DETERMINING THE TRUE LOADING DIAGRAM BY THE DISPLACEMENT FIELD IN THE SAMPLE NECK

The article presents a technique for determining the true loading diagram of a material along the displacement field. The technique is based on the assumptions about the coincidence of the initial sections of the true and experimental loading diagrams, the coincidence of the experimental and calculated maximum loads, and the coincidence of the calculated and experimental displacement fields in the sample neck after tensile testing. The required test results of wire samples (steel SV-07X16N6) and the expression in the form of the formula for the displacement field were used published in the literature. Young's modulus, Poisson's ratio and plastic curve were determined by the method proposed in the work. Modeling was carried out in the Abaqus software package according to a model based on the hypothesis of a single loading curve and homogeneous and isotropic hardening. The correctness of certain elastic-plastic properties of the material was determined by the coincidence of the calculated and measured loading diagrams, the maximum values of the calculated and experimental load and the experimental and calculated displacement fields, as well as the assessment of the load range at which the sample was divided into parts, and the calculated values of the separation load data range. In the process of applying the methodology, the satisfaction of all formulated requirements was achieved. It is shown that the true loading diagram has a yield area, as well as a section of an intense (convex downward) section of hardening after it. The results obtained will be useful in modeling units and assemblies, as well as technological processes in which the material is plastically deformed and an increased accuracy of calculating changes in their geometric shape is required. The work also contains all the results of determining the elastic-plastic properties of the material in a tabular form, necessary for the use by specialists, for use in their professional activities.

On the Identification of a Loading Scheme in Large Radius Air Bending

Large radius air bending has a different loading diagram than conventional bending, which affects the material behavior during the bending process. In order to establish a correct loading diagram, the position of the contact points between the plate and the punch is determinant. The position of the contact points is depending on the evolution of the bending process and the influence of the material is unknown. In this work, the determination of the position of the contact points in large radius air bending has been studied by means of both an experimental campaign and finite element analysis. Experiments were performed on a press-brake with a capacity of 50 metric tons. High-strength steel Weldox 1300 and aluminum alloy AlMg3, and punches of radii 30, 35 and 40 mm have been used. During the bending process, the punch movement has been monitored and the bending angle has been measured by means of images recorded by a camera system. Based on the obtained results, the relation between the bending angle and the position of the contact points is discussed.

Static Testing of Draft Sensor for Three Point Hitch Dynamometer Utilization

This paper investigates the possibilities in design of universal three point hitch dynamometer. Approaches in different hitch dynamometers are explained and pros and cons are mentioned. Also main parts and functional principle of draft sensor are clarified. The main goal of this research is clarification and examination of draft sensor output signal on angular draft force dependences. Utilization of draft sensor as a source for draft force sensing in lower arms is intended and examined. Research was focused on loading of draft sensor in different directions for proper screening of voltage output. Special loading device was designed and used with respect of real mounting conditions and force loading identically to bearing pins of tractor hitch lower arms. With usage of calibrated load cell and National instrument sensing control unit stage loading diagram of draft sensor was obtained. Results show basic feedback of voltage output on force load angle variation. In non-load condition, voltage output fluctuates around 5 V. In the main direction of draft force application voltage drop occurs from 5 V up to 3.16 V. Reverse direction of loading brings the voltage output increment from 5 V up to 7.06 V. When the load is applied with angular inclination voltage output changes are diminished up to 90° and draft sensor shows voltage output symmetry against the main axis. Based on stage loading diagram the appropriateness of draft sensor usage in design of universal three point hitch dynamometer is discussed in paper summary. Also further research opportunities and results application are suggested.

A Simplified Stability Letter for Offshore Supply Vessels

This paper presents a simplified method for the preparation of stability information for offshore supply vessels. The paper reviews the current methods used by the Eighth Coast Guard District Merchant Marine Technical Office for preparation of stability information and compares these with the proposed "simplified" method. The simplified stability letter incorporates a loading diagram which will make it easier for the vessel operator to use. The recommended letter will allow designers to obtain a higher maximum amount of deck cargo, provide more flexibility in the manner in which cargoes are carried, allow operators to exchange consumables for additional below-deck cargo, and simplify the calculations necessary for preparation of the stability information. It should be cautioned that the method presented is only the opinion of the authors. Approval should be obtained from the cognizant Coast Guard technical office before employing this or any other proposed method. It should also be noted that the stability criteria presented in Appendix I are not yet included in regulations and are subject to change.