Kistler 9726A20000 Owner's manual

Instruction

Manual

Impulse Force Hammers

Types 9722A(X),

9724A(X),

9726A(X),

9728A20000

and Accessories

ä

002-082e-01.01

(B08.014e)

Page 1

B08.014e-01.01

Operating Instructions

Impulse Force Hammers

Types 9722A(X), 9724A(X), 9726A(X), 9728A20000

And Accessories

Kistler Instrument Corp., 75 John Glenn Drive, Amherst, NY 14228, USA

Phone (716) 691-5100, Fax (716) 691-5226, E-mail [email protected]

Kistler Instrumente AG Winterthur, Postfach 304, CH-8408 Winterthur, Switzerland

Phone (052) 224 11 11, Fax (052) 224 14 14, E-mail [email protected]

Type 97XX Impulse Force Hammers Page 2

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Contents

Section Page

Contents............................................................................................................................................2

1. Introduction ..................................................................................................................................3

1.1 Applicable Products....................................................................................................3

1.2 Purpose of Impact Testing..........................................................................................3

1.3 Why Impact Excitation? ..............................................................................................3

2. Product Description.....................................................................................................................4

3. Operation ......................................................................................................................................5

3.1 General .......................................................................................................................5

3.2 Powering and Signal Conditioning..............................................................................5

3.2.1 Using "Built-in" Power Sources...................................................................................5

3.2.2 Kistler Couplers...........................................................................................................5

3.3 Tailoring the Hammer .................................................................................................7

3.3.1 Tip Selection and Installation......................................................................................7

3.3.2 Using the Extension Mass. .........................................................................................10

4. Measurement Techniques...........................................................................................................11

5. Maintenance and Calibration......................................................................................................12

5.1 General .......................................................................................................................12

5.2 Trouble Shooting.........................................................................................................12

5.3 Repairs........................................................................................................................13

5.4 Cleaning......................................................................................................................13

5.5 Calibration...................................................................................................................13

6. Technical Data..............................................................................................................................13

7. Warranty........................................................................................................................................15

Type 97XX Impulse Force Hammers Page 3

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1. Introduction

By choosing this Kistler quality product you have opted for an instrument

distinguished by precision, long life and technical innovation. Please read

these operating instructions carefully. You will then make the best use of

the versatile capabilities of your quartz impulse hammer. Kistler offers a

wide selection of measuring instruments and all-embracing systems.

• Quartz sensors for force, pressure, strain, acceleration, shock

and vibration.

• Associated signal conditioners and calibrators.

• Electronic control, display and evaluation instruments.

• Piezoresistive pressure transducers and transmitters with

associated signal conditioning.

Kistler can also provide entire measuring systems for special applications

as in the automotive industry, plastics processing and biomechanics. Our

general catalog provides technical information on the general product line.

Individual detailed technical data sheets are available on virtually every

Kistler product.

Worldwide Kistler customer service is at your disposal for any special

questions still open after studying these instructions. Expert advice is

available on your specific application.

1.1 Applicable Products

This manual covers the following impact hammers:

9722A, 9724A, 9726A, 9728A

The impact hammer, along with the appropriate accessories, is supplied

in a convenient carrying case. If a kit was ordered that included couplers,

accelerometers, or other optional accessories, these components are

also included in the case. This manual does not provide information on

the optional accessory items. Please refer to the accessory operating

manuals included with the shipment.

1.2 Purpose of Impact Testing

Impact hammers are used to provide broadband structural excitation

when measuring the frequency response function of a mechanical

system. The pulse produced by the impact provides input energy with a

nearly constant amplitude over the selected frequency range as

determined by the hammer tip and structure under test.

1.3 Why Impact Excitation?

During the past decade, the popularity of impact testing for structural

dynamics testing has grown enormously. When used properly, accurate

results can be obtained in a very easy and convenient way. Very little

hardware is required and the equipment is portable and relatively

inexpensive. Set-up time is reduced since there are no shaker, amplifier

and electronics to set-up at each input point. Since a hammer permits

easier access to hard to reach areas, innovative testing is possible.

