This paper presents a new discrete parametrization method for simultaneous topology and material optimization of composite laminate structures, referred to as Hyperbolic Function Parametrization ...(HFP). The novelty of HFP is the way the candidate materials are parametrized in the optimization problem. In HFP, a filtering technique based on hyperbolic functions is used, such that only one design variable is used for any given number of material candidates. Compared to state-of-the-art methods such Discrete Material and Topology Optimization (DMTO) and Shape Function with Penalization (SFP), HFP has much fewer optimization variables and constraints but introduces additional non-linearity in the optimization problems. A comparative analysis of HFP, DMTO and SFP are performed based on the problem of maximizing the stiffness of composite plates under a total volume constraint and multiple manufacturing constraints using various loads, boundary conditions and input parameters. The comparison shows that all three methods are highly sensitive to the choice of input parameters for the optimization problem, although the performance of HFP is overall more consistent. HFP method performs similarly to DMTO and SFP in terms of the designs obtained and computational cost. However, HFP obtains similar or better objective function values compared to the DMTO and SFP methods.
As the planet warms, keeping cool without releasing greenhouse gases will be a challenge, but radiative cooling technology is poised to meet this goal. Hundreds of radiative cooling materials have ...been reported in the literature to yield acceptable cooling performance, but there is a lack of guideline for engineers to select the suitable candidates for commercialization. In order to tackle this problem, we gathered information on 55 radiative cooling materials reported in the literature according to our selection criteria and grouped them into four categories: multilayer structure, metamaterial, randomly distributed particle structure, and porous structure. Using a comparison method that objectively evaluated their cooling performance and commercialization potential, we found that the polymer-based porous structure and randomly distributed particle structure without reflective metal layer tend to be more promising for commercialization because of their superior cooling performance, low cost, ease of manufacture, high scalability and compatibility. Furthermore, we proposed an approach for the design and optimization of potential radiative cooling materials. This review will not only provide engineers with guidelines for selecting the best materials in applying and commercializing this technology, but will also enable researchers to propel this technology forward through improved material design in the future.
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•The cooling performances of 55 radiative cooling materials were evaluated.•Porous and randomly particle structure without metal layer are more promising.•An approach for the design of potential radiative cooling materials was proposed.
Excessive phosphorus is one of the main reasons leading to eutrophication that causes severe ecosystem imbalance and negative human health impacts. In this study, several chitosan (CS)/lanthanum (La) ...hydrogel beads were first synthesized and tested for phosphorus removal. The stable cross-linked CS/La hydrogel bead prepared with the optimized conditions of 10 wt% La/CS and 1.5 mL of 5% glutaraldehyde demonstrated exceptional performance in the removal. It removed phosphate effectively from an aqueous solution in the pH range from 2 to 7. The complete phosphate uptake was achieved at contact time of 6 h under the completely mixing batch condition. The experimental maximum adsorption capacity of 107.7 mg g−1 was observed at solution pH 4. The phosphate adsorption was well described by the Freundlich isotherm and the intraparticle surface diffusion model. Furthermore, the adsorbent was effectively regenerated and reused in a five-cycle adsorption-desorption operation. The removal of phosphate can be attributed to electrostatic attraction and ion exchange. Moreover, the bead was capable of removing heavy metals: copper, zinc and lead. This adsorbent may be served as a cost-effective material for the treatment of phosphorus-contaminated water so as to minimize the occurrence of eutrophication.
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•Chitosan/lanthanum hydrogel bead can remove phosphate effectively.•It can remove cationic heavy metals: Cu, Pb, and Zn.•A rapid phosphate removal is completed at contact time of 6 h.•The uptake is due to electrostatic attraction and ion exchange.
