Author: U.S. Army Air Mobility Research and Development Laboratory. Eustis DirectoratePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Helicopter Fatigue Load and Life Determination Methods
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 74
Book Description
Fatigue life estimation of helicopter dynamic components is a complex process that is currently achieved through many different methods. The objective of this study was to review existing methods and to develop a standardized method that could be used by the Army for reliably predicting operational life. This report presents results of a detailed review of fatigue life methods used by five helicopter manufacturers as determined by site visits and literature reviews. Recommendations for a standardized method are presented in areas of mission spectra definition, flight strain survey techniques, laboratory fatigue strength characterization, and safe-life calculation procedures.
A Comparison of Fatigue Life Prediction Methodologies for Rotorcraft
Author: Fatigue Life Estimates for Helicopter Loading Spectra
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781723053351
Category :
Languages : en
Pages : 112
Book Description
Helicopter loading histories applied to notch metal samples are used as examples, and their fatigue lives are calculated by using a simplified version of the local strain approach. This simplified method has the advantage that it requires knowing the loading history in only the reduced form of ranges and means and number of cycles from the rain-flow cycle counting method. The calculated lives compare favorably with test data. Khosrovaneh, A. K. and Dowling, N. E. and Berens, A. P. and Gallagher, J. P. Unspecified Center CUMULATIVE DAMAGE; FATIGUE LIFE; HELICOPTER PERFORMANCE; LOAD DISTRIBUTION (FORCES); STRAIN RATE; DISTRIBUTION FUNCTIONS; ESTIMATES; PALMGREN-MINER RULE; PREDICTION ANALYSIS TECHNIQUES; RANDOM LOADS...
A Note on Helicopter Rotor-blade Fatigue-crack Propagation Rates Under Equivalent-lifetime Fatigue Loadings
Author: John F. WardPublisher:
ISBN:
Category : Loads (Mechanics)
Languages : en
Pages : 14
Book Description
Fatigue Life Estimates for Helicopter Loading Spectra
Author: Simplified Analysis of Helicopter Fatigue Loading Spectra
Author: NE. DowlingPublisher:
ISBN:
Category : Cracking (fracturing)
Languages : en
Pages : 22
Book Description
In employing the Palmgren-Miner rule for irregular loading spectra applied to notched mbers, it is necessary to employ rain-flow or an equivalent cycle counting method, and also to consider the accelerated damage at low stress levels due to the presence of high-level cycles. Additional interactions between high and low stress levels, which are associated with local notch mean stress effects, also occur and can be specifically analyzed using the local strain approach. A simplified application of the local strain approach is described that results in upper and lower bounds on life being calculated. This is applied with reasonable success to the standard helicopter loading spectra Helix and Felix, and a much simplified version of Helix is proposed that consists of repetitions of a single typical flight.
Scientific and Technical Aerospace Reports
Author: Fatigue in Composites
Author: Bryan HarrisPublisher: Woodhead Publishing
ISBN: 9781855736085
Category : Technology & Engineering
Languages : en
Pages : 768
Book Description
A survey of work on the fatigue behavior of composites dealing with the problems met with by materials scientists and designers in aerospace, automotive, marine, and structural engineering. Including a historical review, standards, micromechanical aspects, life-prediction methods for constant stress and variable stress, and fatigue in practical situations.
Fatigue Testing and Analysis
Author: Yung-Li LeePublisher: Elsevier
ISBN: 0080477690
Category : Technology & Engineering
Languages : en
Pages : 417
Book Description
Fatigue Testing and Analysis: Theory and Practice presents the latest, proven techniques for fatigue data acquisition, data analysis, and test planning and practice. More specifically, it covers the most comprehensive methods to capture the component load, to characterize the scatter of product fatigue resistance and loading, to perform the fatigue damage assessment of a product, and to develop an accelerated life test plan for reliability target demonstration. This book is most useful for test and design engineers in the ground vehicle industry. Fatigue Testing and Analysis introduces the methods to account for variability of loads and statistical fatigue properties that are useful for further probabilistic fatigue analysis. The text incorporates and demonstrates approaches that account for randomness of loading and materials, and covers the applications and demonstrations of both linear and double-linear damage rules. The reader will benefit from summaries of load transducer designs and data acquisition techniques, applications of both linear and non-linear damage rules and methods, and techniques to determine the statistical fatigue properties for the nominal stress-life and the local strain-life methods. Covers the useful techniques for component load measurement and data acquisition, fatigue properties determination, fatigue analysis, and accelerated life test criteria development, and, most importantly, test plans for reliability demonstrations Written from a practical point of view, based on the authors' industrial and academic experience in automotive engineering design Extensive practical examples are used to illustrate the main concepts in all chapters
Development of Fatigue Loading Spectra
Author: John M. PotterPublisher: ASTM International
ISBN: 0803111851
Category : Aluminum alloys
Languages : en
Pages : 242
Book Description