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2. Product Description

Kistler offers hammer kits in four sizes and with a variety of force ranges

(see page 14). The user should select the hammer size that is suitable for

the application and has enough mass to excite the structure under study.

Figure 1A: Type 9722A used to excite light to medium structures at

medium to high frequencies, such as disc brakes and

small motors.

Figure 1B: Type 9724A is for testing medium structures at medium

to high frequencies, such as small machinery, aerospace

and automotive structural parts.

Figure 1C: Type 9726A is for testing medium to heavy structures at

low to medium frequencies, such as medium machinery,

mechanical assemblies and vessels or tanks.

Figure 1D: Type 9728A is ideal for testing heavier structures at low

frequencies, such as large machine tools, I-beams and

building structures.

Type 97XX Impulse Force Hammers Page 5

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2. Product Description (Continued)

The carrying case (Figure 1) is designed to hold and transport the

hammer kit, accessories and optional equipment. It is recommended that

the supplied equipment be stored in the case when being transported or

when not in use.

A BNC connector, on the end of the handle is used for signal output and

the load cell (force transducer) power.

3. Operation

3.1 General

Set-up and operation of Kistler impact hammers is easy. They can be

operated directly from nearly all FFT analyzers with built-in accelerometer

power (2...18 mA, Piezotron voltage mode piezoelectric style). A variety

of Kistler couplers are available to power and provide input signal

conditioning.

Multi-channel couplers can be used to power both the impact hammer

and measuring accelerometers. The reader should read the following

operating instructions to ensure satisfactory results.

3.2 Powering and Signal Conditioning

3.2.1 Using "Built-in" Power Sources

Many FFT analyzers and modal analysis systems are available with

internal accelerometer power supplies that provide a convenient means of

operating Kistler hammer kits. The hammer can generally be connected

directly to the input of the FFT without the need for any further signal

conditioning or additional power sources.

The hammers require a constant current supply in the range of 2 ...18

mA. It is recommended that 4 mA be used unless the cable length

exceeds 430 feet (130 meters). Contact Kistler should information on long

cables be required.

3.2.2 Kistler Couplers

Kistler offers a comprehensive line of low noise power supply/couplers for

modal analysis. These couplers can be used with Kistler hammers and

nearly all accelerometers with built-in impedance converters. The power

supply/couplers are variously known as constant current source supplies

or ICP power supplies. The industry also recognizes these couplers as

voltage mode piezoelectric units by the designation Integral Electronic

PiezoElectric (IEPE).

The chart on the following page provides a listing of available power

supplies/couplers. Please request data sheets on specific types.

Type 97XX Impulse Force Hammers Page 6

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Type 5108A Passive coupler. Customer provides power. CE approved

Type 5110 Battery powered single channel coupler with banana

plugs for direct connection to a multimeter and BNC

connection. CE approved

Type 5114 AC/battery powered single channel coupler with LCD

display to monitor bias. LED’s indicate status of sensor

circuit. Portable or table-top use. CE approved

Type 5118B2 AC/battery powered single channel coupler with 1X, 10X,

100X gain and high pass filter switch. CE approved

Type 5134A 4-channel AC powered coupler and amplifier. Selectable

high pass filters and gain. Random noise generator for

testing with FFT analyzer. Remote control and sensing

via RS-232C. CE approved

Type 5148 16-channel rack mountable AC powered coupler with

unity gain. LED’s indicate circuit integrity. Front panel

BNC output connectors.

Type 5350 Sensor simulator for trouble shooting or checking system

performance. It provides an ideal means to confirm

sensor location or detect inoperative cables. Connects

directly to the input of any Kistler coupler or any power

supply/coupler variously known as a constant current

supply or ICP power supply. Output frequencies of 100 Hz

or 1000 radians/second, sine or square wave with

adjustable amplitude.

Table 1: Kistler Power Supplies/Couplers and Accessories

Figure 2: Kistler Type 5114 Coupler is One of Several

Units Designed to Operate with Impuse Force Hammers

Type 97XX Impulse Force Hammers Page 7

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3.3 Tailoring the Hammer

The impact hammer consists of the hammer structure with a stainless

steel head and a piezoelectric force transducer (load cell). An internal

circuit Piezotron impedance converter provides a low impedance, voltage

output. A variety of interchangeable tips and a detachable extender mass

are also included. Refer to previous Figure 1A to Figure 1D which show

the different hammer configurations and accessories.