Laminated composite structures have a distinct inherent potential for optimization due to their tailorability and their associated complex failure mechanisms that makes intuitive design remarkably ...difficult. Optimization of such is a maturing technology with many criteria and manufacturing constraints having been successfully demonstrated. An approach for high-cycle fatigue is however yet to be developed in a gradient-based context. Thus, the objective of this work is to introduce a novel framework that allows for effective high-cycle fatigue optimization of laminated composite structures.Offset is taken in the Discrete Material and Thickness Optimization parametrization, which allows for simultaneous material and thickness selection for each layer that constitute a laminate. The fatigue analysis approach is based on accumulating damage from all variable-amplitude cycles in an arbitrary spectrum. As high-cycle fatigue behavior is highly nonlinear, it is difficult to handle in optimization. To stabilize the problem, damage is scaled using an inverse P-mean norm formulation that reduces the nonlinearity and provides an accurate measure of the damage. These scaled damages are then aggregated using P-norm functions to reduce the number of constraints. This is convenient, as it allows sensitivities to be efficiently calculated using analytical adjoint design sensitivity analysis. The effectiveness of this approach will be demonstrated on both benchmark examples and a more complicated main spar structure.
A computational multiscale design of micro-architected compliant mechanisms is presented. The optimal design is performed with spatially varying material properties at the macro scale where the ...homogenized stiffness tensor is considered as the design variable (free material optimization). Mapping the obtained spatially-varying properties onto micro-architected materials is achieved using inverse design topology optimization. The originality of this work lies in using a database assisted framework in order to obtain the optimal design. Two approaches are compared: the first one does not make use of the database wheres the second approach is driven by an adequate material database. For the first approach, the required materials are constructed a posteriori while the materials are constructed a priori and stored in a catalog for the second approach. This catalog is then exploited during the macro-optimization. The performances of both methods is compared via different examples that highlight the advantages of the database strategy in terms of the required micro-architected materials feasibility.
•A data assisted topology optimization design of compliant mechanisms ensuring achievable architected materials at the micro-scale.•Separation of the design optimization to a macro-scale free material optimization and a micro-scale inverse homogenization topology optimization.•Improvement of the final cost function results compared to mono-scale SIMP topology optimization.
•Multi-material topology optimization (MMTO) applied to a microchannel heat sink.•2D conjugate heat transfer model with LTE for model verification.•Heat transfer enhancement due to solid features and ...metal foam distribution.•MMTO outperforms topology optimization in increasing PEC of about 59–84 %.•Percentage weight saving with respect to baseline case from 80 % to 83 %.
Microchannel heat sinks (MCHSs) play a pivotal role in numerous fields, including electronics cooling, chemical processing, and biomedical applications. Conventional design approaches for MCHSs often rely on predefined geometries or empirical trial-and-error methods, limiting the exploration of the design space and leading to suboptimal performance. Density-based topology optimization (TO), on the other hand, leverages gradient-based procedure to systematically explore and optimize the material distribution within MCHSs. On these premises, this work aims to study the combined use of porous materials like metal foams and TO in a multi-material topology optimization (MMTO) to improve MCHS thermo-fluid dynamic performance. Starting from a baseline design, a 2D numerical model has been developed with a conjugate heat transfer formulation, i.e., the governing equations of heat conduction inside solid material, and forced convection inside fluid/foam domains. For the multi-material topology optimization, the solid isotropic material with penalization (SIMP) model with two pseudo densities is used to handle the three phases problem. By strategically placing solid and foam materials, the aim is to balance the trade-off between low-pressure drop and high heat transfer rate. Overall, the optimized designs, i.e., TO and MMTO-based, turn out to be nonintuitive and show significantly higher thermo-fluid dynamic performance when both compared to a baseline case, with a reduction in the required pumping power up to 88 % at constrained inlet velocity. The MMTO microchannel, compared to the one developed with topology optimization, improves the performance evaluation criteria (PEC) of about 59–84 % at different fixed pressure drop and inlet velocities. Moreover, the weight saving – with respect to the baseline case – is assessed to range from 80 % to 83 %. This newly-designed devices might be really helpful to improve the thermal performance of available microchannel heat sinks.
