Jiquan Li

Zhejiang University of Technology · college of mechanical egineering

Magnesium alloy materials are often affected by cyclic stress, resulting in fatigue fracture due to changes in mechanical properties. In this study, external cyclic loads were introduced to simulate the loading of AZ91D (Mg-9Al-0.5Zn) parts. Tensile tests under static and external circulation loads were performed on the same specimens, and the effe...

In micro injection molding, the cavity thickness and surface roughness are the main effects factors of polymer flow in the die designing and affect the quality of molded products significantly. In this study, the effects of cavity thickness and roughness of cavity surface were investigated mainly on polymer flow during molding and on the roughness...

High-quality concept design is a key factor of successful product performance and efficiency. Conventional conceptual design morphological chart serves to combine product concept designs. Nevertheless, the huge number of combined concept designs and how to reduce is an important research point. In this paper, concepts design combined after refineme...

At present, the qualified rate of large thin-walled magnesium alloy castings is low. In this study, the effects of mold structure and process parameters were investigated to improve the production qualification rate of castings. The filling process of die castings was simulated by numerical simulation technology to optimize their structure. On the...

Parts with microstructure arrays have been widely used in biotechnologies and optical technologies, and their performances are affected by replication uniformity. The uniformity of the microstructure is still a challenge in micro-injection molded parts and is greatly affected by the cavity thickness and process parameters. In this study, the replic...

A critical problem in engineering reliability analysis is obtaining an accurate failure probability with a high computational efficiency. This study aims to present failure probability estimation under the conditions of uncertain input variables and their uncertain distribution parameters. An adaptive Kriging model of failure probability with respe...

Isotactic polypropylene (iPP) has been increasingly used owing to its advantages. However, the variation in crystallinity and service temperature of this material will affect its mechanical behaviour significantly, resulting in a lightweight material and an unreliable fatigue resistance prediction. In this study, a prediction model was established...

Magnesium alloy materials are often affected by cyclic stress, resulting in fatigue fracture due to changes in mechanical properties. In this study, external cyclic loads were introduced to simulate the loading of AZ91D(Mg-9Al-0.5Zn) parts. Tensile tests under static and external circulation loads were performed on the same specimens, and the effec...

Conceptual design decision plays a vital role in the new product development as it affects the direction of subsequent design activities. However, pertinent literature advocates the uncertainty assessment of the terminal scheme, but ignores the function interactions and the uncertain behavior selections derived from user’s preferences in the functi...

A multi-objective uncertainty optimization design methodology of hybrid composite structures considering multiple-scale uncertainties is presented in this paper. The hybrid composite structures comprise of multiple materials with different types and volume ratios of matrix and fibers. The objective is to maximize the first-order natural frequency a...

As the total flow rate and passage number increase, the quality of the passage arrangement has an important influence on the thermal efficiency of a multi-stream plate-fin heat exchanger (PFHE). The operating conditions are uncertain due to changes in environmental and product requirements, which affect the design of passage arrangements. If this i...

A burn mark is a sort of serious surface defect on injection-molded parts. In some cases, it can be difficult to reduce the burn marks by traditional methods. In this study, external gas-assisted injection molding (EGAIM) was introduced to reduce the burn marks, as EGAIM has been reported to reduce the holding pressure. The parts with different sev...

Modeling and simulation of the morphology evolution of immiscible polymer blends during injection molding is crucial for predicting and tailoring the products’ performance. This paper reviews the state-of-the-art progress in the multiscale modeling and simulation of injection molding of polymer blends. Technological development of the injection mol...

Warpage is a typical defect for injection-molded parts, especially for crystalline parts molded by rapid heat cycle molding (RHCM). In this paper, a prediction method is proposed for predicting the warpage of crystalline parts molded by the RHCM process. Multi-layer models were established to predict warpage with the same thicknesses as the skin-co...

