The engineering discipline of Airframe Fatigue and Damage Tolerance (F&DT) is used to define critical structural component lives, and produce an inspection and maintenance schedule to eliminate structural failure. The Damage Tolerance concept in particular has been the major contributor to the massive reduction in aircraft structural failures over recent years.
STRAND maintains a dedicated F&DT team which has performed calculations to support initial design, check stress, test and product development for all the major airframe manufacturers. For a list of customers and the products covered refer to the next section.
Airframe components analysed include wing spars, covers, control surface mountings, and tip attachments, as well as major components such as landing gears.
In addition STRAND has been involved in the development of design and test load spectra, and assessment of main airframe fatigue tests and health monitoring and operational load measurement systems.
STRAND has extensive experience of industry methods and computer programs, and a comprehensive in-house computer program suite. Team proficiency is maintained through self-assessment and extensive training procedures.
The A400M Spoilers and Ailerons F&DT Analysis is an example of F&DT work completed by Strand.
This project was the certification analysis for fatigue and damage tolerance (F&DT) of the spoiler and aileron support structure of the A400M. The analysis was challenging because the spectrum was very large and exceeded the capability of existing software to accept such a large spectrum. The spectrum also posed challenges in terms of data management and data handling. This was solved to some degree using in house automation tools which allowed manual checking of the data after being processed. Standardisation of the file names and data set conventions was also employed to allow all engineers involved to easily manage the spectrum. The use of automation and standardised conventions allowed effective coordination between the engineers minimising confusion and potential errors.