Fatigue analysis tools of aerostructures Daniel Dębski, Marek Dębski, Krzysztof Gołoś, Jan Kaźmierski

Spis treści książki

PREFACE.................................................................................................................9
WSTĘP....................................................................................................................10
1. REVIEW, COMPARISON AND ANALYSIS OF FATIGUE
ESTIMATION METHODS OF AIRCRAFT STRUCTURES.................11
1.1. Introduction.................................................................................................... 11
1.2. Fatigue Estimation Methods of Aircraft Supporting Structures..................... 15
1.2.1. Fatigue Calculation Analysis.............................................................. 15
1.2.2. Aircraft Loads Spectrum.................................................................... 19
1.2.3. Fatigue Tests of Selected Elements or Critical Points
of Aircraft Supporting Structures....................................................... 28
1.2.4. Numerical Crack Growth Simulation and Residual
Strength Estimation ........................................................................... 33
1.2.5. Calculation Analysis Procedure of the Fatigue Durability
of the Critical Points of Aircraft Supporting Structures .................... 37
1.2.6. Reliability Coefficients Selection....................................................... 38
Conclusion..................................................................................................... 39
1.3. References...................................................................................................... 39
2. EVALUATION AND IMPROVEMENT OF FATIGUE
ANALYSIS METHODS AND RELEVANT TESTING.............................41
2.1. Fatigue Load Cycle Reduction to Equivalent Cycle
– DGD Loads Reduction’s Hypothesis.......................................................... 41
2.1.1. Introduction........................................................................................ 42
2.1.2. Equivalent Load Cycle....................................................................... 42
2.1.3. Fatigue Life Calculated According to Oding Hypothesis
and According to DGD Hypothesis ................................................... 46
2.1.4. Conclusions........................................................................................ 46
2.1.5. References.......................................................................................... 46

2.2. New Limit Curves of the Complex Stress – State Fatigue Strength.............. 47
2.2.1. Nomenclature..................................................................................... 47
2.2.2. Introduction........................................................................................ 47
2.2.3. Huber-Mises’ Hypothesis................................................................... 47
2.2.4. New Limit Curve................................................................................ 48
2.2.5. Modification of the Gough Limit Curve............................................ 49
2.2.6. Conclusions........................................................................................ 50
2.2.7. References.......................................................................................... 50
2.3. Hypothesis of Loads Cycle Reduction to Equivalent Fatigue Cycle............. 51
2.3.1. Nomenclature..................................................................................... 51
2.3.2. Introduction........................................................................................ 52
2.3.3. Proposed Hypothesis of Discretionary Load Cycle Reduction
to the Equivalent Fatigue Load Cycle................................................ 54
2.3.4. References.......................................................................................... 58
3. DEVELOPMENT OF IDEA OF CONTINUOUS FATIGUE
ESTIMATION OF AIRFRAME STRUCTURES......................................59
3.1. Introduction.................................................................................................... 59
3.2. Theoretical Fundamentals.............................................................................. 60
3.2.1. Reduction of Complex Load.............................................................. 60
3.2.2. Loads Cycles Reduction to Equivalent Fatigue Loads Cycles........... 61
3.3. Realization of the Idea................................................................................... 62
3.4. The Idea Justification..................................................................................... 65
3.5. Possibility of Application and Conclusions .................................................. 68
3.6. References...................................................................................................... 71
4. IDENTIFICATION AND ANALYSIS OF FATIGUE CRITICAL
AREAS OF AIRFRAME STRUCTURES...................................................72
4.1. Selected Elements and Fatigue Critical Areas (FCA)
of Aircraft Supporting Structures................................................................... 72

4.2. Example of the FCA of the Small Aircraft Structure .................................... 73
4.2.1. Identification of the FCA.................................................................... 73
4.2.2. Actions Taken in Order to Solve the Problem ................................... 74
4.2.3. Conclusion.......................................................................................... 78
4.2.4. References.......................................................................................... 78
5. LOADS AND FATIGUE RECORDERS......................................................79
5.1. Purpose Requirements.................................................................................... 79
5.2. Autonomous Fatigue Recorder AFR AROS.................................................. 80
5.2.1. Main Parameters of the Recorder....................................................... 81
5.2.2. AFR Hardware and Software Solutions............................................. 81
5.2.3. Recorder Test...................................................................................... 89
5.3. Examples of AFR – AROS Practical Application ......................................... 91
5.4. The Spectra of Longitudinal Accelerations of a City Bus............................. 98
5.5. Autonomous Loads and Fatigue Recorder – ALFR....................................... 99
5.5.1. Basic Data......................................................................................... 100
5.5.2. Software for Analysis, Development and Presentation
of Data from the Recorder............................................................... 102
5.5.3. Selected Operating Windows of the Software for Analysis,
Development and Presentation of Data from the Recorder.............. 103
5.5.4. In-Flight Testing of the Recorder in an Aerobatic RC Yak -54 Model...107
5.5.5. In-Flight Testing of the Recorder in the PZL M-26 Iskierka Aircraft.....108
5.6. Monitoring System of Structures’ Loads – MSoSL (SMOK)....................... 110
5.6.1. Preliminary Testing........................................................................... 110
5.6.2. Monitoring System of Structures’ Loads (MSoSL).......................... 114
5.6.2.1. Monitoring the Assembly of a Structure........................... 117
5.6.2.2. Structure Operation........................................................... 119
5.6.3. Applications...................................................................................... 120
5.7. References.................................................................................................... 127

6. COMPOSITE JOINTS AS A METHOD OF FATIGUE
STRENGTH INCREASE OF AIRPLANES STRUCTURE – IDEA,
TESTS AND APPLICATIONS....................................................................133
6.1. Introduction.................................................................................................. 133
6.2. The Idea........................................................................................................ 133
6.3. Fatigue and Static Test of Isolated Composite Joints................................... 134
6.4. Tests of a Truss............................................................................................. 136
6.5. Applications ................................................................................................ 139
6.6. References.................................................................................................... 141
7. ESTIMATION OF CUMULATIVE FATIGUE DAMAGE....................142
7.1. Introduction.................................................................................................. 142
7.2. Characterization of Complex Fatigue Loading ........................................... 143
7.3. Energy Based Fatigue Criterion................................................................... 149
7.4. Cumulative Fatigue Damage in Terms of the Total Strain Energy Density....150
7.4.1. Introduction...................................................................................... 150
7.4.2. Energy Based Cumulative Fatigue Hypothesis................................ 152
7.4.3. Conclusions...................................................................................... 155
7.5. References ................................................................................................... 156
8. SURE GLANCE ON NONLINEAR FATIGUE DAMAGE
ACCUMULATION........................................................................................158
8.1. Conclusions.................................................................................................. 163
8.2. References.................................................................................................... 164
9. ABBREVIATIONS AND ACRONYMS.....................................................165

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