchi. “This tool will allow us to create a database of material choices as it relates to acoustic performance.

“In the future, we hope to have a more system-based development approach and link our impact sound prediction system directly to our product development process. It would be great to improve our accuracy and simulate the shape and the materials of a new club the first time and see how it will sound. We would be able to study a 100 percent accurate impact sound early on: What would the club impact sound like if we changed a certain material here or there? This is the type of full system development we expect to do in the future.”

“We are a company that is constantly driven to improve,” says Kimura. “It is not surprising there is still some space to improve our acoustic simulation tool. MAJESTY GOLF is continuously working with the teams at Siemens and Digital Process Ltd to strive toward achieving the ultimate acoustic simulation system solution for the Majesty signature golf club sound.”