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A combined formulation is proposed for modeling and material optimization of rotating in-plane functionally graded (IFG) thin-shell blades with variable thickness in this paper. The aim of this work ...is to study the vibration characteristics and optimize the IFG volume fraction of the rotating blade model. The isogeometric approach (IGA) and metaheuristic algorithms are employed to find the compositional profile of a two-constituent material blade with the goal of maximizing the fundamental frequency. By considering the rotating speed, the vibrational behaviors of the blades are predicted based on the thin-shell theory and IGA. The different effects due to the rotating speed, variable thickness and IFG materials are considered in the governing equations. For the optimization model, the high-order non-uniform rational B-spline (NURBS) can ensure a smooth material composition profile with fewer design variables. The changing of material composition at control points in plane provides more possibilities for blade material design. Several comparison studies are performed to verify the accuracy of current models for dealing with the vibration behaviors and optimizing the material distribution of the thin-shell blades. The correctness of the combined optimization approach is also proved by comparing those optimal results of two algorithms. Through the optimization process, the optimal material distribution of thin-shell blades with uniform and variable thickness is obtained.
•A rotating IFG variable thickness thin-shell blade model is established.•The effects of the rotation speed, variable thickness and IFG materials are considered.•The IGA and metaheuristic algorithms are firstly used to optimize a two-constituent material blade.•The optimal material distribution of thin-shell blades with uniform and variable thickness is obtained.
In this paper, a concurrent multi-scale optimization framework is established for hybrid composite plates and shells, where fiber volume, fiber orientation and stacking sequence can be optimized ...simultaneously. Firstly, a finite element model of shell structure that contains patches is established. Then, the candidate material set of hybrid composites is calculated and assembled by different combinations of fiber volume, fiber orientation and stacking sequence at the material and laminate scales. Furthermore, the Discrete Material Optimization (DMO) method is employed to perform the concurrent multi-scale optimization. Two illustrative examples are used to verify the effectiveness of the proposed optimization framework, including a simple example of a hybrid composite plate and a complex engineering example of a double serpentine nozzle. In comparison to optimal results by the traditional constant-stiffness design method, the optimal results of the proposed framework achieve significant 19.8% and 14.0% improvements in the fundamental frequency under the constraint of material cost, respectively. It can be concluded that the proposed concurrent multi-scale optimization framework has huge potential in adaptive stiffness tailoring for hybrid composite plates and shells with complex multi-scale design variables, which can make full use of hybrid composite materials to improve the structural performance against vibration while maintaining the low material cost.
•The effect of materials contents on pavement performance of cold recycled mixture were studied.•Optimal materials content combination was determined by multi-index weighted grey target ...method.•Fatigue Crack characteristic and resistance mechanism was revealed by SEM test.•Cement-emulsified asphalt mortar improved the microstructure and the interfacial deformation.
To enhance the selection of material content for a cold recycled mixture of emulsified asphalt in hot and rainy areas, the effect of emulsified asphalt content, cement content and Reclaimed Asphalt Pavement (RAP) content on high temperature properties, moisture stability and the fatigue properties of cold recycled mixture were investigated. Based on multi-index weighted grey target theory, the performance of cold recycled mixture were analyzed and the material content were optimized. Then, the crack resistance mechanism of the cement-emulsified asphalt mortar was revealed via a scanning electron microscopy test. The results showed that emulsified asphalt content and cement content mainly affected the high temperature properties, while the effect of the RAP content on water stability was the most significant, and the fatigue performance was significantly affected by various factors under different the stress ratio. The proportions of 3.8% emulsified asphalt, 2% cement and 80% RAP were recommended by grey target optimization. Plentiful hydration products were found positioned in the interfacial crack between the asphalt and aggregate, enhancing the interfacial strength and improving the micro-interface deformation of the cold recycled mixture.
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