Resonant testing machine as table model for dynamic bending load applications testing frequencies 40 300 Hz

CRACKTRONIC

RUMUL RUSSENBERGER PRFMASCHINEN AG

General

Mainly two observations in dynamic material testing were thereasons to develop the CRACKTRONIC

A high number of tests are done with low loads For bending load tests instead of axial loading

(tension/compression) such a small and low cost machine is favorable.

In addition a lot of tests are to be done on small specimens.Evaluations of fatigue crack growth rates are comfortablydone with our crack length measuring system FRACTOMATand our SOFTWARE.

Functional description

The kinematic conditions allow a purebending between the gripping heads.An electromagnetic driven resonator,built as a rotary oscillator, creates anappropriate bending moment. Indepen-dent to the dynamic drive a static moment is possible to be applied to the specimen via a torsion rod.

Dynamometer Torsion rod

Specimen Armature of the exciting magnet

CRACKTRONIC

Main applications

Fatigue tests / S/N-diagrams Fatigue crack growth /

da/dN-curves Precracking of fracture mechanic

specimens also in hot cells manufacturing quality control in

connection with special custom-tailored devices

CRACKTRONICMachine design

The CRACKTRONIC is used for many different testing appli-cations where an easy and fast change of mounted grippingheads is essential.

Due to a conceptual separation of the testing machine into abasicmodule with all drives and easily mountable grippingheads for the specimens a change of the gripping head canbe done within a few minutes. Each gripping head contains acomplete fixation with an adequate sensor and measuringpreamplifier.

Essential features of the mechanical conceptions are besidethe modular design the adjustable magnet which gives muchmore flexibility for testing soft specimens and to realize cus-tom-tailored solutions at cost-saving conditions (for compo-nents, hot cell, corrosion, etc.).

The CRACKTRONIC is equipped with the control unitCREDO and a PC workstation to operate the easy to useRUMUL software.

Control conception

The RUMUL control unit CREDO is designed as a compact adaptive testingsystem. The twin computer conceptallows a consequent separation in func-tions. The operating system runs underWINDOWS. All measuring data are processed on-line by the main controlprogram in the process computer.

Examples of specimens Gripping head for customer designedspecimen

Gripping head for sheet metal tests

Gripping head for hot cell

CRACKTRONIC

SOFTWARE-PROGRAMS

Fatigue tests

Due to the low power consumption (approx. 5 W) and the high testing frequencies theCRACKTRONIC is well suited for fatigue tests.In connection with the RUMUL SOFTWARE different evaluation methods are available;

arc sin p Transformation Weibull procedure Perlschnur (regression) stair case method

There are integrated diagram-functions as wellas ASCII-files for customer made evaluationsoftware available.

Arc sin p Transformation

History-record frequency drop

Frequency drop / load adjustment

Precracking

If fracture mechanics specimens need a fatigue crack (precrack), theCRACKTRONIC is the best solution for precracking of small specimens.

The RUMUL SOFTWARE supports theprecracking procedure efficient and reliable.

The SOFTWARE takes care to reach the final cracklength in several loadsteps to make sure that the procedure is in accordance with standards.

CRACKTRONICSOFTWARE-PROGRAMS

Fatigue crack growth

The CRACKTRONIC, appointed as a cyclic load system forbending specimens, combined with KRAK GAGES and thecrack measuring system FRACTOMAT are an ideal configura-tion for receiving da/dN data. The machine is able to be con-trolled manually via the cracklength indicated on theFRACTOMAT. In connection with a PC and the RUMULSOFTWARE an automated testing procedure (i.e. Threshold)is on disposal. The operator is free to change test modes atany time in order to receive new stress intensity values. Thecurrent da/dN curve is on display during the test.

da/dN diagram

Examples for KRAK GAGES

FRACTOMAT

Applied KRAK GAGE

CRACKTRONIC

Bending testsmounted gripping head for specimensup to 10x10 mm

160 Nm mounted gripping head forspecimens up to 12x24 mm

Bending testson metal sheet

Torsion testsmounted gripping head for torsiontests

Tension/compression testsmounted gripping head for specimens CT 14

CRACKTRONICMini-Charpy specimens

adapter pieces for mini specimens 3x4x27 mm or customized shapes

max. bending moment: 160 Nmmax. dyn. bending moment: 160 Nmmax. stat. bending moment: 100 Nmmax. tension load (with tension/compression module): 8 kN

max. testing frequencies (depending on the mounted head): up to 250 Hz, in stepsmax. oscillating angle (depending on the mounted head): 3, adjustablemax. specimen dimensions for bending: 24x12x120 mm

