Papers by Keyword: Dynamic

Abstract: Given the importance of enhance the performance of oil separators in production field, this research study the separation process through simulations based on a real field data, WQ-2 south of Iraq-Basra. By implementing both dynamic and steady-state approaches in Aspen HYSYS V.14, the optimization was carried out for each approach for comparison. Results from the steady-state simulation revealed limited improvement, with closely converging iterations and changes applied to only one variable at a time. In contrast, the dynamic simulation given more realistic and favorable results, as manual adjustments were applied in a real-time response to the actual field dynamics range and conditions. The result shows that the maximum OVFR=15050 m³/h and CO=0.1999099 at T= 60 °C and P= 15 barg for static model, while the OVFR=1580.9 m³/h, CO=0.0093 at P=14 barg, T=76 °C where the operation time 120 min for dynamic. Compared to the static approach, the dynamic approach was efficient to reach better performance when the selected parameters were optimized and that led to a substantial improvement in the separation efficiency. Therefore, the dynamic simulation could be considered a mandatory approach when the overall separator efficiency need to be enhanced.

Abstract: Fiber-reinforced polymers (FRP) bars have gained widespread recognition as a viable alternative to steel reinforcement in concrete structures over the past decades due to their advantages in corrosion resistance, durability, and lightweight properties. However, existing research and current design codes do not adequately address the dynamic compressive response of FRP bars under high-impact loading conditions. This gap in knowledge presents a significant challenge in accurately predicting the response of FRP-reinforced structures under extreme loading events. Therefore, it is essential to investigate the response of FRP bars under dynamic loading conditions across a range of strain rates to improve design codes and ensure the reliability and safety of structures subjected to such conditions. This study presents an experimental program conducted on basalt FRP (BFRP) bars subjected to dynamic testing using the Split Hopkinson Pressure Bar (SHPB) apparatus. The 12-mm BFRP bars are subjected to impact loading at high strain rates ranging from 345 to 1300 s^-1. These varying strain rates are achieved by adjusting the pressure of the impact bar. A high-speed camera is employed to capture the failure mechanisms and provide visualization of the deformations during loading. The study focuses on evaluating the stress-strain relationship and failure modes of the tested BFRP bars under various loading rates. The results revealed that at higher strain rates of ∼1300 s^-1, BFRP bars lost 40% of its compressive strength when compared to its quasi-static strength (tested at 3.5 x 10^-4 s^-1). At lower strain rates (∼345 s^-1), 20% of the quasi-static strength is lost. At intermediate strain rates (∼590-740 s^-1), one sample showed a strength reduction of 26%, while another sample showed a strength gain of 10%. This proves that BFRP bars are highly strain-rate dependent. Additionally, the results show relatively significant variation in the behavior of the samples at similar strain rates, indicating microstructural differences between them.

Abstract: The numerical analysis using finite difference method to study static and dynamic performance of embankment dams is a complex process, in which the materials behavior, soil-dam foundation interaction, hydraulic conditions and saturation effects, should be taken into account. In this study, static and dynamic analysis of Keddara earth dam, located in Boumerdes region (Algeria), is conducted by a numerical analysis using finite difference method (FLAC 3D), with the objective to define its behavior in terms of settlement, strain and pore pressure variation, during its construction and operation. Two stages are considered; the dam construction stage and water filling stage. In this way, two mathematical models are considered for the static analysis; the elastic model and Mohr-Coulomb model. To conduct a coupled dynamic analysis a real earthquake record is used and the interaction between the fluid and solid phases is taken into account.

Abstract: This paper introduces the analytical solutions of complex behavior analysis utilizing high-order shear deformation plate theory of functionally graded FGM nano-plate content consisting of a mixture of metal and ceramics with porosity. To incorporate the small-scale effect, the non-local principle of elasticity is used. The impact of variance of material properties such as thickness-length ratio, aspect ratio, power-law exponent and porosity factor on natural frequencies of FG nano-plate is examined. Compared to those achieved from other researchers, the latest solutions are. Using the simulated displacements theory, equilibrium equations are obtained. Current solutions of the dimensionless frequency are compared with those of the finite element method. The effect of geometry, material variations of nonlocal FG nano-plates and the porosity factor on their natural frequencies are investigated in this review. The results are in good agreement with those of the literature.

Abstract: This study aims to analyze the stress that occurred on the automotive coil spring made of SAE 5160 carbon steel due to various types of road surfaces. The 60-second strain signals measured on a coil spring of a car being driven on a flat, uphill, and downhill road surface were used as the loads in these dynamic analyses. The analysis results showed that the maximum stress occurred on the inside of the spring in the second coil from the top. The results of this dynamic analysis also showed that the three types of road surfaces provided almost the same stress. The downhill road surface gave the highest stress, which was 0.622 GPa, followed by flat road (0.621 GPa) and uphill road (0.62 GPa). The reasons for this are the shifting of the vehicle load to the front wheels together with the braking effect when driving downhill.

