Acoustic Analysis and Appliances
New regulations and materials are giving acoustic analysis a bigger role in appliance design.
Appliance design engineers have spent decades refining their products’ sound profiles to meet consumer demands for machines that work without drowning out conversations, causing headaches or shaking the house.
As deft as they have been at managing sound, however, today’s appliance design engineers face challenges that their predecessors did not. Government regulations and changing social dynamics are conspiring to alter the basics of designing products with appropriate sound profiles.
More people are living side-by-side with their appliances in smaller spaces, so they want quieter machines. Quieter, though not completely silent. They want enough sound to confirm the refrigerator is working or the washing machine has completed its cycle, but no more.
At the same time engineers are trying to strike that balance, government agencies are mandating greater energy efficiency and “end of life” design that minimizes waste and maximizes re-use. Throw cost, style and size into the mix, and engineers face a tangle of conflicting priorities.
Resolving that conflict is possible, given the right tools. Acoustic simulation technology gives engineers insight for developing products with appropriate sound profiles while balancing other design considerations.
Though not widely used in appliance design in the past because of its cost and complexity, acoustic simulation software is getting cheaper and simpler at just the time that appliance designers need it. There are a variety of ways to incorporate acoustic analysis into appliance design processes without taking on more overhead expenses—software licenses, training, maintenance, etc. The result is giving engineers access to acoustic simulation without requiring them to become acoustic simulation experts.
Balancing design priorities
Designing for greater energy efficiency and smaller environmental impact often requires integrating components made of new materials—plastics, carbon fiber composites, lightweight new metals—into appliance designs. Lighter materials vibrate more than heavier materials, don’t filter sound as well, or filter sound differently than traditional materials.
Engineers’ lack of experience with new materials makes it difficult for them to predict the materials’ acoustic behaviors before prototyping. Acoustic simulation technology can help engineers model and adjust their products’ sound profiles before they enter the latter stages of development.
Most of the major acoustic simulation software on the market today performs tasks directly relevant to appliance design. These include analyzing sound fields in cavities, analyzing sound radiation, and modeling absorbing surfaces and interaction between structure vibration and sound field. With the help of acoustic simulation, engineers can determine the sound radiation created by vibrating structures like pumps, compressors, fans, electric motors and loudspeakers. They can also model sound propagation through complex media to analyze how well it absorbs sound.
An ongoing trend that can ease the transition to using acoustic simulation is to embed the sound radiation analysis at the end of a multi-body analysis, which is a technology that most design engineers are familiar with through their daily design work. As such, engineers who are not acoustic experts can easily get a first insight into the sound behavior of their products. That’s especially important when transitioning from an isotropic material with consistent properties (usually steel) to anisotropic materials with variable properties, such as carbon-fiber composites.
Today, however, the best examples of integrating acoustic analysis into design processes are still found at aerospace and automotive companies that can afford the high-priced analysts who work with today’s acoustic simulation software. Despite the difference in engineering resources between aerospace and automotive companies and the typical appliance design group, the former can still provide good acoustic analysis integration models that can be adapted to appliance design.
Strategies for ppliance companies
Aircraft manufacturer Airbus is one of the companies that has successfully “democratized” access to sophisticated acoustic simulation technology. Airbus has implemented high-end acoustic simulation software on its network that enables engineers to submit calculations and then receive answers from analysts via an in-house-developed automation platform.
The Airbus system gives every engineer on-demand access to acoustic simulation, but does not require engineers to become simulation experts or even power users. Analysts using high-end simulation software perform the calculations and provide design engineers with the results. As a result, Airbus is more easily able to comply with the stringent noise control regulations that restrict flights at airports around the world.
The fair question at this point is how Airbus’ experience is relevant to appliance design. Airbus has about 10,000 engineers who spend years designing a single product. How can an appliance company with, for example, 100 engineers designing 10 products at once possibly follow suit?
Much more easily than that comparison suggests. Airbus proved that it’s possible to integrate acoustic analysis into product development, but not everyone has to do it the Airbus way.
The amount of analysis that aerospace and automotive engineers need would be redundant, if not outright wasteful for an appliance company. An appliance design engineer might only need an occasional analysis to make sure they’re within their intended performance range, as opposed to the frequent acoustic analysis an automotive or aerospace engineer needs. There are strategies for providing that information without investing in a top-to-bottom acoustic simulation program that an appliance company might not need.
The first and most obvious solution is outsourcing, which is as simple as sending computer aided design (CAD) models to an analyst firm and receiving results back. This approach would keep overhead expenses manageable for a company that doesn’t often make substantial changes to its products but wants to maintain their sound profiles. They might only need occasional acoustic simulation to verify their sound profile.
Companies that re-design more often and more extensively, or who don’t want proprietary design data outside their own walls, need an in-house solution that won’t break the bank.
One option for them is to contract with an outside analyst to create acoustic models of each product according to the company’s design best practices. Engineers can use the models as benchmarks to estimate the effects of new materials and designs on the products’ sound profiles.
Some companies need a more interactive system that enables engineers to run simulations. These companies can purchase a single license of an acoustic simulation solution, train one or two engineers to use it, then use them as an in-house service bureau to support the rest of the engineering staff.
For companies prepared to take on an aggressive acoustic analysis program that involves their entire engineering staffs, acoustic analysis software will be reasonably priced and as easy to use as a desktop CAD program within a few years—if not within the next few months. They will be able to equip their staffs for much lower initial outlays, training and maintenance costs than they ever have in the past.
With the advent of new materials and design imperatives, most manufacturing companies need some form of acoustic simulation to maintain their products’ sound profiles. A consumer product probably won’t fail because of a flawed sound profile, but it will definitely be at a disadvantage against competitors with well-crafted sound profiles.
Appliance companies need to know in advance whether the shutter click of the digital SLR camera sounds enough like a mechanical SLR to satisfy serious photographers. They need to know the vacuum won’t wake up the neighbors’ baby, and that reducing the refrigerator’s weight won’t make the compressor too loud to fade into the background.
Integrating acoustic simulation technology into their design processes provides manufacturers with that insight. They don’t need the resources of a multinational aerospace company to do it. They just need to know that they have options for understanding their products’ acoustic behaviors without raising their costs.