3.3.1 Tip Selection and Installation

The frequency content of the applied energy depends on the stiffness of

contacting surfaces. The stiffness can be easily controlled by the type of

hammer tip selected. A hard tip produces a shorter duration pulse, (see

Figure 3) thus applying energy to higher frequencies. To obtain the best

test results it is important not to excite modes outside the frequency range

of interest. As a guideline, the roll-off characteristics of the impact force

spectrum should be such that -10 dB to -20 dB attenuation occurs at the

maximum frequency of interest. Table 2 provides information as to the

frequency response of the supplied tips. (A frequency domain plot is

provided for the 9722A, 9724A, 9726A and the 9728A hammers to

provide more detailed tip frequency response information).

Figure 4A: Frequency Domain Plot of 9722A(X) Hammer With Various Tips

Figure 3: Pulse Shapes For

Various Tip Hardnesses

Type 97XX Impulse Force Hammers Page 8

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Figure 4B: Frequency Domain Plot of 9724A(X) Hammer With Various Tips

Figure 4C: Frequency Domain Plot of 9726A(X) Hammer With Various Tips

Figure 4D: Frequency Domain Plot of 9728A(X) Hammer With Various

TipsThe tips and tip adapters screw into the load cell end of the hammer

Type 97XX Impulse Force Hammers Page 9

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(Figure 5). The larger tips can be installed using the hand. A wrench

(Kistler type 1370) is supplied to install the smaller tips. The tips should

be tightened to insure that there is no motion between the tip and load

cell. See table for recommended maximum torque. Do not over tighten.

Tip type 9906 is simply a cover for the 9904A tip that provides a longer

duration pulse. Simply slide the 9906 over the 9904A tip when required.

Never use the hammer without a tip. Operation without a tip may

damage the load cell surface and may affect performance.

Impulse Hammer Type

Type/Spec.

Material

Mass

(g)

Color Torque

in-lbs

(Nm)

9722

9724

9726

9728

9902A Stainless Steel 2.4 20 (2.3)

Frequency Response, Hz

Without Extender 9000 6800 5200 N/A

With Extender 7500 5500 4600 N/A

9904A Stainless Steel 2.0 20 (2.3)

Frequency Response, Hz

Without Extender 2600 2000 1500 N/A

With Extender 2100 1600 1300 N/A

9906 PVC 2.2* Black 20 (2.3)

Frequency Response, Hz

Without Extender 1800 1400 1100 N/A

With Extender 1500 1300 1000 N/A

9908 Plastic 37** Green 20 (2.3)

Frequency Response, Hz (Hard)

Without Extender 1100 800 600 N/A

With Extender 900 650 500 N/A

9910 Plastic 36** Red 20 (2.3)

Frequency Response, Hz (Medium)

Without Extender 650 500 400 N/A

With Extender 550 400 300 N/A

9912 Plastic 34** Gray 20 (2.3)

Frequency Response, Hz (Soft)

Without Extender 450 350 250 N/A

With Extender 350 300 200 N/A

9914 Plastic 40 Black 20 (2.3)

Frequency Response, Hz (Hard)

Without Extender N/A N/A N/A 900

With Extender N/A N/A N/A 700

9916 Plastic 40 Green 20 (2.3)

Frequency Response, Hz (Medium)

Without Extender N/A N/A N/A 600

With Extender N/A N/A N/A 500

9918 Plastic 40 Gray 20 (2.3)

Frequency Response, Hz (Soft)

Without Extender N/A N/A N/A 300

With Extender N/A N/A N/A 250

Table 2: Hammer Tip Characteristics

Frequency range may vary depending on application

* Includes weight of 9904A

** Includes weight of 9228 adapter

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3.3.2 Using the Extension Mass

The amount of energy applied to a structure is the product of the hammer

mass and the hammer velocity. Since it is difficult to control the velocity of

the hammer, the total hammer mass can be easily controlled. Each

hammer is supplied with an extender mass that screws on the top of the

hammer head to add extra energy when required.

