Papers by Keyword: Failure

Abstract: The European Standard [1] for design of concrete compressed slender members shows a significant deficit in global reliability for the design method based on non-linear analysis. The experimental investigation at the Faculty of Civil Engineering SUT in Bratislava was planned for slender concrete columns made of different concrete strength classes - C45/55, C70/85 and C100/115. A basic aim of the analysis was to design concrete columns subjected to bending moment and axial force where the stability failure proceeds at the compression strain 1.5 ‰. The first of three series of experimental and numerical analyzed columns is presented in the paper. The experiments were realized at the Faculty of Civil Engineering SUT in Bratislava with cooperation of ZIPP Bratislava LTD Company.

Abstract: The paper deals with the response analysis of interaction of a gaseous shock wave and a glass plate structure with particular reference to the character of excitation wave and material characteristics of structure. The goal of this analysis is the determination of a hypothesis of failure of window glass plate on the basis of the actual plate rotation during extreme plate displacement. Pressures greater than the ultimate stress or plate rotation bring to the collapse of the glass plate structure. The assumptions and results of theoretical - numerical solution are compared with experiments in situ and in laboratory conditions.

Abstract: Literature reported extensive work on the failure of Industrial power transmission systems, during their routine torque transmission, rotary motion etc. During transmission through gear drive the noise, temperature, stresses, vibration etc are important factors to be considered. When one or more of above exceed certain design limits, the drive and its accessories must be examined for the cause and a preventive maintenance is to be followed. The latest research work carried out, in above area is reviewed. The cause of failure and failure analysis is examined. An attempt is made in this paper, to systematically analyze the modes of failures, the reasons for the same, issues and challenges involved, there in, and measures to be taken for addressing them. This analysis is likely to help the researchers to proceed further in analyzing the failure and to suggest means to prevent failure of gear power transmission systems. The major contribution of present work is, to present the common modes of failure of gear teeth in power transmission systems, and measures to be taken to address the same. In general various additives in the lubricating oil help in controlling initiation of pitting. The present work involves controlling one of the additives namely sulphur in the lubricating oil to control pitting. The present work forms an excellent basis for identifying various other parameters affecting the pitting failure of gear teeth in a gear box.

Abstract: Concrete patch repair is becoming an important facet of the civil construction industry when considering the large quantity of exposed concrete surfaces requiring maintenance and rehabilitation during its design life cycle. Patch repairs are more often than not done with a specialized polymer-modified mortar which requires adequate quality control and quality assurance during application and curing to ensure long-term success. Unfortunately, there have been many patch repair projects where there has been poor performance of the patch repairs resulting in debonding, cracking and discolouration. In this paper, poor or inadequate quality control during the patch repair process is investigated as one of the possible reasons for poor performance and premature failure . It is postulated that because of the lack of adequate knowledge and understanding of the repair material and the repair process by the various stakeholders (applicator, supplier, consultant and client), deficiencies in the quality control and quality assurance before, during and after the repair project often exists. In many patch repair projects, the responsibility for the successful completion of the patch repair work and the assessment of long term performance of patch repairs is not fully embraced by all of the parties involved.This postulation has led to the research, by using questionnaires designed specifically for the four different stakeholder categories of the concrete repair industry. The results indicate that there is very little discussion amongst the stakeholders regarding quality control and acceptance criteria when performing concrete patch repairs, neither for the identification of patch repair failure directly after the completion of the patch repair, nor for long term performance of the patch repairs.

Abstract: The paper presents Six-Sigma methodologies, which is powerful method for increasing quality and development of manufacturing, by understanding risk factors, can suggest proper and thoughtful decision-making that may protect the business plan from causes. This study examines a framework of improved performance under the possible influence of different failure modes. Econometric verification presents statistical assumptions for the application of estimated procedures in the area of logistics, especially in the area of industrial logistics. The statistical method for the methodology is to test statistical reliability and the significance of estimated parameters for the analysis of numerical values of risk priority.

Abstract: Numerical models describing crack formation and growth in reinforced concrete give reasonably good estimates of the bearing capacity and durability of an element of the structure without expensive full-scale tests. In this paper, a finite-element model is proposed to study the failure of a rectangular reinforced concrete beam subjected to four-point bending. The results of quasi-static simulation and the data obtained by taking into account inertial forces are compared. The feasibility of taking into account inertial forces is justified by assessing the contribution from kinetic energy (above 30%) at the instant of crack formation to the total mechanical energy of the system. Comparison of the experimentally obtained and calculated crack patterns is performed. It is shown that the mechanism of debonding between the reinforcement and concrete plays a key role in cracking.

Abstract: The strength and tightness of flange joints will be weaker due to the temperature fluctuations. There exists no mature calculation procedure that can accounts for the temperature fluctuations’ effect on the performance of flanged joint. Based on the finite element simulation of a flanged joint under emergency stop and drive condition using ANSYS, the strength integrity and sealing performance of it are evaluated according to code JB4732-2005. The results show that stress of every component increases after experiencing an emergency stop and drive, flange deflection is more serious, resulting in integrity and tightness failure and can’t meet the sealing requirements. Repeatedly stop and drive will lead to discontinuity and alternating loads for the flanged joints, which will increase the leakage trend.

Abstract: One of the basic means of improving the reliability of technical equipment is increasing their reliability through targeted maintenance. When designing any technical equipment should be chosen minimum necessary set of technical resources that are necessary to the achievement of the required scope and quality of its functions. By setting an appropriate preventive maintenance plan can be timely and effective interventions to prevent adverse consequences of failure. This paper describes the proposal of optimal plan of preventive maintenance of experimental equipment designed for 3D machining rotating parts with AWJ technology.

Abstract: This paper focuses on progressive damage investigation and failure analysis of carbon fiber reinforced laminates under varying strain rates in tensile mode. Samples specimen prepared for experiments were made from unidirectional ply with 70/30 fiber-matrix volume fraction and cross-ply (0°-90°) balanced stacking. These laminates were subjected to uniaxial longitudinal tensile loading in a Universal Testing Machine (UTM) with varying strain rates. Results acquired from the experiments were used to plot stress versus strain curves for different strain rates. These plots were subsequently analyzed to investigate the effect of varying loading rates on the mechanical properties and failure behavior of these composites. Experimental data revealed a considerable increase in the tensile strength with increasing strain rate. The tensile modulus and strain to failure were also found to exhibit slight increase with the increasing strain rate.

Abstract: In this paper, the dynamic deformation and rupture of pre-notched thin metal plates subjected to confined blast loading were investigated. The thin copper plates with cross-shape pre-notch were clamped on the end of a confined cylinder vessel by a cover flange. An explosive charge with a mass of 4g was detonated in the vessel center to generate blast load acting on the metal plates. The images of metal plates were recorded by two high-speed cameras. The displacement and strain fields during the deformation and rupture process were measured by using 3D digital image correlation (3D DIC). The effects of pre-notches on the dynamic deformation and rupture of thin metal plates were analyzed. The microstructure of fracture surface was examined The 3D DIC technique is proven to be an effective method to conduct dynamic full-field deformation measurement.