Abstract: This work evaluates the mechanical and dynamic behavior of recycled polycarbonate (rPC) from industrial waste. This study aims to verify whether the recycled process adopted for polycarbonate promotes both mechanical and dynamic properties values under compressive stress, similar to those found for virgin polycarbonate. The mechanical recycling of the rPC was carried out using the thermoforming technique in a thermal press. Two tests were carried out to evaluate the dynamic response of rPC. The quasi-static compression test was performed on a universal machine. The dynamic in a split Hopkinson pressure bar was performed with three different strain rates. The results showed that the mechanical and primary recycling adopted in this work promoted values of yield stress in compression (77 MPa) and dynamic (up to 118 MPa), close to or superior to those reported so far in the literature.

Abstract: The known methods of calculation of oscillation amplitudes of massive foundations of machines taking into account damage are analyzed in the article. It is established that the method set out in the building codes allows to determine the amplitudes of the foundation oscillations at any point of the foundation, approximately enough. This technique does not take into account the interaction with the soil of the deepened foundations, but takes into account only the physical and mechanical characteristics under the sole of the foundation. The authors propose a finite element method (FEM) calculation using the Plaxis 7 software package installed on a personal computer and a vibrometer. The result is the oscillation amplitude of the massive foundation. The presence of cracks and damage increases the magnitude of the oscillation amplitudes from the dynamic impact. If you make timely planned repairs to the foundations, the amplitude of the oscillations can be reduced.

Abstract: Maintenance optimization is applied by organizations to develop robust maintenance programs while attempting to establish a trade-off between competing maintenance requirements and resources. For this reason, maintenance decisions derived from maintenance optimization models are adversely affected, if (a) the maintenance objective(s) applied as input to the optimization models is not dynamically reviewed as the organizations environment context changes, and (b) there is continued use of historical maintenance objectives, oftentimes the practice for organizations lacking a framework for selecting maintenance objectives (MO’s). To address this, an interactive maintenance objective selection framework for stakeholders that aligns with and considers changes in the organization’s business, operational, and technical context, where dynamic maintenance objectives are selected and prioritized for application in real-life maintenance optimization models is proposed. The framework uses an analytic network process (ANP) based methodology, for selecting the relevant MO’s in view of competing dynamic criteria, for instance, employing remanufactured spares to optimize availability and maintenance cost. The applicability of the framework is demonstrated in case studies of companies operating in diverse industries like aviation and manufacturing in Africa. The study highlights the effects of dependencies between competing maintenance objectives, where the dependencies invariably influence how organizations prioritize MO’s to use for maintenance optimization programs. The additional value of the proposed framework lies in assisting organizations select maintenance objectives applicable to the organization while considering competing objectives and evolving business context.

Abstract: Software developers have shown a lot of interest in using agile approaches and methods to manage projects. The Agile Manifesto in 2001 provided a good basis to use this as it formulated its 4 values and 12 principles. Adaptability was a common feature in the Agile Manifesto to make agility happen and there appears a need to combine dynamism to ensure agility takes a more concrete and effective role. Whilst the term adaptability is discussed more often than dynamism by most researchers, the clarity in its meaning needs improvement as the terms are used interchangeably. This paper proposes a useful clarity on its differences and how it should be used. In addition, this approach would also facilitate the current research interest in mixing and combining software development methodologies to create hybrid versions as pure methods (traditional and agile) have not worked well in most software projects.

Abstract: In the practice of civil engineering, the methods of impact diagnostics of materials find their application, allowing quickly and accurately measure the required strength characteristics at any point in the structure. Impact methods offer many advantages, for example, at smaller dimensions can be developed big the contact force, it can be recorded more information about the response of the material to dynamic impact and others. This approach is widely used in determining the hardness of materials and makes it possible to determine the complex mechanical characteristics: yield strength, ultimate strength, and elongation. In the paper we consider the axisymmetric problem of the impact of the conical indenter on the plate, laying on Winkler Foundation under elastic-plastic deformation. The solution is based on the phenomenological model of elastic-plastic indentation in a quasistatic formulation. The general deformations of the plate are considered elastic, and the local, in the contact zone, are elastoplastic. The main characteristics of the impact are determined: the force of the contact interaction, the local indentation, the contact time. The device and methods of determining the strength characteristics of plates under specified conditions of impact were developed on the basis of obtained solutions. The proposed method has been tested on many building structures: bridges, trusses, structural structures of artificial structures, reinforcement bars, welded joints.