To install the extender mass, simply screw the stud into the top of the

hammer head. The extender mass should be tightened by hand with just

enough torque to ensure that it will not come loose during testing.

Do not over tighten.

Hammer Type Extension Mass

Type Number Weight of Extension Mass

(grams)

9722A 9922 50

9724A 9924 125

9726A 9926 250

9728A 9930 750

Table 3: Extension Mass Type Numbers and Weight

Figure 5: Typical Impulse Force Hammer

Type 97XX Impulse Force Hammers Page 11

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4. Measurement Techniques

Proper techniques will lead to more accurate results. If this is the first time

use of an instrumented hammer, the user should be familiar with the

limitations and techniques covered in the many papers on this topic. The

following information is provided to serve as a measurement and pre-

measurement check list.

When collecting data, use the time domain display on the analyzer and

watch for the following:

• Double hits. These are often caused by the hammer bouncing off the

measurement surface. They will appear as multiple pulses on the

analyzer's input time display.

• Watch signal amplitude. Make sure it is adequate to excite the

structure but does not overload the analyzer input. Many FFT

analyzers have a light indication of an overload condition or reject

data when an input overload is present.

• Attempt to match the hammer output voltage to the analyzer input

such that levels are between half and full scale of the analyzer's

range.

• Check the response channels to ensure adequate signal amplitude

without overloads. Again, maximize use of the analyzer input range.

• Use the proper weighting functions. Also use of the improper function

(i.e., Hanning) can cause gross errors in the measurement results.

Use a "Force Window" in the input channel and an "Exponential

Window" in the response channels. Follow the instructions in the FFT

manual for recommended settings of the respective windows. Correct

use of these windows will result in accurate, low noise data. These

window functions are found on most modern FFT/Modal analyzers.

• Take at least four frequency domain averages of the transfer function.

• Check to ensure a coherence >0.9 within the frequency range of

interest.

• Confirm the calibration of the measurement system by using a signal

calibrator-simulator such as the Kistler 5350.

5. Maintenance and Calibration

5.1 General

5.2 Trouble Shooting

Do not try to remove the force sensor from the hammer. This action may

damage the sensor.

Type 97XX Impulse Force Hammers Page 12

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Should the user experience any problems with the hammer load cell or a

Piezotron accelerometer (sensor), the following procedure should be

followed.

Check for possible intermittent cables. Faulty cables are the most

common cause of piezoelectric measurement problems. The application

of a test signal at the hammer end of the cable is an effective means to

determine if the problem is sensor, cable or measurement instrument

related. An instrument such as the Kistler Transducer Simulator type 5350

is ideal for this test.

Kistler couplers are equipped with a bias monitor which can be used to

check the cable integrity and detect malfunctions in the measurement

sensor. Use the bias monitor as follows:

I. With the sensor connected, check for a normal reading on the

bias indicator (normal is approximately 11 VDC).

II. If the bias reading is high:

A. Disconnect the sensor at the sensor end of the cable and

short the cable connector.

B. If the bias indicator reading stays high, replace the cable.

C. If the bias indicator reading now reads low, replace the

sensor.

III. If the bias indicator reads low, disconnect the sensor:

A. If the bias indicator still reads low, replace the cable.

B. If the bias level changes when the sensor is disconnec-

ted, the sensor is defective.

FFT analyzers with built-in sensor power sources generally do not have

bias monitors. In these cases, the user can attach a T connector to the

FFT analyzer and measure the actual bias voltage using an accurate DC

Voltmeter. If the system is operating properly, the bias voltage should

measure approximately 11 Volts. Defects should show-up as in Items II.

and III. above.

If it is determined that the sensor requires repair, please contact Kistler or

your local distributor/representative for repair information.

5.3 Repairs

Field repair is not possible. Please return the instrument to the factory

together with a statement of problems encountered and unit serial

number. Recalibration is recommended when returning a sensor to the

factory. Please contact Kistler for a return authorization number prior to

return.

5.4 Cleaning

When cleaning the sensor, use isopropyl alcohol and lint-free wipes.

