Zgomot si vibratii

As machines and equipment have become more refined, consideration of noise and vibration has become key to developing a class leading engine. Perkins has a strong capability in Noise Vibration and Harshness (NVH), both analytically and in test. Close working relationships with all areas right from initial concept design through to customer machine development makes this a dynamic and diverse area. Noise, vibration and harshness (NVH) all concern the study of oscillating objects, but they are subtly different from each other.

Noise
Noise is the measurement of the amount of energy transmitted to the air by an engine or machine. The noise levels of both engines and machines can be measured in semi-anechoic chambers with microphone arrays and the latest high-speed data-logging and analysis equipment. In its work supporting Perkins’ various customers, the NVH team often carries out legislated machine drive-by noise tests. Tools such as acoustic intensity mapping and combustion/mechanical noise separation can then be used to identify the best method of noise reduction.

Vibration
Much of the team’s work is involved in supporting the development of new engines, ensuring that vibration levels are within acceptable limits to prevent component failure. Noise-from-vibration studies (a field in which the team has considerable experience) are often used to identify noisy components. These components can then be redesigned to reduce overall engine noise.

Harshness
Noise and vibration levels are directly measurable, and are therefore objective. Harshness is subjective, in that it involves making engines and machines sound better. The noise in question is recorded using a binaural head system, and the data is then processed by specialised software to predict the effect various noise treatments would have on the overall radiated noise. A panel of assessors chooses the preferred noise, and noise packages are then specified from these results.