Papers by Keyword: Numerical Modelling

Abstract: In today’s competitive manufacturing landscape, balancing cost and performance is crucial. Additive Manufacturing (AM) offers a path to efficient, functional designs, with Four-Dimensional (4D) printing emerging as a key innovation. By using materials that are responsive to external stimuli, 4D printing enables objects to change shape over time, making them active and opening new possibilities in adaptive design. Building on this, research into the shape morphing behaviour of 4D-printed objects was conducted through simulation. Based on the literature, this process can be effectively approached as a thermomechanical problem. This work first simulates the shape morphing of two-layer structures. Multiple parameters are varied through Finite Element Analysis (FEA) to assess both their independent influence and the feasibility of the proposed method. The study then analysed the use of orthotropic properties to evaluate control over deformation directions. Finally, insights from these phases were applied to more complex geometries. It is concluded that the morphing process can be computationally planned using a thermomechanical approximation, paving the way for the incorporation of the influence of printing parameters, pattern design and the strategic division into active/passive regions. This study provides foundational work in 4D printing regarding the shape prediction of printed objects.

Abstract: Unmanned aerial vehicles (UAVs) are considered one of the modern technologies that have recently used in many military and civilian applications. This research investigates the aerodynamic stability of the STU.1.M predator drone was studied by studying the change in the values of the lift and drag coefficients and the lift-to-drag ratio using numerical modelling, Computational Fluid Dynamics (CFD) was employed to simulate performance across range of angles of attack (0° to 14°) at various speeds (20, 40, 60, 80 m/sec) under incompressible flow conditions. The engineering model of the aircraft was generated and the numerical validity was confirmed against experimental data from referenced study. The results indicated that the change in the value of the lift and drag coefficients and the lift-to-drag ratio with respect to UAV velocity is with no significant. The results also showed that the value of the lift coefficient and the lift-to-drag ratio increased with the increase in the value of the angle of attack, The maximum L/D ratio of 8.5 was achieved at a 6° angle of attack and speed of UAV 80 m/s, pressure and velocity contours identified stagnation regions with maximum pressure points at the UAV 's nose, wing, and tail.

Abstract: A mathematical model of the shaping processes of structurally inhomogeneous porous materials has been developed. Generalized relations of the theory of elastic-visco-plasticity for dispersed materials are used for rigid-plastic and elastic-plastic of the material solid phase models. The procedures of projection-grid methods for solving boundary value problems were used. It has been performed in form of step by step calculation. The special algorithm is used to consider some types of plastic deformation, including rigid plastic behaviour, elastic – plastic case and some other rheological behaviour of matrix materials. The algorithm procedures were realized in a form of numerical model. Some elements of this model were implemented in modern finite element software versions. The results of calculations, aimed at manufacturing of main and responsible parts are presented in article.

Abstract: This paper presents findings from an ongoing study on the condition assessment and numerical modelling of a reinforced concrete bridge B0140 along C46 in Ongwediva, Namibia. An analysis of bending moments, stresses and deflections of the bridge under the prevailing abnormal loads on the bridge was undertaken using Autodesk Robot Structural Analysis Professional (RSAP) software. The aim of this study was to develop a numerical model of bridge B0140. The objectives of this study were twofold, namely, to use the developed model to predict bending moments, stresses and deflection of the bridge structural elements and to evaluate the adequacy of the existing reinforcement under the prevailing environmental conditions and abnormal loads according to BS 5400 requirements. Information pertaining to the geometry of the bridge and the mechanical properties of the materials used for construction were obtained from “as-built” engineering drawings from the Roads Authority (RA) of Namibia, physical measurements and non-destructive testing in situ. Preliminary results from the developed model indicate that the bending moments, stresses and deflections of the bridge under the prevailing environmental conditions and abnormal loads are satisfactory. The developed model, however, needs further refinement, calibration and validation to improve its accuracy.

Abstract: ABAQUS is a powerful software for simulating nonlinear material models with complex thermo-mechanical behavior. Its robust capabilities make it particularly suitable for simulating the Rotary Friction Welding (RFW) process. In this study, ABAQUS was utilized to simulate the RFW process of AA6061 aluminum alloy, focusing on key aspects such as weld morphology, temperature distribution, and axial shortening. The simulation results were analyzed and validated against theoretical foundations of the RFW process and previous research, demonstrating the model's high reliability. These findings highlight the potential for further development of the simulation model for various applications, aimed at enhancing the efficiency and effectiveness of RFW in industrial applications.

Abstract: Reinforced concrete (RC) is a widely preferred material for all types of infrastructure. A few of the main advantages of RC are its durability and economical availability but at the same time its non-homogenous behavior makes it difficult to analyze especially in the cases where non-linear behavior of the structure is to be accessed. This paper presents a simplified numerical model tailored for the nonlinear analysis of reinforced concrete structures, emphasizing enhanced efficiency and accuracy. Integrating material science insights and advanced computational techniques, our model encompasses crucial nonlinearities, including material behavior and geometric variations. Notably, our model's versatility extends to its seamless integration with commercially available structural design software such as ETABS and SAP2000, eliminating the need for complex Finite Element Modeling tools like ABAQUS. Validation against experimental data and comparison with existing models substantiate its reliability and effectiveness. Our model not only streamlines analysis procedures but also furnishes actionable insights for optimizing the design and performance of reinforced concrete structures in practical applications.

