Cryogenic Thermo-Mechanical Fatigue Experiments · 2020-03-14 · Cryogenic Thermo-Mechanical Fatigue Experiments Motivation Compressed Cryogenic Hydrogen (CcH2) and Compressed gaseous

© Fraunhofer-Institut für Werkstoffmechanik IWM

Development of an Experimental Method and Realisation of Experiments

Cryogenic Thermo-Mechanical Fatigue Experiments

2nd International Workshop on Thermo-Mechanical Fatigue

Martin Tandler, IWM

Matthias Metschkoll, BMW AG

Berlin, May12 -13, 2011


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Cryogenic Thermo-Mechanical Fatigue Experiments Content

Motivation

Development of Experiments - Clamping System

Development of Experiments - System for Temperature Control

Results of TMF Experiments

Summary and Outlook


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Cryogenic Thermo-Mechanical Fatigue Experiments Motivation

Compressed Cryogenic Hydrogen (CcH2) and Compressed gaseous Hydrogen (CgH2) are very promising possibilities for energy storage technology.

The components, which are exposed to the very low temperatures of cryogenic Hydrogen, are subjected to cyclic thermal-mechanical stress (loading and unloading of H2) during operation.

For the design of these components, material and life cycle models are required.

The models must represent the material characteristics within the relevant temperature range (-190 °C to +150 °C).

For the adaptation of the models experimental data (LCF and TMF) are required.

► Therefore the development of a testing facility for testing tube specimens was necessary


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Cryogenic Thermo-Mechanical Fatigue Experiments Development of Experiments - Clamping System

Cyclic loading up to ±25 kN

Good axial alignment of the specimen

Axial adjustment of the clamping system

Small thermal mass

Good thermal isolation from the testing machine

Loading of the specimen with liquid N2

Isolation of the specimen to enable external cooling

Specimen in the clamping system with isolation


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Specimen is threaded into the slotted locking key

Clamping nut fixes the specimen tightly into the threaded locking key

LN2 supply through truncation

Clamping System with LN2 truncation

Cryogenic Thermo-Mechanical Fatigue ExperimentsDevelopment of Experiments - Clamping System


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Internal Cooling of the tube specimen using LN2 to -190°C

Heating of the specimen using ceramic radiant heater or induction coil

Bildunterzeile in Arial 12 pt, linksbündig

► High Cooling rate (8 min per cycle) for TMF

► max. temperature range for the TMF tests -190 °C to +150 °C

Cryogenic Thermo-Mechanical Fatigue ExperimentsDevelopment of Experiments – System for Temperature Control

Steel-Specimen with ceramic heater

Al-Specimen with induction coil


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Implementation of outer cooling of the specimen with cold gas reduces temperature within the isolation to -140 °C

Arrangement for outer cooling for isothermal tests

► High Temperature Stability for LCF tests from +20 °C to -140 °C

LN2- tank

LN2-vaporizer unit

Gas preheating

T-Regulator

Vacuum pump

Cryogenic Thermo-Mechanical Fatigue ExperimentsDevelopment of Experiments – System for Temperature Control


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Stress - Strain Curve at RT and -185°C

► Distinct temperature dependency of the yield limit and hardening behaviour

Tension Test of an austenite steel

► Stress induced martensite transfomation at temperatures below -50 °C

metastable austenite

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results - Tension Tests Stainless Steel


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Stress –Strain curve for AL-Alloy at different temperatures

► Distinct temperature dependency of the yield limit

Tension Test of an Al-alloy specimen

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results - Tension Tests Aluminium


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Strain - time in complex LCF-tests

Cryogenic Thermo-Mechanical Fatigue ExperimentsLCF Tests

Complex LCF test program to reduce the tests necessary for calibration of the deformation model

Usage of different strain rates amplitudes and holding times

Adjacent cyclic loading until fracture


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Stress - time in LCF-tests at RT and -100°C

► Significant temperature dependence of the cyclic yield limit and cyclic hardening

LCF-testing of austenite steel

Pre Program Cyclic Program

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results - LCF Tests austenite steel


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Strain - Temperature hysteresis of the TMF - test between +150 °C und -185 °C

TMF-testing of austenite steel

Testing with variable strain hindrance

thmech thmech 2

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results - TMF Tests Stainless Steel


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Strain - temperature hysteresis in TMF - test between +100 °C und -185 °C

TMF-testing of Al-Alloy

Testing at different strain compliance levels

thmech

thmech 2

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results - TMF Tests Al-Alloy

thmech 63.1


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Strain Amplitude vers. Fatigue Life for all LCF-tests

Fatigue life declines with increasing stress amplitudes

Fatigue life increases with decreasing temperatures

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results – Fatigue Stainless Steel


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Strain Amplitude vers. Fatigue Life for all LCF-tests

In principle, the same behaviour applies as that for stainless steel

Fatigue life declines with increasing stress amplitudes

Fatigue life increases with decreasing temperatures

The discrepancies at -80°C and -130°C are currently under investigation.

Cryogenic Thermo-Mechanical Fatigue ExperimentsTest Results – Fatigue Al - Alloy


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A test device for TMF under cryogenic temperatures was successfully developed and established

It has proved to give good experimental results, which can be used for adapting the models used for deformation and thermo-mechanical fatigue.

In future further materials will be tested.

Deformation and thermal fatigue models will be developed for the tested Al- Alloy.

Cryogenic Thermo-Mechanical Fatigue ExperimentsSummary and Outlook


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Martin Tandler, IWM

Matthias Metschkoll, BMW

Berlin, May, 12-13, 2011

Thank you for your attention!

2nd International Workshop on Thermo-Mechanical Fatigue

Documents

Cryogenic Thermo-Mechanical Fatigue Experiments · 2020-03-14 · Cryogenic Thermo-Mechanical Fatigue Experiments Motivation Compressed Cryogenic Hydrogen (CcH2) and Compressed gaseous