Category: Latest Automobile Technology

What Is NVH | NVH Noise | NVH Vibration | NVH Harshness | Noise And Vibration Theory | NVH Basics

NVH Noise, Vibration and Harshness

NVH Noisevibration and harshness, also known as noise and vibration, abbreviated to NVH and N&V respectively, is the name given to the field of measuring and modifying the noise and vibration characteristics of vehicles, particularly cars and trucks.

Noise:

Noise is defined as any unpleasant or unexpected sound created by a vibrating object.

noise and its types - NVH Harshness - NVH Noise car
Noise and its types – NVH Harshness – NVH Noise car

Vibration:

Vibration is defined as any objectionable repetitive motion of an object, back-and-forth or up-and-down.

NVH noise vibration - NVH vehicle - noise and sound
NVH noise vibration – NVH vehicle – Noise and sound

Harshness:

Harshness is defined as an aggressive suspension feel or lack of “give” in response to a single input.

types-of-noise-of-car-nvh-noise-wind-noise-road-noise-engine-noise-exhaust-noise-acoustic-wav
Types-of-noise-of-car-NVH-Noise-wind-noise-road-noise-engine-noise-exhaust-noise-acoustic-wav

Noise and Vibration Theory:

A vibrating object normally produces sound, and that sound may be an annoying noise. In the case where a vibrating body is the direct source of noise (such as combustion causing the engine to vibrate), the vibrating body or source is easy to find. In other cases, the vibrating body may generate a small vibration only.This small vibration may cause a larger vibration or noise due to the vibrating body contact with other parts.

When this happens, attention focuses on where the large vibration or noise occurs while the real source often escapes notice. An understanding of noise and vibration generation assists with the troubleshooting process. The development of a small noise into a larger noise begins when a vibration source (compelling force) generates a vibration. Resonance amplifies the vibration with other vehicle parts. The vibrating body (sound generating body) then receives a transmission of the amplified vibration.

audible-range-of-sound-pitch-intensity-sound-soundwaves-nvh-noise-level
Audible-range-of-sound-pitch-intensity-sound-sound-waves-NVH-noise-level

A sound wave’s cycle, period, frequency, and amplitude determine the physical qualities of the sound wave.

The physical qualities of sound are:

  • Audible range of sound
  • Pitch
  • Intensity

For sound to be heard, the resulting acoustic wave must have a range of 20 to 20,000 Hz, which is the audible range of sound for humans. While many vehicle noises are capable of being heard, some NVH’s noises are not in the audible range.

What causes NVH?

The NVH’s key sources in a car are its engine, drive trains and tires, and also airflow (aerodynamic effect) in its body. Tires seem to be a major noise source because of the vibration generated by their movement, which then passes into the cabin on the suspension mounts.

How can you lower your NVH?

The cancellation of NVH (Noise, Vibration and Harshness) is based on three fundamental principles –

1. Reduce the source of noise and vibration,
2. Isolation from the frame body of the car and
3. Absorption of NVH before entering the cabin as far as possible.

The first approach to minimise the NVH has never been the simplest. For example, aerodynamics play a major role in noise. As air flows through the car’s body, any disruption in its direction causes vibrations of air molecules that transmit the sound.

Car manufacturers work to make more accurate and balanced engines, and to minimise vibration by drive train components. Likewise, tire manufacturers have used various treading patterns and substances to minimise undesirable harshness.

The second and possibly challenging way to minimise NVH is to separate the core frame of the car from the source of vibration. Intensive and costly suspension technology, such as stand-alone, multi-link and hydro-pneumatic systems, isolates the chassis frames and steering column from road surfaces, eliminating vibration and shock.

The Car engine, suspension and exhaust parts are assembled more on rubber and polyurethane bushes than on solid metals to even further eliminate the sources of noise. The softer materials try to avoid vibration transmission.

The Third and  final way to reduce the noise and vibrations as much as possible seems to be the last choice in the NVH battle. In mechanical terms, this refers to steering dampers that absorb the worst shocks caused by poor road surfaces.

With in the cabin, passive sounds can be absorbed through rubber-filled column and double-glazed windows to isolate sound by isolating material fastened on different points in the cabin.

Durability Analysis | Application Of Durability Analysis In Automotive, Aerospace and Wind Turbines

Durability Analysis

Durability analysis involves defect characterization, crack initiation and propagation mechanisms, and long term performance prediction. Durability analysis enables them to identify such points at a very early stage. Such tests can analysis and improve the structural and cyclic strength of a design.

Automotive Durability Analysis

altair-nvh-software-nvh-test-result-of-a-car
altair-nvh-software-nvh-test-result-of-a-car
  • Design more reliable transmissions, drivelines and axles
  • View the whole gearbox as an interacting and flexible system
  • Predict gear, bearing and shaft lifetimes in the design concept phase
  • Accurately and efficiently compare complex gearbox arrangements or concepts such as AMT, DCT, Hybrid and CVT
  • Reduce gearbox weight by using component strength
  • Minimize noise and vibration by influencing the transmission error
  • Identify the weak points in the whole system under realistic load conditions
  • Consider the impact of manufacturing tolerances in the concept design phase
  • Improve the bearing choice by unique accurate prediction of bearing behavior
  • Interact with dynamic solutions for your full vehicle design
  • Predict the effects of generators / engines on the gears and its components in your hybrid system

Durability Analysis in Wind turbine

Wind turbine analysis, Durability analysis of wings
Wind turbine analysis, Durability analysis of wings
  • Understand and benchmark operating load and extreme load scenarios
  • Design gearboxes to meet lifetime targets
  • View the gearbox as one complete system, without the need for sectioning and sectional boundary conditions
  • Analyze the behavior of complex planetary systems within the whole system
  • Accurately predict loads, deflections and interactions of all components
  • Calculate detailed bearing behavior to identify excessive loads
  • Direct loads or reduce misalignment’s to improve the system quality
  • Predict load sharing in the fully flexible system instead of assuming load sharing factors
  • Reduce weight and cost without reducing component lifetime
  • Minimize noise pollution caused by transmission error

Aerospace

Aerospace analysis of wings, Frequency analysis
Aerospace analysis of wings, Frequency analysis
  • Improve reliability for critical parts
  • Reduce gearbox weight
  • Predict bearing behavior under extreme load and climate conditions
  • Optimize gearbox size

Off-highway

Heavy duty engineering analysis, Large gear analysis
Heavy duty engineering analysis, Large gear analysis
  • Design heavy duty transmissions
  • Accurately represent multi-gear mesh situations
  • Optimize gearbox weight without compromising durability
  • Predict system behavior under misuse conditions
  • Compare different lubrication situations
  • Precisely define micro-geometries to avoid edge-loading of teeth under extreme load conditions
  • Consider a split torque system load

Industrial equipment

  • Design for improved reliability in process machinery, material handling, power take offs, speed reducers and production line equipment
  • Improve accuracy of high precision machinery by understanding and predicting system and component deflections
  • Reduce failures in gears and bearings due to precise prediction of misalignment’s

Consumer and office appliance

Casting design, Optimize weight, Wasting material reduction
Casting design, Optimize weight, Wasting material reduction
  • To optimize weight and size of power tools, food processors, washing machines, printers and photocopiers
  • Improve product quality by reducing unwanted deflections
  • Predict changes of working accuracy over a product’s life
  • Design casings that fulfill the requests for look and function simultaneously without wasting material
  • Consider new materials for new or existing product concepts
  • Create technical documentation for certification