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In the present study, a topology optimization method of thermal-fluid-structural problems is researched to design the three-dimensional heat sink with load-carrying capability. The optimization is formulated as a mean temperature minimization problem controlled by Navier-Stokes (N-S) equations as well as energy balance and linear elasticity equations. In order to prevent an unrealistic and low load-carrying design, the power dissipation of the fluid device and the normal displacement on the load-carrying surface are taken as constraints. A parallel solver of multi-physics topology optimization problems is built-in Open Field Operation And Manipulation (OpenFOAM) software. The continuous adjoint method is adopted for the sensitivity analysis to make the best use of built-in solvers. With the developed tool, the three-dimensional (3D) thermal-fluid topology optimization is studied. It is found that the Darcy number, which is suitable for fluid design, may cause severe problems in thermal-fluid optimization. The structural features of 3D thermal-fluid-structural problems are also investigated. The “2D extruded designs” are helpful to improve the structural stiffness, and channels with a larger aspect ratio in high-temperature areas improve the cooling performance.

The moving morphable components (MMC)-based approach has advantages in describing geometry explicitly, feature size controlling, etc., and it has been successfully used for the topology design of bearing structures. In this work, the MMC-based approach is extended to thermal-fluid design which is formulated as a heat transfer maximization and fluid power dissipation minimization problem controlled by Navier–Stokes (N–S) and energy balance equations. Aiming at describing the geometry of bend pipes which usually have a larger curvature than the bearing structures, a cubic order component with elliptic joints is proposed. In order to limit the minimum width of pipes according to the manufacturing capacity, a feature size control technique is developed. The algorithm is investigated on a two-dimensional numerical model by comparing with density-based method and MMC approach with quadratic components. In our tests, besides the advantage of feather size controlling, the developed MMC also achieves lower objective values than the other two methods.

A topology optimization approach is developed to design the conformal cooling system for injection molding in this paper. During the design process, the cycle-averaged approach is used to simplify the analysis of the cooling process, and the boundary element method (BEM) is adopted to solve the governing equations and calculate the sensitivities. The optimization starts from the complicated network of channels, and the radius of each channel section and the location of each node are selected as the design variables. The topology of the cooling system can be modified by deleting excessively thin channel sections. We pick out two representative example models with areas that are hard to cool to test the effectiveness of the proposed optimization approach. The results show that our method can improve both efficiency and uniformity of the cooling process.

The liquid-cooled heat sink is an effective and robust cooling device and has been widely used in the industry. The fluid-thermal topology optimization approaches have been adopted for the heat sink design by many researchers. However, none of these works considered the optimization of heat source distribution. This work focuses on the synergic design of the cooling channels and the layout of heat sources with diverse intensities. A hybrid topology optimization approach is adopted, in which the channels are implicitly described with pseudo-density while the heat sources are considered as moving components. The maximum temperature of the system is taken as the objective and constrained by the fluid power dissipation. In order to avoid unrealistic designs such as suspended structures, the stiffness of the structure is considered as a constraint. Considering when heat sources have diverse intensities, the initial locations of the heat sources could significantly affect the optimal result. Aiming at this problem, a heuristic algorithm that can redistribute the heat sources efficiently during the optimization process by exchanging their locations is developed. The topology optimization is performed with a parallel solver developed in Open Field Operation And Manipulation (OpenFOAM) framework. The numerical tests show that the influence of the heat source distribution on the cooling performance could be even higher than the cooling channel design, and the synergic topology optimization method is an effective way to design high-performance heat sink.

This paper develops a framework that tackles the Pareto optimum of injection process parameters for multi-objective optimization of the quality of plastic part. The processing parameters such as injection time, melt temperature, packing time, packing pressure, cooling temperature, and cooling time are studied as model variables. The quality of plastic part is measured by warp, volumetric shrinkage, and sink marks, which is to be minimized. The two-stage optimization system is proposed in this study. In the first stage, an improved efficient global optimization (IEGO) algorithm is adopted to approximate the nonlinear relationship between processing parameters and the measures of the part quality. In the second stage, non-dominated sorting-based genetic algorithm II (NSGA-II) is used to find a much better spread of design solutions and better convergence near the true Pareto optimal front. A cover of liquid crystal display part is optimized to show the method. The results show that the Pareto fronts obtained by NSGA-II are distributed uniformly, and this algorithm has good convergence and robustness. The pair-wise Pareto frontiers show that there is a significant trade-off between warpage and volumetric shrinkage, and there is no significant trade-off between sink marks and volumetric shrinkage and between sink marks and warpage.