For engineering products with uncertain input variables and distribution parameters, a sampling-based sensitivity analysis methodology was investigated to efficiently determine the influences of these uncertainties. In the calculation of the sensitivity indices, the nonlinear degrees of the performance function in the subintervals were greatly redu...

Conceptual design evaluation plays a crucial role in new product development (NPD) and determines the quality of downstream design activities. Currently, most existing methods focus on fuzzy quantitative the evaluation information of multi-objectives in conceptual schemes selection. However, the above process ignores the various customers' preferen...

Conceptual design decisions form part of a multi-objective evaluation process that plays a critical role in product development. However, when there is interaction among the evaluation objectives, existing decision methods are difficult to determine the influence degree of each objective on the overall design desirability, which can lead to an unre...

The medical device conceptual design decision-making is a process of coordinating pertinent stakeholders, which will significantly affect the quality of follow-up market competitiveness. However, as the most challenging parts of user-centered design, traditional methods are mainly focusing on determining the priorities of the evaluation criteria an...

The morphology of polymer blends plays a critical role in determining the properties of the blends and performance of resulting injection-molded parts. However, it is currently impossible to predict the morphology evolution during injection molding and the final micro-structure of the molded parts, as the existing models for the morphology evolutio...

A multiple-scale uncertainty optimization design framework is established for hybrid composite structures, where the stacking sequence and material patches are optimized simultaneously considering micro-scale uncertainty material and strength parameters. Firstly, the uncertainty propagation and performance calculation are implemented based on the f...

Reliability is a major performance index in the electromechanical product conceptual design decision process. As the function is the purpose of product design, the risk of scheme design is easy to be caused when there is a failure (i.e., function failure). However, existing reliability analysis models focus on the failure analysis of functions but...

Many non-probabilistic approaches have been widely regarded as mathematical tools for the representation of epistemic uncertainties. However, their heavy computational burden and low computational efficiency hinder their applications in practical engineering problems. In this article, a unified probabilistic representation approach for multiple typ...

The optimum conceptual scheme is mostly selected based on qualitative decision-making evaluation methods in conceptual design stage of engineering product, which lacks quantitative verification and evaluation. To solve this problem, quantitative selection method of product conceptual scheme based on bond graph is proposed. Through analyzing the cor...

The paper proposes a multi-scale uncertainty quantification framework of composite laminated plates. The micro and macro uncertainty parameters are represented by random and interval variables according to available uncertainty information. The data-driven Polynomial Chaos Expansion model is constructed, where polynomial coefficients of random vari...

Temperature greatly influences the mechanical response of acrylonitrile butadiene styrene (ABS). The tensile behavior of ABS was explored in this study. The tensile experiments were conducted at a wide range of temperatures (from 40°C to 130°C). A model was established to reveal the quantitative relationship between temperature and tensile behavior...

The microstructure of a molded product considerably influences its macroscopic properties. In this study, the influence of molding process on microstructure, tensile property, and surface quality was explored on the glass fiber-reinforced polypropylene (GFRPP) parts molded by rapid heat cycle molding (RHCM) and conversion injection molding (CIM). T...

The pressure drop increases along with the decrease in the flow maldistribution in the two-stage distributing inlet headers of a plate-fin heat exchanger. To solve this issue, we proposed a new inlet header configuration with splitter plates to decrease the flow maldistribution and pressure drop simultaneously. We used computational fluid dynamic t...

The purpose of this paper is twofold. The first is to numerically investigate and reveal the effect of polymer viscoelasticity on the retraction of a deformed drop using the lattice Boltzmann (LB) method and polymer kinetic theory. More importantly, the second is to propose a novel method to evaluate the interfacial tension between polymer melts ba...

External gas-assisted injection molding (EGAIM) has been used to reduce the sink marks of amorphous polymer products, but that of crystalline polymer products has not yet been reported. EGAIM of a crystalline polymer product was investigated in this study, and the influences of process parameters on the sink marks were discussed based on experiment...

