In-Situ Sensing of the Expansion of Low Density Core (LDC) Ti-6Al-4V Sandwich Structures

1998 ◽  
Vol 521 ◽  
Author(s):  
D. T. Queheillalt ◽  
B. W. Choi ◽  
H. N. G. Wadley ◽  
D. S. Schwartz
Keyword(s):  
Relative Density ◽  
Eddy Current ◽  
Elastic Moduli ◽  
Sandwich Structures ◽  
Ultrasonic Sensor ◽  
Low Density ◽  
Laser Ultrasonic ◽  
Simple Method ◽  
Aerospace Applications ◽  
In Situ Sensing

ABSTRACTA combination multifrequency eddy current and laser ultrasonic sensors have been used to measure the pore expansion kinetics and elastic moduli evolution during the annealing of low density core (LDC) Ti-6Al-4V sandwich structures. The LDC samples were heated to 920°C and held there for up to 12 hr. The eddy current sensor measured the sample thickness (i.e. relative density) and revealed that the samples began to expand early during heating and was nearly complete after 4 hr at 920°C. The laser ultrasonic sensor measurements indicated a concomitant decrease in the elastic moduli with the reduction in relative density. The combination of an eddy current and laser ultrasonic sensor is therefore able to measure both the density and the elastic moduli independently during the annealing stage of LDC Ti-6Al-4V sandwich structure processing providing a simple method for directly controlling the parameters most critical to aerospace applications of these new materials.

ALCOA ALLOY 2090-T83

Alloy Digest ◽  
2000 ◽  
Vol 49 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Density ◽  
Sheet Alloy ◽  
Aerospace Applications ◽  
Aluminum Lithium

Abstract Alcoa alloy 2090-T83 is an aluminum-lithium sheet alloy with a combination of strength, low density, and corrosion resistance. The alloy is used in aerospace applications. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as joining. Filing Code: AL-371. Producer or source: Alcoa Mill Products Inc.

scholarly journals Laser ultrasonic assessment of the effects of porosity and microcracking on the elastic moduli of nuclear graphites

2016 ◽  
Vol 471 ◽  
pp. 80-91 ◽  
Author(s):  
James B. Spicer ◽  
Lauren R. Olasov ◽  
Fan W. Zeng ◽  
Karen Han ◽  
Nidia C. Gallego ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Laser Ultrasonic ◽  
Ultrasonic Assessment

Large-Scale Laser Ultrasonic Facility for Aerospace Applications

1999 ◽  
pp. 387-393 ◽  
Author(s):  
Kenneth R. Yawn ◽  
Thomas E. Drake ◽  
Mark A. Osterkamp ◽  
S. Y. Chuang ◽  
Paul Acres ◽  
...  
Keyword(s):  
Large Scale ◽  
Laser Ultrasonic ◽  
Aerospace Applications

scholarly journals Multi-objective design optimization of a permanent magnet axial flux eddy current brake

2019 ◽  
pp. 998-1011
Author(s):  
RASUL TARVIRDILU ASL ◽  
HÜSEYİN MURAT YÜKSEL ◽  
OZAN KEYSAN
Keyword(s):  
Eddy Current ◽  
Effect Of Temperature ◽  
Test Results ◽  
Algorithm Optimization ◽  
Axial Flux ◽  
Multiobjective Genetic Algorithm ◽  
Aerospace Applications ◽  
Eddy Current Damper ◽  
Brake Performance ◽  
Speed Characteristic

The main aim of this study is to optimize an axial flux eddy current damper to be used in a specific aviation application. Eddy current dampers are more advantageous compared to conventional mechanical dampers as they are maintenance-free due to contactless structure and have higher reliability, which is very desirable in aerospace applications. An initial eddy current brake prototype is manufactured and the test results are used to verify the 3-D finite element simulations. The effect of temperature on the brake performance is investigated. Finally, a multiobjective genetic algorithm optimization is applied to find the optimum pole number and geometric dimensions of the eddy current brake in order to achieve the desired torque-speed characteristic while the total weight of the brake is minimized. It is found that the mass and volume of the initial prototype can be halved by implementing this optimization algorithm.

Capability of non-destructive techniques in evaluating damage to composite sandwich structures

2019 ◽  
Vol 10 (3) ◽  
pp. 356-370 ◽  
Author(s):  
Petr Bělský ◽  
Martin Kadlec
Keyword(s):  
Service Use ◽  
Sandwich Structures ◽  
Impact Damage ◽  
Lower Sensitivity ◽  
Destructive Testing ◽  
Content Type ◽  
Aerospace Applications ◽  
Number Of Factors ◽  
The Many ◽  
Non Destructive

Purpose Defects can be caused by a number of factors, such as maintenance damage, ground handling and foreign objects thrown up from runways during an in-service use of composite aerospace structures. Sandwich structures are capable of absorbing large amounts of energy under impact loads, resulting in high structural crashworthiness. This situation is one of the many reasons why sandwich structures are extensively used in many aerospace applications nowadays. Their non-destructive inspection is often more complex. Hence, the choice of a suitable non-destructive testing (NDT) method can play a key role in successful damage detection. The paper aims to discuss these issues. Design/methodology/approach A comparison of detection capabilities of selected C-scan NDT methods applicable for inspections of sandwich structures was performed using water-squirt, air-coupled and pitch-catch (PC) ultrasonic techniques, supplemented by laser shearography (LS). Findings Test results showed that the water-squirt and PC techniques are the most suitable methods for core damage evaluation. Meanwhile, the air-coupled method showed lower sensitivity for the detection of several artificial defects and impact damage in honeycomb sandwiches when unfocussed transducers were used. LS can detect most of the defects in the panels, but it has lower sensitivity and resolution for honeycomb core-type sandwiches. Originality/value This study quantitatively compared the damage size indication capabilities of sandwich structures by using various NDT techniques. Results of the realised tests can be used for successful selection of a suitable NDT method. Combinations of the presented methods revealed most defects.

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