Zbigniew Lutowski

Usage of Digital Image Correlation in Analysis of Cracking Processes

Abstract In this paper, the analysis of the possibilities of using Digital Image Correlation (DIC) based on Graphics Processing Unit (GPU) for strain analysis in fatigue cracking processes is presented. The basic assumption for the discussed displacement and strain measurement method under time variable loads was obtaining high measurement sensitivity by simultaneously minimizing the measurement time consumption. For this purpose special computing procedures based on multiprocessor graphic cards were developed, which significantly reduced the total time of displacement and strain analysis. The developed digital procedure for correlation of images has been used for an example of displacement analysis in the method of fatigue crack propagation testing in airplane riveted joints. In this paper are presented the results of the researches of the team run by professor Antoni Zabłudowski

The Investigations of Fatigue Cracking of Laser Welded Joint with the Use of ‘FatigueVIEW’ System

In this paper, the possibilities of detection and measurement of fatigue crack length in welded joints made of steel of duplex type, have been presented. In the investigations there has been used an original research system FatigueVIEW employing advanced optoelectronic techniques and numerical methods of image analysis. The proposed approach enables analysis of the fatigue crack growth during fatigue tests and after their finishing in off-line mode.

Dual-Band Experimental System For Subsurface Cracks Testing

The authors of this article have presented a hybrid method for inspection in the visible and infrared bands. A model of a test stand equipped with a monochromatic CCD and thermovision cameras which enable execution of tests in the field of active and passive thermography has been presented. Application of two vision channels provides the possibility of observing the defects caused by cracks and non-uniformity of a material structure, in the subsurface layer. An analysis of experimental tests performed on selected objects has been presented. Images from both channels, effects of the image overlapping and profiled charts along characteristic lines in thermograms have been shown.

The Use of Texture Analysis in Optical Inspection of Manufacturing Processes

The paper presents a method of optical inspection of manufacturing processes in the visible band. The presented model of the test bench was based on a monochrome CCD camera that allows one to conduct research in the field of digital image analysis. The wavelet transform was proposed for the detection of objects. This wavelet transform allows examining pictures with use of textures. The article presents an analysis of the results of experiments for selected objects using the proposed method, allowing the evaluation of the correctness of classification. In the article, the advantages of using the proposed method in a sample manufacturing process to recognizing surface defects (e.g. cracks or scratches) is discussed.

Analysis of Strain Distribution in Notch Zone in Aluminium FSW Joints for Irregular Fatigue Loading Conditions

Joining aluminium alloys with the use of welding techniques often impairs their strength properties and in some cases it is very difficult or even impossible. An alternative method for joining this type of material is friction welding including FSW welding. The airplane aluminium alloy 2024-T3 is an example of material that can be welded using this method. Heat emitted during the process, which contributes to the material plasticisation in the zones of welding, causes significant changes in the material structure, thus affecting the joint properties. Fatigue life calculations of this type of joint can be performed according to different approaches. One of them is a local approach which requires knowledge of local strains or stresses within the notch zone. This paper is a presentation of exemplary results of experimental and numerical tests of strain in the zone of notch that occur in a joint under time variable loading.

Application of Digital Image Correlation in Fatigue Crack Analysis

In the paper method of displacement analysis in the cracking zone based on digital image correlation and advanced multi-processor graphic cards procedures was presented. The basic assumption for the discussed displacement and strain measurement method under time variable loads was obtaining high measurement sensitivity by simultaneously minimizing the measurement time consumption. The developed digital procedures for correlation of images has been used for an example of displacement analysis in the crack propagation testing in airplane riveted joints.

Control Algorithms in Multi-Agent Environment

Abstract In this paper the general information regarding controlling multi-agent systems has been given. The simulation results of using algorithms, proposed by authors, used for controlling groups of robots servicing the virtual library has been presented. These simulations concerned estimation of following parameters: number of iterations needed to complete a task, average customer service time and average customer awaiting service time in function of number of robots, size of library and number of exchange points.

Modeling Telecommunication Networks with the Use of Reference Graphs

In this paper, an algorithm for finding graphs with parameters of Reference Graphs was presented. During the Reference Graphs search, it was found that in most cases with a specific number of nodes and equal degrees of nodes, there is more than one graph with identical baseline parameters, the diameter and average path length, and the number of these graphs increases with the increase of the number of nodes and their degree. To clarify where these differences are occurring, it was decided to define the characteristics of the comparable structures that could affect the transmission properties.

Analysis of the Possibility of Emission Reduction for Complex WSN Networks by the Implementation of a Larger Number of Acquisition Nodes

Abstract The article presents the results of simulations conducted on the network which has been implemented in one of the cities with dense urban development. The simulations were conducted to verify how the lowering of the emission (this affected the topology of the network) of the network will affect the network reliability and time of the data collection.

Analysis of Possibilities to Limitate the WSN Network Emissivity at Assumed Probability of Correct Transmission

Abstract The article presents the results of considerations regarding assuring the assumed probability of obtaining a correct transmission while limiting the emissivity of the WSN network. The first part presents the method of selecting the location of the acquisition node and analyzes the impact of the increase in transmission levels on the probability of obtaining a correct transmission. The second part presents and analyzes the method of reduction of the network’s emissivity at the assumed level of correct data transmission, and the end contains a summary and conclusions from the presented considerations.