This article aims to propose an approach to the stress-based topology optimization of continuous elastic bi-dimensional structures subjected to design-dependent self-weight loads using the ...Bi-directional Evolutionary Structural Optimization (BESO) method. Topology optimization is developed through the minimization of P-norm von Mises stress while satisfying a volume constraint. To implement the algorithm, a consistent sensitivity analysis including design-dependent loads has been developed by the adjoint method. A series of tests has been performed to explore and validate the method through three numerical examples: an L-bracket; a doubly supported beam with one pre-existing crack notch; and a cantilever beam. Comparison between traditional compliance minimization and stress minimization analyses, including design-dependent self-weight loads, shows that the method is an effective way to reduce the maximum stress.
In the power distribution work using the indirect live-line method, it is necessary to frequently lift a tool weighing 15kg and hang it on the electric wire. To reducing the load on workers, this ...paper proposed a motor-less power assist device that can compensate the weight of the tool in the wide range of motion: vertical 600mm, horizontal 600mm, pitch 90deg. The device has weight of 16kg and depth of 200mm, which is lighter and more compact than conventional ones, so that it can be mounted on the side of the bucket of aerial work platform. To verify the effectiveness of this device, we measured the surface myoelectric potential of the forearm flexor muscle group during the overhead wiring work and the time required for the work. Through the experiments, it was confirmed that the load on the muscles was reduced by 90% or more by using this device, and the working time was almost same as the case without assistance.
We present the first full analytical solution to the mode-shape equation of the gravity-loaded Rayleigh–Timoshenko beam, thus describing in closed form the vibration modes of beam–columns, bending ...cables, and stiff marine risers under self-weight. The modes are given in terms of a family of complex “Hankel–Airy” functions, along with their asymptotic expansions, orthogonality relations and series representations. It is shown that the new solutions generalize multiple approximate and asymptotic solutions in the literature and that their numerical approximations closely match past numerical and experimental results as well as models built using the ANSYS software package.
Recent developments have enabled material extrusion additive manufacturing of thermoset-based composite inks on the large scale. In addition, printing out-of-plane components is of broad interest to ...the polymer material extrusion community. This work addresses some of the challenges associated with both large-scale and out-of-plane thermoset material extrusion additive manufacturing by studying the height at which thin overhanging walls collapse. Walls at a range of overhang angles were printed until they collapsed. An optical camera captured the profile of each wall throughout the print, allowing the collapse height to be identified and the geometric fidelity to the programmed angle to be evaluated. Using previously measured rheological properties, predictive models were generated to approximate the collapse height and profile of the deflected walls. First, an analytical model was created to predict the height at which the walls would yield. The analytical model assumes the walls exhibit a perfectly linear profile; however, experiments proved this assumption to be false. Therefore, a finite element simulation was developed to account for the elastic deflection that occurs during printing. The finite element simulation predicts both the yield height and the deflected profile after the deposition of each layer. For the properties of the thermoset ink used here, the yield height predicted by the analytical model and finite element simulation are virtually identical. These predictions match experimental data reasonably well, but minor errors are observed. Accounting for the fully plastic moment appears to explain the small mismatch between experimental data and predictions. Additionally, the finite element simulation provides an excellent prediction of the deflected profile before the wall begins to collapse. By demonstrating that the collapse height and deflected profile of thin overhanging walls can be predicted, this work illustrates how the soft viscoelastic properties of thermoset-based composite inks limit the scale of a key feature required to print some nonplanar components. It also provides a basis to tailor in-process curing systems to suppress deflection and collapse of thin overhanging walls.
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•An uncured epoxy ink for DIW is approximated as an elastic-plastic solid.•Basic beam mechanics analyses accurately predict the collapse of overhangs.•Serial deposition and elastic deformation lead to unique deflection profiles.•Collapse and deflection models provide guidelines for feedstock design.
This paper proposes an approach for the topological design of continuum structures with global stress constraints considering self-weight loads. The rational approximation of material properties is ...employed to describe the material distribution for overcoming the parasitic effect for low densities. The structure volume is used as the objective function to be minimized. The local stress constraints for all elements are aggregated into a global stress constraint using the improved P -norm method. A model for the stress-constrained topology optimization of continuum structures considering the self-weight loads is established. The projection filtering method is adopted to avoid numerical instability, and the topology optimization problems are solved using the method of moving asymptotes. Several numerical examples are presented to demonstrate the validity of the proposed method. The structures obtained by the proposed method can have better performance. The effects of different norm parameters, stress constraints and mesh densities on the topological structures are analyzed.
Introduction This paper adoptes the methods based on parametric study and CPT in-situ test for analysis and calculation, the preliminary analysis is carried out according to the actual construction ...data. By doing this, the self-weight penetration of monopiles can be better and faster predicted and the risks in monopile installation are significantly reduced. Method Modified the design input parameters by API recommended pile capacity theory, combined with error analysis, the predicted self-weight penetration was compared to the real data on site. Result The analysis results show that there is a great difference in prediction of self-weight penetration due to the different reduction strength coefficient \begin{document}$ {S}_{\mathrm{r}} $\end{document} in the process of calculating clay self-weight penetration and pile running analysis. At the same time, the selection of reduction strength coefficient is different between the self-weight penetration and pile running process. Conclusion Through comparative analysis, the value range of clay strength reduction coefficient \begin{document}$ {S}_{\mathrm{r}} $\end{document} of Guangdong sea area is obtained, which can provide a design reference for the following offshore pile penetration operations. It's also proved that the CPT can be used to better predict self-weight penetration and pile running phenomenon.
The application of vertical drains along with preloading to accelerate the consolidation rate of dredged soil has been widely used. However, the conventional analytical or numerical models cannot ...predict the nonlinear finite-strain consolidation behavior of dredge-soil deposits accurately because the vertical drains are installed in the middle of a self-weight-consolidation process. This paper establishes a mathematical and numerical model for a 2-D axisymmetric nonlinear finite-strain consolidation, for which the self-weight consolidation and the radial drainage through vertical drains are considered. Besides, a series of lab-scale self-weight-consolidation tests were conducted, which can simulate the vertical-drain installation. Experimental results along with those of the simplified method (Lee et al., 2016) were then utilized to verify performance of the proposed model. The results demonstrate that the proposed model appropriately predicts the nonlinear finite-strain self-weight consolidation behavior of dredged soils, and its application with vertical drains is suitable for designing dredged-soil improvement. Moreover, the most important advantage of the proposed model is to optimize the schedule of dredging/landfilling construction.
•Development of numerical model for axisymmetric nonlinear finite-strain self-weight consolidation.•Lab-scale self-weight-consolidation tests were conducted to verify the model.•Predicting consolidation behavior of dredged soil in application of vertical drains.
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