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Load Assumption for Fatigue Design of Structures and Components Counting Methods, Safety Aspects, Practical Application

:	Michael Köhler, Sven Jenne, Kurt Pötter, Harald Zenner
:	Load Assumption for Fatigue Design of Structures and Components Counting Methods, Safety Aspects, Practical Application
:	Springer-Verlag
:	9783642552489
:	1
:	CHF 85.50
:

:	Maschinenbau, Fertigungstechnik
:	English

:	237
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

Understanding the fatigue behaviour of structural components under variable load amplitude is an essential prerequisite for safe and reliable light-weight design.

For designing and dimensioning, the expected stress (load) is compared with the capacity to withstand loads (fatigue strength). In this process, the safety necessary for each particular application must be ensured. A prerequisite for ensuring the required fatigue strength is a reliable load assumption.

The authors describe the transformation of the stress- and load-time functions which have been measured under operational conditions to spectra or matrices with the application of counting methods. The aspects which must be considered for ensuring a reliable load assumption for designing and dimensioning are discussed in detail. Furthermore, the theoretical background for estimating the fatigue life of structural components is explained, and the procedures are discussed for numerous applications in practice. One of the prime intentions of the authors is to provide recommendations which can be implemented in practical applications.

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