Load Assumption for Fatigue Design of Structures and Components (eBook)

The authors are experienced engineers in the automotive industry / at a German Technical University.

Preface 5
Notes Regarding the Translation 7
Contents 8
Abbreviations 12
Symbols 13
Loads, Service Loads, Load-Time Functions 13
Counting Methods, Load Spectra, Matrices 14
Analytical Fatigue-Life Estimate 15
Experimental Test Results-Static 15
Experimental Test Results-Constant Amplitude 15
Experimental Test Results-Variable Amplitude 16
Statistics, Safety, Reliability 16
Chapter 1: Introduction 18
Concluding Remarks 22
References 26
Chapter 2: Characteristic Service Stresses 29
2.1 Stress-Time Functions 29
2.2 Causes of Stress 35
2.3 Deterministic and Stochastic Stress-Time Functions 38
2.4 Special Events and Misuse 44
References 46
Chapter 3: Description of the Counting Methods 47
3.1 Basic Principles 47
3.1.1 Classes 47
3.1.2 Range of Restoration and Class Width 48
3.2 Standards 50
3.3 One-Parameter Counting Methods 50
3.3.1 Peak Counting 50
Description of the Method 50
Description of the Counting Algorithm 50
Comment 51
3.3.2 Level-Crossing Counting 52
Description of the Method 52
Description of the Counting Algorithm 52
Comment 52
3.3.3 Range Counting 54
Description of the Method 54
Description of the Counting Algorithm 54
Comment 55
3.3.4 Range-Pair Counting 55
Description of the Method 55
Description of the Counting Algorithm 55
Comment 56
Note 56
Development 57
3.4 Two-Parameter Counting Methods 57
3.4.1 Range-Mean Counting 57
Description of the Method 57
Description of the Counting Algorithm 57
Comment 58
Development 58
3.4.2 Transition Counting 58
Description of the Method 58
Description of the Counting Algorithm 58
Comment 59
Development 60
3.4.3 Range-Pair-Mean Counting 60
Description of the Method 60
Description of the Counting Algorithm 60
Comment 61
Development 61
3.4.4 Rainflow Counting 62
Description of the Method 62
Description of the Counting Algorithm 62
Limitation 65
Comment 65
Development 66
References 67
Chapter 4: Load Spectra and Matrices 70
4.1 Description of Load Spectra 71
4.2 Extrapolation 77
4.2.1 Analytical Extrapolation with the Shape Parameter 79
4.2.2 Statistical Extrapolation for Stationary Processes 81
4.3 Derivation of Spectra from Matrices 84
4.3.1 Transition Matrix 84
Determination of the Irregularity Factor I 85
4.3.2 Rainflow Matrix 89
4.4 Standardised Load Sequences and Spectra 94
References 97
Chapter 5: Comparison of the Counting Methods for Exemplary Load Time Functions 99
5.1 Load-Time Functions Selected for the Investigation 99
5.2 Random Load with an Irregularity Factor I = 0.99 99
5.3 Random Load with an Irregularity Factor I = 0.7 100
5.4 Step Function with Superimposed Damped Load-Time Function 100
5.5 Superimposed Sinusoidal-Sinusoidal Load-Time Function 105
References 105
Chapter 6: Multiaxial Loads and Stresses 106
6.1 Definition of Terms 106
6.2 Measuring and Recording Technology 107
6.2.1 Calibrated Strain-Gauge Measuring Points 107
6.2.2 x-y Strain Gauge or Multiple Strain Gauge 107
6.3 Counting of Multiaxial Load-Time Functions 108
6.4 Counting of Multiaxial Local Stress States 109
References 110
Chapter 7: Time-at-Level and Level-Distribution Counting 112
7.1 One-Parameter Methods 112
7.1.1 Time-at-Level Counting 112
Description of the Method 112
Description of the Counting Algorithm 113
Comment 113
Application 113
7.1.2 Relative Level-Distribution Counting 114
Description of the Method 114
Description of the Counting Algorithm 116
Comment 116
7.2 Two-Parameter Methods 116
7.2.1 Two-Parameter Time-at-Level Counting 116
Description of the Method 116
Description of the Counting Algorithm 117
Comment 117
7.2.2 Relative Two-Parameter Level-Distribution Counting 118
Description of the Method 118
Application 119
References 119
Chapter 8: Application of the Counting Methods 120
8.1 Criteria for the Selection of a Counting Method 120
8.2 Recommendations 122
8.2.1 Graphical Representation 122
8.2.2 Practical Experience 122
References 123
Chapter 9: Analytical Fatigue-Life Estimate 125
9.1 Palmgren-Miner Rule 127
9.1.1 Consideration of the Mean Stress and Stress Ratio 129
9.2 Modifications of the Palmgren-Miner Rule 130
9.3 Comparison Between Calculation and Experiment 132
9.3.1 Results 137
9.4 Relative Palmgren-Miner Rule 139
References 140
Chapter 10: Design and Dimensioning Load Spectra 143
10.1 Determination of Representative Load Spectra 144
10.1.1 Definition of the Relevant Measuring Frequency 144
10.1.2 Recommendations for the Generation of Measuring Spectra 145
10.1.3 Determination of the Necessary Duration of Measurement 147
10.1.4 Recommendations for the Evaluation of Comprehensive Measurements Under Operational Conditions 149
10.2 Example for the Generation of Design and Dimensioning Spectra 150
10.3 Different Procedures for Load Assumptions 151
References 152
Chapter 11: Safety Aspects 154
11.1 Designing and Dimensioning of Structural Components 154
11.2 Safety Concept 159
11.3 Reliability Concept 160
11.4 Scatter of the Strength 167
11.5 Scatter of the Stress 171
11.6 Safety and Engineering 176
11.6.1 Calculation or Test, or Both 176
11.6.2 Cases of Damage Analysis 177
11.6.3 Comparison of the Concepts 180
11.6.4 Differences in the Scope of Application 186
11.6.5 Safety-Relevant Measures 187
References 192
Chapter 12: Load Assumptions in Various Special Fields 196
12.1 Load Assumption in Technical Rules and Standards 196
12.2 Examples in Various Fields 197
12.2.1 Example: Cranes 197
12.2.2 Example: Rail Vehicles 198
General 198
Determination of the Vehicle Weight 199
Determination of the Loads 200
Examples of Load Assumptions 200
Conclusions 201
12.2.3 Example: Bicycles 202
12.2.4 Example: Automobile 203
Operational Loads 204
Exceptional or Special Events 212
Conclusions 213
References 214
Chapter 13: Supplementary References to Publications on Load Assumptions in Various Specialised Fields 216
13.1 General Machine Construction 216
13.2 Plant Engineering 217
13.3 Wind Turbines 218
13.4 Motor Vehicles 220
13.5 Railway Vehicles 225
13.6 Aircraft Construction and Space Travel 226
13.7 Naval and Offshore Construction 227
13.8 Construction Machines and Agricultural Machines 227
13.9 Sporting Equipment 228
13.10 Reliability 228
13.11 Books with Special Emphasis on Load Assumptions 229
13.12 Symposia and Conferences 230
References 230
Index 232