Microinjection-molded products with microfeatures are widely used in the biomedical field, microlens, etc. In this paper, a microinjection mold with venting design is fabricated for producing a polylactic acid (PLA) micropillar array product. The effect of injection velocity on the filling fraction is investigated. Results show that the farthest microcavity in the array to the sprue is readily filled with PLA melts at the given injection velocity conditions, while the nearest microcavity is the worst one in term of filling fraction, although increasing injection velocity can efficiently improve the entire filling fraction. By seriously analyzing the temperature and pressure from a simulation point of view, it reveals that the special geometrical structure of the product provides the condition which causes all the significant and interesting filling phenomena to appear in the experiment and simulation. This mechanism is beneficial to understand the filling behaviors of microfeatures and helps us to improve the replication of the product.

Many injected engineering polymer structures have to suffer the external load conditions (thermal load, impact load, etc.). In this case, service-induced stress concerns safety of human and the plastic engineering structure. In this study, geometrical design factors are connected with the engineering service stress of the polycarbonate (PC) window which is in thermal and pressure load conditions for the first time. The mold is constructed by an injecting gate with six design parameters and a type of spherical spiral conformal cooling system. The thickness of the product cavity is characterized by a linear function. Molding defects (warpage and residual stress) are taken into consideration sufficiently. In order to reduce the service stress, kriging surrogate model is employed to interpolate the implicit service stress function with respect to 14 geometrical design parameters, expected improvement function optimization method is used to search the optimum result, and log-exponential smoothing function method is used to simplify the multi-constraints. The comparison shows that the service stress is affected by the mold construction greatly, and the optimized mold and product design scheme are preferred to improve the service quality of the PC window.

This research dealt with a novel method of fabricating green composites with biodegradable poly (lactic acid) (PLA) and natural hemp fiber. The new preparation method was that hemp fibers were firstly blending-spun with a small amount of PLA fibers to form compound fiber pellets, and then the traditional twin-screw extruding and injection-molding method were applied for preparing the composites containing 10–40 wt% hemp fibers with PLA pellets and compound fiber pellets. This method was very effective to control the feeding and dispersing of fibers uniformly in the matrix thus much powerful for improving the mechanical properties. The tensile strength and modulus were improved by 39 and 92 %, respectively without a significant decrease in elongation at break, and the corresponding flexural strength and modulus of composites were also improved by 62 and 90 %, respectively, when the hemp fiber content was 40 wt%. The impact strength of composite with 20 wt% hemp fiber was improved nearly 68 % compared with the neat PLA. The application of the silane coupling agent promoted further the mechanical properties of composites attributed to the improvement of interaction between fiber and resin matrix.

Coconut shell, as a renewable biomass resource, has rich carbon source potential. In this study, the constitutive relationship between the microstructure of coconut shell carbon materials and the sodium ion storage performance is systematically investigated by combining computational simulation and experiment, and a multi-scale computational model from the atomic to micrometer scale is established, which reveals the key factors of the synergistic influence of microporous-mesoporous hierarchical structure and oxygen-containing functional groups on the sodium storage mechanism. The optimized coconut shell carbon materials based on theoretical predictions show excellent electrochemical properties, achieving the computationally guided efficient conversion of biomass resources into high-performance anode materials for sodium ion batteries, and providing a new idea for the rational design of carbon-based energy storage materials.

The electrospun fibrous membranes used as lithium-ion battery separators have been widely studied due to the advantages of high porosity, large specific surface area and adjustable structural characteristics. In order to obtain thermal stable and high-strength electrospun fibrous membranes for lithium-ion battery separators, the oriented poly(phthalazinone ether sulfone ketone) (PPESK) fibrous membranes were fabricated and then hot pressed with two pieces of membranes overlaid perpendicularly. The prepared hot-pressed composite oriented PPESK membranes show high tensile strength of 22.8 MPa at both horizontal and vertical directions. The hot-pressed oriented PPESK membranes are thermally dimensional stable even at the high temperature of 200 °C. In addition, the novel PPESK fibrous membranes exhibit high porosity (70%), superior electrolyte uptake (525%), low interfacial resistance (268 Ω) with electrodes and excellent ionic conductivity (1.39 mS cm −1 ). The simulated cells using the new separators show high discharge capacity and excellent rate capability, which demonstrates the novel membranes have potential to be used as separators for power lithium-ion batteries.