Never use air-blast to clean the connector; it may deposit a vapor film.

5.5 Calibration

Specialized force calibration equipment is required to calibrate the

hammer sensor. It is recommended that the hammer be returned to

Kistler when calibration is required. Kistler acceptance test

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instrumentation is in conformance with MIL-STD-45662A. A calibration

certificate will be supplied showing calibration results traceable to NIST.

6. Technical Data

Specifications for the impact hammers are listed in this section on the

next page. Please refer to individual instruction manuals for optional

accessories when ordering complete hammer kits.

Type 97XX Impulse Force Hammers Page 14

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Specification Units 9722A 500 9722A 2000 9724A 2000 9724A 5000 9726A 5000 9726A 20000 9728A 20000

Force Range (For 5V Output) N (lbf) 500 (100) 2000 (500) 2000 (500) 5000 (1000) 5000 (1000) 20000 (5000) 20000 (5000)

Overload Capacity % 500 500 500 250 250 25 25

Hammer Sensitivity, nom. mv/N (mV/lbf) 10 (50) 2 (10) 2 (10) 1 (5) 1 (5) 0.2 (1) 0.2(1)

Resonant Frequency kHz 27 27 27 27 27 27 20

Hammer Mass (head) g (lb) 100 (0.2) 100 (0.2) 250 (0.5) 250 (0.5) 500 (1.1) 500 (1.1) 1500 (3)

Maximum Frequency , -10dB

Without Extender Hz 8200 9300 6600 6900 5000 5400 1000

With Extender Hz 7000 7700 5400 5500 4500 4700 900

Rigidity kN/μm 0.8 0.8 0.8 0.8 0.8 0.8 2.7

lbf/μin 4.8 4.8 4.8 4.8 4.8 4.8 15.4

Table 4: Impact Hammer Specifications

Common Specifications:

Time Constant, nom. 500 sec.

Temperature Range: -20°C...70°C

Sealing Case/Connector: Welded/Epoxy

Type 97XX Impulse Force Hammers Page 15

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7. Warranty

The Kistler Instrument Corporation warrants all Kistler products to be free

from defects in material and workmanship. All such products are

warranted only under normal use and service.

The impact hammers described herein are warranted for a period of 12

months from date of shipment. For cables and adapters the warranty

period is also 12 months.

When returning items under warranty, said equipment shall be returned to

Kistler prepaid. Full details relative to the claim of malfunction shall

accompany the shipment. No action will be taken until these details are

received. Please contact Kistler for a RETURN AUTHORIZATION (RA)

number before returning goods.

Settlement will be made at Kistler's discretion, either through repair or

replacement of the item in question or through issuance of full credit.

Damage occurring through misuse or mishandling, will not be covered by

this warranty.

This warranty is in lieu of all warranties expressed or implied and of all

obligations or liabilities on the part of Kistler Instrument Corporation for

damages following the use or misuse of items supplied. Any unauthorized

disassembly or attempt at repair, shall void this warranty.

No agent or representative is authorized to assume for the corporation

any liability except as set forth within this warranty document.

Our responsibility under the warranty is strictly restricted to the above

provisions and we specifically decline any liability for damages incurred

consequent upon the use or operation of our equipment.

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ERRATA

Types 9722, 9724, 9726, 9728, if subjected to operating

conditions including radio-frequency current in the cabling, may

be affected by higher than normal moise levels on the output

signal.

Several remedial actions, such as the addition of ferrite chokes to

the cable, may be utilized to alleviate this condition.

Disposal Instructions

for Electrical and Electronic Equipment

Do not discard old electronic instruments in municipal trash.

For disposal at end of life, please return this product to an

authorized local electronic waste disposal service or contact

the nearest Kistler Instrument sales office for return instruc-

tions.

Tel +41 52 224 11 11, Fax 224 14 14, info@kistler.com, www.kistler.com

This information corresponds to the current state of knowledge. Kistler reser-

ves the right to make technical changes. Liability for consequential damage

resulting from the use of Kistler products is excluded.

002-331e-09.05

Kistler 9726A20000 Owner's manual

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Kistler 9726A20000 Owner's manual

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