Section 7.1. Introduction
The materials tests provide
the basic materials data for structural life analyses and for residual strength
calculations. For the most part, these
tests are conducted as early in the design phase as practical, in order to aid
in the selection of materials and in the sizing of the structure. Materials data covered by this category of
tests include fracture toughness and crack growth resistance properties, as
well as basic tensile, compression, bearing and shear data.
The quality control tests
provide data that support the initial quality design assessments or ensure the
uniformity of the production product.
Requirements for these tests are defined after the preliminary sizing
and the identification of fracture critical parts have been accomplished. Quality control data covered by this
category of tests include equivalent initial quality (EIQ), fracture toughness,
tensile strength and notch tensile strength data.
The analysis verification
tests provide data that define the accuracy of the damage tolerance analysis
tools relative to their ability for predicting the crack growth behavior of the
structure under operational conditions.
These tests are typically conducted during the design analysis and development
testing phase of the contract prior to testing the full-scale structure. Additional testing may also be required
subsequent to the full-scale flight and ground tests to support interpretation
and evaluation of cracking problems.
Analysis verification tests include those tests that are used to verify
stress-intensity factor calculations, residual strength methods, crack growth
calculations and test spectrum truncation procedures.
The structural hardware
tests have two functions: (a) to support the verification of the complete
structural design, and (b) to define those areas of the structure that need
additional attention. These tests are
scheduled so that there is sufficient time to incorporate structural changes
into production aircraft. In fact,
production go-ahead is predicated on achieving one design lifetime of
flight-by-flight loading in the full-scale durability test per JSSG-2006
paragraph 3.11.1. Structural hardware
tests include joint tests, component tests, assembly tests, as well as full-scale
Each of the following
sections will describe one of the four categories of damage tolerant
tests. Test procedures as well as data
reduction methods will be outlined as appropriate. Where the test has been required by JSSG-2006, the appropriate
paragraphs in this controlling document are cited.