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This research focuses on cylindrical helical springs with circular cross-sections made from carbon steel (SH 0.82% C) and stainless steel (AISI 302). The transformation from a linear bar to a circular spiral involves numerous factors such as material mechanical behavior, stress–strain relationships and residual stresses. This research investigates the spring-back phenomenon, which affects the final diameter of helical springs post-manufacture, using analytical, experimental and numerical methods. An analytical model, derived from the mechanical bending process, was proposed to predict spring-back, and its accuracy was validated against experimental data. This study also employed finite element simulations to analyze elastic recovery, confirming the analytical predictions. Results indicated that the spring-back ratio k could be expressed as an exponential function of the spring index C (the ratio between the final diameter of the spring D2 and the diameter of the wire DW), with a maximum error of 4.80% for stainless steel and 3.62% for carbon steel. This study's findings provide valuable insights into optimizing the spring manufacturing process, enhancing the precision of spring diameter predictions, and potentially reducing production errors and material waste. [ABSTRACT FROM AUTHOR]

The present research describes a design of an overhead crane using different materials with a prestress method, which corresponds to an external compression force with the aim of reducing the displacement of the beam due to the external load. This study concerns a bridge crane with a span length of 10 m, with a payload equal to 20,000 N and an estimated fatigue life of 50,000 cycles. Three different materials are studied: steel S355JR, aluminium alloy 6061-T6 and carbon fibre-reinforced polymer (CFRP). These materials are analysed with and without the contribution of the prestress method. In reference to the prestressed steel solution (which has a weight equal to 79% of the non-prestressed configuration), this study designed an aluminium solution that is 50.7% of the weight of the steel one and a composite solution that is always 20.3% of the steel configuration. In combining the methods, i.e., the materials and prestress, compared to the non-prestressed steel solution with a weight evaluated to be 758 kg, the weight of the aluminium configuration is equal to 40% of the traditional one, and the composite value is reduced to 16%, with a weight of 121 kg. [ABSTRACT FROM AUTHOR]

The purpose of this numerical research is to study a derrick crane under repeated loads. The numerical analyses were carried out considering two different geometrical crane configurations, and two different rope lengths. After a preliminary analysis in order to evaluate both static and dynamic (modal) crane performance, many different analyses were carried out applying different load sequences. These actions were characterized by several impulse loads, which can be applied during the crane active use. Two parameters characterize the impulse load, i.e. the impulse duration and the delay between two successive actions. This load condition, which is not present in the crane design standards, was experimentally checked during the machine use in the marble quarry where it was installed. The results show that in specific crane configurations, characterized by the main arm position and the rope length and with a specific load sequences, both the vibration and the displacement magnitude increase in time, inducing high stress value in the crane components that can collapse the crane itself.

The aim of this research is to study the dynamic behaviour of a real gantry crane subjected to the actions induced by the trolley and payload movement. A specific numerical procedure was developed and implemented in the finite element method in order to simulate different trolley movement modes on the crane's main beam. From the results, it is clear that the crane displacement, especially the longitudinal one, is strongly dependent on the acceleration both in the starting phase and in the stopping phase to which the trolley is subjected during its movement on the crane main beam. The last part of this research simulates the sudden stop of the trolley movement and subsequent payload swinging; in this case, the length of the rope that suspend the payload to the trolley has a fundamental role in the trend and maximum longitudinal crane displacement value.

The upgrade of the scintillating bars detector, used in the experiments of the ASACUSA Collaboration at the CERN Antiproton Decelerator is presented. The detector consists of several modules, each one made of ≈1m long scintillating bars, which allow the detection of the charged particles produced in the annihilations of antiprotons and antihydrogens. The mechanics, the electronic readout and the data acquisition system upgrade are described.

This paper describes the research on the mechanical behavior of a container crane subjected to variable wind loading. In the first step the wind action was studied and defined. Stochastic wind loading was simulated by means of power spectrum method. Preliminary analyses were carried out on a chimney (100 m) because its geometry is very simple. Many different schematizations were implemented both to evaluate the results convergence and to define the correct finite element method schematization. At the end, the results were compared with those obtained by classical methodology, i.e. by response to an equivalent force which was evaluated by multiply the wind pressure with the front area and defined coefficients. The next step was to design the crane (pay load =50 t) and to study the mechanical response of the structure to the dynamic wind actions defined in the previous step. The results (displacement) of numerical analyses show that the classical method used to study the wind actions applied on the structures overestimates those determined by power spectrum method.

The target of this numerical study is to investigate the problems involved in the design of a low profile container crane exposed both to static and dynamic wind actions, in order to establish if these loads are dangerous when compared with the load induced by standard container load and unload operations. In the first step the work was performed by means of different schematizations of the wind load action allowed by the standards; the second step regarded the application of a real trend (velocity of wind versus time) obtained experimentally on a similar crane positioned in an Italian harbor. The results obtained in terms of maximum displacement depend on the crane load conditions and on the different schematizations used for the wind action. Using a variable wind pressure, the research shows that the effects of wind loads are greatly influenced by the natural vibration frequencies of both the structure and the elements that compose the structure.