Test The Limits

Time to turn down the volume: how heavy machinery companies can tackle noise pollution before their equipment is even built

By Exa

July 07 2016

According the U.S. Environmental Protection Agency, the key to attacking noise pollution is addressing it in the design stage. The Agency states it is much easier to design noise out of a machine before it is built than to absorb or deaden the noise afterwards. Many progressive heavy equipment manufacturers agree and are leading the way in engineering practices that use simulation to optimize their products.


Off-highway machinery and equipment manufacturers are constantly looking for new ways to reduce the noise output of their operations to meet government and local regulations, as well as aid clear and effective communication between their teams on-site. No one wants unnecessary noise from machinery, and advances in CAE are going a long way to improving efficiency and NVH performance in the sector.


The sorts of sounds you might hear near a building site or road work would most likely include that of cooling fans, engine surface vibration, transmissions, mufflers and hydraulic systems all working hard to pierce concrete, shift heavy loads and lay foundations. This is what’s known as ‘total noise’, the cacophony of conflicting sounds that can cause such a disruption to those nearby as well as the health of the operator. Occupational exposure to hazardous occupational noise is a risk to operators, those that must work in close proximity to noise-generating equipment, as well as a concern for the employers who need to protect their workers.


Exa has recently teamed up with U.S-based heavy machinery supplier, Vermeer Corporation, to see if they could help optimize the design of a number of its construction apparatus, to reduce residual noise output and enhance primary functions along the way.


For example, one of Vermeer’s horizontal directional hydraulic drills is used to bore underground channels parallel to the road surface, to make way for piping, cabling and conduits. The power required to burrow into the ground and displace tons of soil, while sufficiently cooling the machinery as it works, generates a considerable amount of excess noise.


To assess the acoustic noise pollution that is created by the drill as it digs underground, Vermeer’s engineers used Exa’s PowerFLOW and PowerACOUSTICS simulation software. Using a fully complex CAD model, engineers use PowerFLOW’s inherently transient airflow simulation to observe the drill bit and the extraction cooling system.


The accuracy of the aerodynamic and aeroacoustic simulations afforded by Exa software meant that Vermeer’s engineers could observe the shape and tone of the sound spectra emitted from the drill – under and above ground by sampling/measuring the noise at numerous virtual locations using virtual acoustic probes. They were also able to find the precise balance for tuning each component of the drill, to allow for the most efficient fan cooling while reducing total noise emitting from the machinery.


The ability to find trade-offs between the aeroacoustic and overall functional performance of its heavy machinery, has led Vermeer to employ Exa’s simulation software suite from the earliest stages of its design phases. This eradicates late-stage, time and budget intensive faults and leads to more efficient component designs which further reduce running costs.


The increasing focus on simulation-driven design within off-highway suppliers’ design practices has direct and multifaceted benefits for the industry, and for society as a whole.


Manufacturers, like Vermeer, have seen their design phases streamlined as numerous modifications can take effect in tandem, rather than independently, avoiding errors or inefficiencies arising elsewhere. They are attacking noise pollution head on, early in the design process as the EPA suggests.  From the operators to those of us out on the street, less noise pollution from more energy efficient heavy machinery is something we can all appreciate.

An interesting paper, Total Noise Analysis of a Directional Drill, was recently presented by Vermeer and Exa at NoiseCon 16 and can be viewed here.