Ultrasonic Health Monitoring of Thermoplastic Composite Aircraft Primary Structures

The adoption of composites as aircraft primary structural material has created a real need for a new aircraft maintenance philosophy to enable almost real-time structural condition assessment. It is thus crucial to develop structural health monitoring (SHM) systems capable of performing damage diagnostic and remaining useful life prognostic. At...

Multi-level repair decision-making process for composite structures

This paper details the development of a decision-making model that evaluates the multiple repair levels that a composite structure can undergo, each with its inherent achievable survivability and consequence to operations in terms of availability, costs, and scheduling. The goal of this model is to provide the maintainer an integrated approach...

Residual thermal stresses around bonded fibre metal laminate repair patches on an aircraft fuselage

Residual stresses are present after elevated temperature cure of adhesively bonded patches to cracked aircraft structures. These residual stresses will affect the performance and the durability of the repair. Strain and temperature measurements were taken on a real aircraft fuselage section during and after repair at three locations. Thermal...

A MATLAB program to study gust loading on a simple aircraft model

The present report is part of a "Manual" on aircraft loads, that is being prepared by NLR. It contains a computer program, to be used in combination with "MATLAB4 for Windows" (Student Edition) software, to study aircraft loading due to turbulence. It includes a simple aircraft response model with two rigid and three flexible symmetric degrees...

Aircraft corrosion and fatigue damage assessment (USAF ASIP Publication)

This paper reviews currently available information on corrosion and fatigue in aircraft as a background to discussing the assessment of corrosion and fatigue damage. The main topics are: - aircraft operating environments and loads - corrosion - fatigue - corrosion and fatigue - corrosion and fatigue damage assessment. Aircraft structures are...

Aircraft corrosion and fatigue damage assessment

This report reviews currently available information on corrosion and fatigue in aircraft as a background to discussing the assessment of corrosion and fatigue damage. The main topics are: * aircraft operating environments and loads * corrosion * fatigue * corrosion and fatigue * corrosion and fatigue damage assessment. Aircraft structures are...

The use of load enhancement factors in the certification of composite aircraft structures

In the full scale durability and damage tolerance tests of composite aircraft structures, the US and European certification requirements demand among other things that the number of cycles applied are statistically significant and that the influence of the environment has been taken into account. Several certification methods are described which...

European approaches in standard spectrum development

Typical characteristics of various types of service loading are presented as they were discussed during the establishment of standardised test load sequences. Counting methods are reviewed and a simple and powerful algorithm is given to perform rainflow counting and to store the counting results afterwards. Synthesis procedures are discussed...

Damage tolerance of stiffened-skin structures: prediction and experimental verification

Some consequences of application of the current damage tolerance airworthiness requirements for transport aircraft in designing stiffened-skin structures to be safe under all operational load conditions are discussed. Compliance with these requirements may be shown by analysis supported by test evidence. To provide the designer with analytical...

An introductory course on aircraft loading

The present course book has been prepared as lecture notes for a summer course given at the Technical University of Bandung (ITB) in the summer of 1984. This course took place within the framework of the TTA-79 Technical Assistance Project as agreed between the Governments of Indonesia and the Netherlands. The subjects of the course are listed...

Residual strength of (0, ±45)s and (±45, 0)s carbon/epoxy laminates

Aluminium alloys for advanced structural applications in transport aircraft

This paper concisely reviews and discusses (1) metallurgically cleaner alloys like -2124, 2048 and 7475, (2) potential application of 7000 series alloys in tension panels, (3) development of high strength stress corrosion resistant thick section materials like 7010, 7049 and 705O, (4) powder metallurgy 7000 series alloys with high strength and...

The requirement of damage tolerance: An analysis of damage tolerance requirements with specific reference to MIL-A-83444

Fail-safety or damage tolerance i s generally considered as a highly desirable and in some countries as anobligatory property of transport aircraft structures. Recently the USAP issued a detailed requirement on damage tolerance. In the present report various aspects of damage tolerance are discussed with specific reference to the USAP...

Residual strength data of riveted panels with different stiffener configurations

Residual strength tests were carried out on center-cracked panels with a 2024-T3 or 7075-T6 skin and provided with eccentric stiffeners of practical design. The stiffeners were riveted to the skin. The material of the stiffeners was 7075-T6. In some cases the stiffeners were combined with Ti-alloy crack stoppers. On the basis of the test results...

User's manual of ARREST, a computer routine for prediction of residual strength of cracked stiffened panels

This report gives a detailed description of the computer program ARREST and of the execution of it in determining the residual strength diagram of cracked stiffened panels. The essentials of the computer program are dealt with in chapters 1 through 5, whereas the derivation of the equations together with the program flow charts ajid the program...

Calculation of vibration modes and resonance frequencies of the Northrop NF-5

The component mode technique is used to calculate resonance frequencies and vibration modes of the Northrop NF-5 structure. The results of the calculations are compared with those of a ground vibration test.