- TITLE:
EFFECTIVENESS OF DIFFERENT METHODS FOR FATIGUE LIFE ENHANCEMENT OF FASTENER HOLES IN D16AT ALUMINUM ALLOY
- AUTHOR(S):
G. V. Duncheva, J. T. Maximov, N. Ganev, A. P. Anchev
- ABSTRACT:
An evaluation of the effectiveness of three different methods for enhancement of fatigue life of
fastener holes in D16AT aircraft Al-alloy has been made. Objects of comparative analysis are the
friction stir hole expansion (FSHE), solid mandrel cold working and symmetric cold expansion
(SCE) methods. The results are generalized on the basis of fatigue tests, S-N curves obtained, X-ray
diffraction and micro-structural analyses. Under the high-cycle fatigue performance, the SCE
provides more than 66 times longer fatigue life as compared to solid mandrel method and more than
82 times greater fatigue life in comparison with FSHE method. Through X-ray diffraction analysis it
has been found out that the higher efficiency of the SCE method is due to the symmetric distribution
(with respect to the plate middle plane) of the introduced residual hoop stresses around the hole. On
the other hand, the solid mandrel cold working method causes a significant gradient of the residual
stress distribution in the thickness plate direction, which is a precondition for nucleation and
propagation of corner fatigue cracks. It has been established that the FSHE method efficiency
depends primarily on the heat generated and the equivalent plastic strain size. The combination of
these factors determines the beneficial micro-effect of the microstructure modifying immediately
around the hole and the useful macro-effect due to the introduced compressive residual stresses. It
has been concluded that SCE method should be used for pre-stressing of fastener holes in the most
loaded components in the D16AT aircraft structures - wings and fuselage, while FSHE method can
be applied for processing of fastener holes in less loaded aircraft components.
- DOWNLOAD:
EFFECTIVENESS OF DIFFERENT METHODS FOR FATIGUE LIFE ENHANCEMENT OF FASTENER HOLES IN D16AT ALUMINUM ALLOY
- TITLE:
COMMUNICATION SYSTEM FOR STRAIN ANALYSIS OVER METALS ON THE BASE OF TENSORESISTOR TRANSDUCERS
- AUTHOR(S):
Stanimir Sadinov, Dionisia Daskalaki, Panagiotis Kogias, Michail Malamatoudis
- ABSTRACT:
In this paper an architecture of a system for strain investigation and analysis over metals with
remote access is proposed. The deformations of the test turners are measured by two strain gauges
connected to adjacent arms of a Winston bridge. Using the data about the change of the output
voltage in the measurement diagonal (Uout) of the bridge, transmitted over the LabVIEW configured
serial communication channel, from NI USB 6002 module an analytical models for applied force
prediction (F) were obtained by STATISTICA software. The models are examined with a high
coefficient of determination R2 above level 0.98. The results according to synthesizing artificial
neural networks in MATLAB environment about determination the amount of measuring transducers
in detection the loads of experimental cantilever beam are presented. Two neural models with 9 and
6 hidden neurons about variables “Uout” and combination “F and Uout” with correct classification
of test data were selected. Levels of the mean square error related to the synthesized neural network
in two 9.9631e-04 compared to the network in one input parameter 0.0832 are observed,
respectively.
- PAGES:
97-
- DOWNLOAD:
COMMUNICATION SYSTEM FOR STRAIN ANALYSIS OVER METALS ON THE BASE OF TENSORESISTOR TRANSDUCERS
- TITLE:
OBTAINING OSCILLATORY SYNCHRONIZATION BETWEEN TWO VAN DER POL CHAOTIC SYSTEMS
- AUTHOR(S):
Dragomir Chantov, Hristina Stoycheva
- ABSTRACT:
The subject of this paper is from the field of nonlinear control theory and in particular from the
theory of chaotic systems and their synchronization. A novel synchronization scheme between two
Van der Pol chaotic systems is proposed by which the two systems become synchronized in a more
complex way than the usual one with the identical synchronization. The error functions between the
systems’ variables are not zero after synchronization is achieved nor fixed constants but periodic
functions. This is achieved by a novel approach to define the control functions. The oscillatory
chaotic synchronization can have some advantages in the chaotic communication systems regarding
the degree of protection of the information signal.
- PAGES:
92-
- DOWNLOAD:
OBTAINING OSCILLATORY SYNCHRONIZATION BETWEEN TWO VAN DER POL CHAOTIC SYSTEMS
- TITLE:
DC LINK CURRENT IN SINGLE PHASE H-BRIDGE INVERTERS
- AUTHOR(S):
Wensong Shen, Folker Renken, Adriana Foanene, Josef Timmerberg
- ABSTRACT:
The dc-link current in pulsed power inverters has in addition to the dc-value a substantially ac-
component. This current heads up the dc-link capacitors and must be considered for the inverter
dimensioning. Because these capacitors have a major impact on the volume, weight and costs of
inverters the current must be exactly determinates. In this paper the rms-current in the dc-link
capacitor is calculated depending on the phase output current amplitude, phase shift angle and
inverter modulation factor. The calculations are verified by practical measurements.
- PAGES:
88-
- DOWNLOAD:
DC LINK CURRENT IN SINGLE PHASE H-BRIDGE INVERTERS
- TITLE:
SIMULATION STUDY OF STATIC MAGNETOELECTRIC CHARACTERISTICS OF A DUAL-COLLECTOR MAGNETOTRANSISTOR
- AUTHOR(S):
Anatolii Aleksandrov, Kazolis Dimitrios Theodosius, Goran Goranov, Gergana Mironova
- ABSTRACT:
A simulation approach is applied to study the static magnetoelectric characteristics of a dual-
collector bipolar lateral magnetotransistor. A simulation setting is proposed for obtaining the
characteristics in PSpice based environments using an analog-behavioral model of the
magnetotransistor. Static magnetoelectric characteristics were obtained for a sample of a dual-
collector magnetotransistor 2T1MP1 connected in a common emitter circuit. Analysis and evaluation
of the results was carried out.
- PAGES:
83-
- DOWNLOAD:
SIMULATION STUDY OF STATIC MAGNETOELECTRIC CHARACTERISTICS OF A DUAL-COLLECTOR MAGNETOTRANSISTOR
