The article introduces a simple and efficient higher-order explicit numerical scheme for the integration of a system of ordinary differential equations which is constrained by an algebraic condition (DAEs). The scheme is based on the truncated Taylor series expansion of the constraint equation, with order h of the scheme being determined by the highest exponent in the truncated Taylor series. In conjunction with a direct solution technique used to solve the boundary value problem, the NICEh scheme is very convenient for the integration of constitutive models in plasticity. The plasticity models are defined mostly by a system of algebraic and differential equations in which the yield criterion represents the constraint condition. To study the properties of the new integration scheme, which, like the forward-Euler scheme, is characterized by its implementation simplicity in FEM due to the explicitness of its formulations, a damage Gurson-Tvergaard-Needleman constitutive model is considered. In the studied cases the accuracy of the higher-order explicit scheme is significantly higher than the accuracy of the classical backward-Euler scheme, if we compare them under the condition of a similar CPU time consumption.
COBISS.SI-ID: 11946779
A fully coupled, partitioned, numerical model that accounts for fluid-structure interaction is applied for a study of installation effects in a straight-tube Coriolis flowmeter. Three flow disturbance elements positioned at different locations upstream of the measuring tube are considered in the study: a single elbow, closely coupled double elbows out-of-plane, and an orifice. The installation effects are estimated by comparing the mass-flow sensitivities obtained for the disturbed and the fully developed flow conditions in the measuring tube. The interpretation of the installation effects is given by analysing the anti-symmetric fluid forces in the measuring tube. The simulation results show that the magnitude of the installation effect in asymmetrically distorted flows varies for the different circumferential positions of the motion sensors. The sensitivity variations around the circumference of the measuring tube are less pronounced for measuring tubes with a higher circumferential stiffness.The predicted installation effects are also affected by changing the vibration direction of the tube with respect to the disturbance elements.
COBISS.SI-ID: 13171739
The main benefit in using optimally shaped blanks in sheet metal forming is in maximizing the efficiency of the forming process and, since there is no need for additional cutting operations after the finished forming operation, in substantial reduction of the overall production cost. The paper presents a numerical method for optimal blank shape determination which is suitable in various sheet metal forming applications. The optimal blank shape is determined in iterative way so that the edge geometry of the formed product fits its reference geometry as close as possible. The iterative process starts at blank shape from which the product is produced with its edge fitting its reference geometry just approximately. In subsequent iterations the blank shape is continuously improved in accordance with the developed optimisation method. In order to determine the product edge geometry resulting from the current blank shape, a computer simulation of the forming process and the springback is performed in each iteration. Since its effectiveness highly depends on the quality and physical objectivity of the computer simulation, the developed numerical blank shape optimisation procedure has been validated also experimentally by considering forming of a product with rather complex edge geometry as the case study.
COBISS.SI-ID: 12737819