Vibration, vibroacoustic (NVH) and tensometric testing

Vibration tests

BOSMAL conducts various types of vibration tests. Elements tested include:

• body elements,
• car lamps,
• coolers,
• batteries,
• other components.

BOSMAL vibration systems: 36 kN, 80 kN and 125 kN – comparison of parameters

Vibration system 36 kN

Parameters of vibration system 36 kN

• force: 35,6 kN
• frequency range: 4 – 3000 Hz
• maximum displacement: 76 mm
• maximum acceleration: 100 g (sinus/random), 260 g (mechanical shocks)
• maximum load up to: 600 kg
• head-expander dimension: 600 x 600 mm
• slip table dimension: 914 x 914 mm

Parameters of Climats climatic chamber

• internal dimension: 1500 x 1500 x 1500 mm (volume 3,4 m³)
• temperature range (working with vibration bench): from -40 to 160ºC; working alone: from -75 to 180ºC (10K/min)
• relative humidity: from 10 to 98 % RH (at temperatures from 10 to 90ºC)
• rate of temperature change: 10ºC/min (with interior heat distribution)

Resistance to sinusoidal vibration, random and mechanical shock tests

Vibration system working in conjunction with climatic chamber

Vibrations and mechanical shocks are generated by an electrodynamic inductor allowing testing on the vertical or horizontal axes.
The climatic chamber is integrated into the vibration test bench, which permits production of the required temperature/climatic condition during vibration tests.
We provide the appropriate power supply; electric load, media circuits (air, cooling liquids, etc.) depending on the required installation conditions of the object under test.
We have one- or three-axis accelerometers with a wide range of sensitivities (selected depending on required usage); the vibration system has 12 input channels allowing multichannel vibration control to be conducted and measurement of the test component’s response.
We also have great experience in designing and producing vibration brackets.

Norms

We conduct tests (PCA accredited scope) according to the following norms:

• PN-EN 60068-2-6 – Environmental testing. Tests. Test Fc. Vibration (sinusoidal)
• PN-EN 60068-2-27 – Environmental testing. Tests. Test Ea and guidance. Shock
• PN-EN 60068-2-64 – Environmental testing. Tests. Test Fh. Vibration, broadband random and guidance
• VW80000, BMW GS97073-1, Renault 31-07-004, Toyota TSC3000
• and many other manufacturer norms and test programs established with the customer

Testing scope using vibration system

Sinusoidal vibrations (for example, according to PN-EN 600680-2-6) and random (for example, according to PN-EN 60068-2-64)

• frequency range from 4 Hz to 3000 Hz,
• maximum displacement (peak-peak): 76 mm
• maximum acceleration to 1000 m/s² (100 g),
• maximum mass of object tested to around 600 kg,
• dimensions of the sliding table: 914 x 914 mm
• exposure towards vertical or horizontal axis

Mechanical impacts according to PN-EN 60069-2-27 (for example):

• various shapes of impacts (half sinusoid, trapeze, triangle, etc.),
• maximum acceleration to around 2600 m/s² (260 g),
• maximum mass of test object around 600 kg,
• exposure towards the vertical or horizontal axis,
• shock realisation 100 g 11 ms (at loads up to 40 kg)
• shock realisation 100 g 6 ms on the sliding table (at loads up to 10 kg)

Noise and vibration (during road testing)

We perform noise and vibration measurements during road testing, making use of multichannel DAQ devices by firms such as: Brüel&Kjaer, OROS and DEWESOFT.

Analyses 

• Frequency (FFT, CPB, FRF and others)
• Time Domain
• Order
• Torsional vibration measurements
• Operational Deflection Shapes (ODS)
• Overall
• Plots as a function of time, rotational speed, frequency, order, etc.

Transducers

• Single- and three-axis vibration sensors (ICP, charge)
• Non-contact displacement sensors (CAPACITEC)
• laser for measurement of torsional vibrations (Bruel&Kjaer)
• force transducers (PCB), modal hammer (Bruel&Kjaer)
• polarised (200 V) class 1 microphone (Bruel&Kjaer and G.R.A.S.)
• sound intensity meter (G.R.A.S.)

Norms

• UNECE Regulation No. 59
• UNECE Regulation No. 51
• UNECE Regulation No. 28
• PN-ISO 362:2003
• PN-ISO 7188:2003
• Fiat 7.R3000, 7.R2100*

*Customer to provide norms for testing

Zmierzone poziomy dźwięku podczas przejazdu samochodem

Testing resistance to acoustic vibrations

Tests of resistance to acoustic vibrations in accordance with NO-06-A107:2005

• average value of total sound pressure: maximum 135 dB.
• frequency range: 100 Hz – 10 kHz.
• test of objects with dimensions of approx. 40 x 40 x 40 cm.
• sound measurement at a maximum of 6 points around the test object.