Dimensions: BxHxT machine: 50x20x32 cm control panel: 50x32x37 cm

Weights: machine: 50 kg control panel: 30 kg

Power supply: 230 V / 6 A

Options: gripping heads for bending up to 160 Nm device for torsion tests on round specimens

(clamping 14 mm / 24 mm) or square shapes gripping head for tension/compression up to 8 kN machine controlled by the oscillation angle (analogous to stroke

control mode in tension/compression tests)

Technical specifications

Gewerbestrasse 10/RundbuckCH-8212 Neuhausen am RheinfallSwitzerlandTelephone ++41 52 672 43 22Telefax ++41 52 672 44 48e-mail rumul@rumul.chHomepage www.rumul.ch

Other well proven RUMUL products

Resonant Testing MachineTESTRONIC50/100/150/250 kN

Resonant Testing MachineMIKROTRON5/20 kN

Resonant System SWINGERefficient equipment foralternating bending load

Crack Length Measuring SystemFRACTOMAT for measuring cracksin fracture mechanics

RUMUL

RUSSENBERGER PRFMASCHINEN AG

MIKROTRON

Resonant Pulsator MIKROTRONfor loads up to 20 kNdynamic stroke up to 4 mmand operating frequencies up to 250 Hz

MIKROTRON resonant testing machine

RUSSENBERGER PRFMASCHINEN AG | Gewerbestrasse 10 | www.rumul.ch | info@rumul.chCH 8212 Neuhausen am Rheinfall | Tel +41 52 672 43 22 | Fax +41 52 672 44 48

General

The MIKROTRON testing machine com-

bines a simple and well thought-out

design with a modern and user-friendly

control system. Many decades of

experiences in the design and manufac-

turing of resonant systems and also the

knowledge of the requirements of our

customers allow to achieve a high level

of reliability in a wide field of applicati-

ons. Due to the unique resonant system,

the pulsator is able to work in an opera-

ting frequency range between 50 and

250 Hz in consuming a significant low

power of less than 0,5 kW. The

MIKROTRON is well established in R&D,

quality control and other testing fields.

Characteristical features of all the reso-

nant type testing systems are:

High reliability

No maintenance for valves, pumps or

cooling

Easy operation

Fast testing procedures due to high

operating frequencies

Low energy consumption

Software with many practical and

user-friendly functions

Control concept

The well established dual computer

approach ensures a clear and easy to

understand Windows-based user envi-

ronment, while the embedded device is

running a powerful and robust Linux ope-

rating system to control all machine tasks

in parallel.

Latest technologies like digital signal

processing, FPGA integration (Field Pro-

grammable Gate Array) etc. have been

used to achieve a most reliable control

system with best long-term stability. The

new and comprehensive self-diagnostic

function informs the operator about

unusual events or inappropriate mani-

pulations and therefore helps to avoid

damages.

If necessary the user can individually

adjust all control parameters. This is

especially useful with complicated or

difficult measurement setups.

The RUMUL application programs run-

ning on the Windows computer use a RS

232 or an Ethernet (TCP / IP) link to com-

municate with the machine. Networking

features like remote access, remote

maintenance etc. are prepared.

MIKROTRON

Legend

1 Magnet for dynamic drive

2 Cross head

3 Oscillating springs

4 Oscillating mass

5 Columns

6 Specimen / component

7 Load cell

8 T-slotted table as counter mass

9 Gear drive for static load

10 Ball screw spindle

Function

The diagram shows the drive for the sta-

tic load in the lower machine frame and

the dynamic drive (magnet) in the upper

part of the machine. The effective load on

the test piece is generated by the two

drive systems, controlled and adjusted

independently. The unique design of the

MIKROTRON resonant system results in

an outstanding large oscillating stroke of

+/- 2 mm and still a light machine which

does not require special foundations.

Frequency response

The diagram shows the frequency beha-

viour of the MIKROTRON, 20 kN version,

depending on the stiffness of the speci-

men. In order to vary the frequency within

the drawn range, the oscillating mass (4)

needs to be changed.

MIKROTRON