Abstract: In the last two decades, great progress in Machine Learning can be seen in various fields of structural engineering including seismic analysis. This paper focuses on the cross-filed of Machine Learning (ML) and seismic engineering and provides an overview on different ML techniques been used in seismic analysis studies, compare these techniques and their application to study the seismic response of timber structures. The comparison of common supervised ML techniques in this paper are Multi Linear Regression, Regression Tree, Regression Forest, K Nearest Neighbor, Support Vector Regression and Artificial Neural Networks. The recent increase in studies of ML is largely focused on Reinforced Concrete (RC) structures but its application for the behavior of timber structures is still to be explored. Timber structures are considered as the best performing material under strong ground motions. However, the problems associated with timber structures are lack of experimental data, standard numerical models and design codes. It has been observed that application of ML in this domain is new but considered as an increasingly dynamic area of high impact result where new horizons of research topics are waiting to be investigated. The review of different studies demonstrated the potential of improving the prediction of seismic performance and structural behavior by the use of ML. These methods allow more efficient and accurate modelling of complex problems than traditional methods.

Abstract: Sand waves are large and transverse bed features, typically with lengths and heights of about 100-500 m and 2-10 m, respectively. The height can grow up to 30% of the average water depth, especially in shallow water conditions. Sand waves can migrate up to around 10 m/year and may profoundly impact subsea infrastructure, such as offshore pipelines and cables, key elements of offshore energy development. In this study, the evolution and migration of sand waves in the Dutch shoreface, North Sea 1986, was investigated using the Regional Oceanographic Modeling System (ROMS) and validated with DELFT3D and survey results from 2000. ROMS is an open-source oceanographic model available for free, created by the United States Geological Survey (USGS) to simulate ocean circulation, sediment transport, and seabed morphodynamics. Calibration of ROMS model conducted by modelling velocity profile in different location and free surface compared to field data. Validation ROMS and DELFT3D result was conducted by comparison the sandwave profile plotting in same graph. ROMS' simulation results agree with DELFT3D's results regarding horizontal grid size; vertical grid level; stretching parameters; time step; sediment diameter; M2 tide velocity which is the most dominant tidal constituent, representing the principal lunar semi-diurnal tide that has a period of approximately 12.42 hours and is caused by the gravitational pull of the Moon; M4 tide velocity which is the overtide of M2, generated by nonlinear interactions, especially in shallow water regions, a harmonic of M2 and has a period of approximately 6.21 hours (half the period of M2); net current in tidal; water depth; and waves. It can be concluded that horizontal grid size and stretching parameters are weakly sensitive to the results. In contrast, sediment diameter, M2 tide velocity, M4 tide velocity, net current in tidal, water depth, and waves may affect the migration significantly. Even though vertical grid level and time step parameters impact the results, these parameters need to be defined with a certain value following the Courant-Friedrichs-Lewy (CFL) condition.

Abstract: Earth retaining wall structures are common civil engineering structures. Estimation of magnitude and distribution of earth pressure on retaining structures under different surcharge loading conditions is essential as they influence the design and overall economy of retaining structures. Numerical modeling using finite element code PLAXIS is used static analysis. 7 m height of non-yielding cantilever retaining wall with and without EPS geofoam structure is studied and 20 m backfill width was considered. In the present study backfill was modeled as Mohr-Coulomb yield criteria and EPS geofoam and wall were modeled as Linear-elastic. EPS geofoam densities namely 12 kg/m³ and 15 kg/m³ and two different geofoam thicknesses 0.107H and 0.143H were used for static analysis. Three different surcharge loading namely 10 kPa,30kPa and 50kPa which were kept at a distance of 2.0 m away from the wall face. In the static analysis earth pressure distribution for wall with and without geofoam were analyzed. Approximately 50% isolation efficiency was reported. At lower surcharge loads the effectiveness of EPS is more as compare to higher surcharge load and with increase in surcharge load, isolation efficiency gradually decreases and isolation efficiency decreases with increase in buffer modulus. Apart from these serviceability criteria was also checked. Serviceability criteria comprise of lateral deformation of EPS geofoam at sand-geofoam interface and backfill surface settlement were studied. Lower EPS geofoam density and higher EPS geofoam thickness reduces higher magnitude of earth pressure but in this combination the backfill surface settlement was coming very high.

Abstract: Increasing demands on component functionality and weight, but also on the use of resources and cost-effectiveness, are leading to the increased use of hybrid components. The combination of diverse materials enables the use of positive properties of the individual material in one component. With regard to the production of hybrid components, the use of hybrid pre-joined semi-finished parts simplifies the joining process, as simple geometries can be used. A well-established process for joining dissimilar materials such as steel and aluminium is rotary friction welding. However, steel and aluminium form brittle intermetallic phases in the joining zone due to their low solubility. Therefore, in addition to the advantages, the use of pre-joined hybrid semi-finished parts also pose new challenges for the following process chain. As a result of thermomechanical stresses during forming, local failure of the joining zone may occur. Due to its small thickness and position within the component, the analysis of the joining zone is only possible by complex destructive testing methods. FE simulation therefore offers an efficient way to design and analyse forming processes for hybrid semi-finished parts, the development of damage in the process design and to reduce damage by process modifications. Therefore, within this study a numerical model of the forming process chain is developed considering inductive heating, transfer and forming. For a realistic description the flow behaviour of the monolithic materials as well as the bonding strength of the pre-joined semi-finished parts is determined in experimental tests. Based on the experiments a damage model is calibrated and used for the analysis of different process variants of hollow forward extrusion of pre-joined hybrid semi-finished parts of steel and aluminium.