Norms

• NO-06-A107
• NO-06-A103

Vibroacoustic device measurements

Main aims of vibration measurements

• evaluation of the effect of vibration on durability
• solving fatigue problems
• evaluation of material noise
• establishing critical work points (frequency, speed, etc.) at which the vibrations of highest amplitude occur
• establishing the main reasons behind excessive noise emissions
• evaluation of wear of machinery components – diagnostics
• limiting vibration with the aim of ensuring safety and comfort

Main purposes of noise measurements

• diagnosis of incorrect operation
• establishing of excessive noise production
• ensuring compatibility with requirements and norms
• ensuring quality
• product development (regarding noise)

Vibroacoustic measurements

• measurements of vibration in gearmotors, window lifters, wiper mechanisms, sunroof mechanisms, etc.
• steering wheel vibration measurements at engine idle
• vehicle door vibration measurements during closing (damping)
• engine and exhaust system vibration measurements
• low frequency vibration measurements using a seismic sensor – for example, in order to evaluate floor vibrations under precise measuring machines
• vibration measurements with non-contact sensors
• vibration measurements with triaxial sensors at temperatures up to 260℃
• analyses: FFT, order, overall, CPB, Time Domain
• acquisition of 32 channels at a frequency of up to 40 kHz
• acoustic pressure level measurements
• spectral analysis of vibration and noise
• establishing the acoustic power of machines and devices in situ
• noise acquisition for subjective evaluations

Acoustic measurements in an anechoic chamber

Anechoic chamber

This acoustic chamber is built in such a way to minimise the level of acoustic background and acoustic waves reflected from the walls and limit the external noise. Sounds from the outside are strongly suppressed due to the walls’ acoustic insulation and the materials used. Internal surfaces are covered in material with strong sound-absorbing properties; the chamber is lined with “porfles” tiles. Lighting and electricity, together with a table allowing set up of the measuring apparatus are located inside the chamber.

Chamber specifications

• Internal dimensions: 3.8 x 6.8 m, height 2.5 m
• Usable volume: 73 m³
• Chamber acoustic background: 20 dB (A)

Norms

• Determination of sound power levels and sound energy levels of noise sources using sound pressure – survey method using an enveloping measurement surface over a reflecting plane (PN-EN ISO 3746).
• Determination of sound power levels and sound energy levels of noise sources using sound pressure – engineering methods for an essentially free field over a reflecting plane (PN-EN ISO 3744).
• other industry norms (manufacturers’ own)

Analyses

• Frequency analysis (FFT, CPB, FRF and others)
• Time analysis (time domain)
• Order analysis
• Overall
• Graphs as a function of time, rotational speed, frequency, order, etc.

Converters

• polarised (200 V) class 1 microphones (Bruel&Kjaer and G.R.A.S.)
• class ICP 1 microphones (PCB)

Measuring apparatus

• We use DAQ equipment from companies such as: Brüel&Kjaer, OROS.

Brüel&Kjaer Pulse 3560 measurment system

• 6 channels:
• Frequency range: 25.6 kHz
• FFT
• Time domain
• CPB
• Order

Class I microphones

Microphones produced by:

• G.R.A.S
• Bruel&Kjaer

Mobile analyser, type 2270

• Frequency range: 25.6 kHz
• FFT
• Time domain
• CPB

Testing the acoustic properties of materials

We provide the following services:

• determination of the sound absorption coefficient in an impedance tube, reverberation room and a small Alpha cabin,
• determination of acoustic insulation (TL) in an impedance tube and joined chambers via the intensity method,
• measurements of other parameters such as acoustic impedance, coefficient of reflection, etc.

Normy:

• ISO 10534-2
• ASTM E1050
• ISO 11654
• ASTM E2611
• ISO 15186-1
• ISO 354
• ASTM C423
• Fiat 7.R7401
• Fiat 7.R0146
• FCA LP.7R065*

*Customer to provide norms for testing

Strain gauge measurements

Strain gauge measurements

Direct measurements of deformation using strain gauges at temperatures up to 200°C. Measurements in quarter-bridge, semi-bridge and full-bridge systems, with frequency ranges as high as 40 kHz.

Possibility of recording the signal for later analysis.
Static, quasi-static and dynamic measurements.

Aims of strain gauge measurements

• comparison of real values with computational values,
• ensuring repeatability fatigue tests (on various rigs),
• determining the causes of formation of premature cracks,
• indirect force measurement of the system.