This article includes several studies and advanced research carried out on the subject of large KANGUR-type port cranes, subjected to regular or interventional maintenance work; besides the beneficial effects for which they were intended, some undesirable effects were detected in terms of affecting safety in exploitation. The purpose of this paper is to identify the risk factors and to offer sustainable solutions for increasing operational safety and service life for the respective equipment, as well as for other similar fields of activity, including oversized structures. Following the theoretical studies and the experimental research carried out in situ that confirmed the validity of the theoretical models used, the article in conclusion provides specific and sustainable solutions as well as new methods of assessment, which combine the positive elements of the usual solutions, but in parallel, allow the elimination of the negative side effects that may occur in time. Hence, the article’s novelties also consist of a new approach to achieve structural interventions, resulting in the increase in the service life, and in parallel with that, the safety in operation of the respective equipment.
This paper introduces a new method for the use of tensor-resistive sensors in large spherical storage tank equipment (over 12,000-mm diameters). We did an experiment with 19 petroleum or ammonia product sphere-shaped storage tanks with volumes of 1000 and 1800 cubic meters, respectively. The existing literature only contains experiments based on sensors for tanks with diameters no larger than 600 mm. Based on a number of resistive strain sensor measurements on large spherical pressurized vessels regarding structural integrity assessment, the present paper is focused on the comparison between "real-life" obtained sensor data versus finite element method (FEM) simulation results. The present paper is structured in three parts and examines innovative directions: the use of the classic tensor-resistive sensors in a new approach concerning large structural equipment; an original 3D modeling method with the help of the FEM; and conclusions with possible implications on the regulations, design, or maintenance as a result of the attempt of mutual validation of the new methods previously mentioned.
Hydraulic cylinders represent the main actuating/positioning element for standalone lifting equipment or equipment for various transport platforms. This type of actuator represents a structural component responsible for the operational safety of the equipment it serves. One of the most common and dangerous reasons concerning the end of life for this equipment is the buckling or loss of stability of the elastic equilibrium shape. This article aims to compare the classical approach of the problem in accordance with the strength of materials theory in relation to the numeric algorithms used in the applications for the analysis of structure behavior and the algorithms that are based on the finite element method. The subject of study is a hydraulic cylinder that is installed in a self-lifting platform and because of the manifestation of the phenomenon under analysis, it has led to a technical accident. For this purpose, an estimation of the value for the buckling critical load of the cylinder assembly was carried out.
1 July 2018 in Romanian Journal of Transport Infrastructure
The safety of railways has been and remains a critical topic. Whether it is infrastructure or rolling stock, the issue of safety is a permanent concern of the utmost importance, being reflected in the efficiency of any transport system. This paper focuses on the safety in operation of pressure vessels that equip railway tanks. There are many articles and works on this subject, and it is well-known that there are both national and international regulations regarding their design, execution, operation and maintenance. Also, there are quite a few reports on the BLEVE (Boiling Liquid Expanding Vapour Explosion) phenomenon resulting in material damage and significant casualties. The BLEVE-type explosion is not considered a chemical explosion derived from a gas-air explosive environment (also present in non-flammable gases), but rather a mechanical explosion through over-pressurization. Thus, we propose a comparative study between the results obtained using theoretical methods and those obtained as a result of tensoresistive measurements on such a tanker.
This article intends to define a new methodology that allows the processing of complex surfaces in space through processing cycles, in parallel superposed planes—the variant known as generic processing in 2 ½ D—but with predictable control over the deviation from the geometric form of the surface to be processed. The novel methodology consists of identifying the optimal distances between the working planes and the corresponding successive positions so that the deviations from the resulting geometric form fall within the prescribed limits. It is also envisaged that the method will provide facilities in terms of the possibilities for evaluation of deviations from the given form of the surface, and keeping them under control by the stage of elaboration of the numerical control programs. The new optimization is designed to determine the maximum distances between successive processing planes and their position in space, depending on the spatial shape of the surface to be processed. Thus, the aim is to obtain a small number of processing planes with a favorable effect on productivity, but under conditions that respect the tolerances of the surface or the profile, a restriction that otherwise has a negative effect on the same process.
30 September 2019 in CBU International Conference Proceedings
This article points out the problems resulting from the calculation of flatness deviations against the adjacent surface defined according to SR EN 1101-2017 and proposes the use of a larger number of measurement points for improved accuracy, along with the identification of a reference plane surface with the help of matrix calculations. All deviations should be re-calculated by comparison to this reference plane. In order to reduce the large number of errors resulting from many rounding applied, this paper proposes the method of deviation measurement at symmetrical coordinates, while the calculation of the reference plane surface would be made with the help of an original method, whereby the number of operations is reduced to a minimum in order to increase accuracy.