The available amount of input data for uncertain parameters of composite laminated plates can vary, and the uncertain parameters can be decomposed into strong statistical variables, sparse variables and interval variables. Therefore, a new reliability optimization design methodology for composite laminated plate considering these uncertainty types...

A product service system composed of products, services, hardware and software support, and stakeholders enhances the added value and competitiveness of products through resource integration. To reduce the input in servitization and improve feasibility, manufacturers tend to construct a product service system based on existing products to meet the...

In this study, the mechanical properties of isotactic polypropylene (iPP) materials with different crystallinities at room and elevated temperatures were investigated. In order to obtain samples with a certain range of crystallinity, and to ensure a uniform microstructure of these samples, the iPP samples obtained by injection molding required melt...

A thermal analysis method was developed based on heating cell units to study the thermal response of electrical rapid heat cycle molding (ERHCM) molds. Heating efficiency, mold strength and uniformity of temperature distribution on the mold cavity surface were studied as a function of the distance from the center of heating rods to the mold cavity...

The appearance quality of plastic parts in weld lines can be improved significantly through the rapid heating cycle molding (RHCM) process. However, there is no evaluation method for measuring the appearance quality of weld lines to determine whether they are in a good or bad condition. In this study, RHCM parts were molded with electric heating an...

The introduction of gas is the principal difference between external gas-assisted injection molding (EGAIM) and conventional injection molding. In this study, the effects of gas thickness and gas delay time on polymer temperature were discussed. A modified one-dimensional transient heat conduction model of polymer was established to reveal the rela...

Improving existing schemes based on performance goals can have a significant impact on the final product. During the conceptual design stage, the design information is limited and non-numerical, and thus, refinement cannot be performed via existing numerical algorithms. In addition, a conceptual scheme is formed by combining the appropriate princip...

Bismuth ferrite (BiFeO 3 , BFO) submicron cubes and 3D BFO/graphene composite materials were synthesized by a simple hydrothermal process. The crystallization processes of the 3D BFO/graphene composites with different graphene oxide (GO) concentrations were studied for their visible light photocatalytic properties. Compared to the single BFO submic...

The uncertainty information of design variables is included in the available representation data, and there are differences among representation data from different sources. Therefore, the paper proposes a nonparametric uncertainty representation method of design variables with different insufficient data from two sources. The Gaussian interpolatio...

The uncertainty information related to uncertain structural, material and geometric parameters is included in the available input uncertainty data, and there are multiple uncertainty types when only insufficient input data is acquired from experimental or numerical analyses. In this study, an uncertainty analysis method for composite laminated plat...

The robust topology optimization approach with uncertainties of loading magnitude and direction is investigated for continuum structures. The input loadings with uncertain magnitude and direction are decomposed using the second order Taylor series expansions, and then the response of statistical response of compliance is calculated using perturbati...

To improve the heating efficiency and cavity surface temperature uniformity, an optimal design method was developed for the heating system in electrical rapid heat cycle molding mold. First, an electrical rapid heat cycle molding mold was simplified as a single heating cell unit for thermal response analysis based on conformal design theory. Second...

Traditional 3D printing craft's limit in fabricating micro/nanostructures and thermosetting materials makes it hard to be directly applied to the fabrication of triboelectric nanogenerator (TENG), whose performance strongly relies on structures and properties of the used materials. To meet these challenges, polymer tubes (tubular polyethylene (PE)...

In the early conceptual design process, a large number of conceptual schemes can be selected. However, existing studies primarily focused on mapping from the function to the principle solution and then evaluating the principle scheme. Currently, many concept selection methods are used for a small number of feasible schemes, thus not addressing a la...

Passage arrangement design in fin channels is an efficient methodology for the reduction of the thermal deterioration influence of inlet flow maldistribution in multiple-stream plate-fin heat exchangers. In this work, the thermal compensation effects of passage arrangement design under different statistical parameters of inlet flow maldistribution...

Uncertainty quantification accuracy of system performance has an important influence on the results of reliability-based design optimization (RBDO). A new uncertain identification and quantification methodology is proposed considering the strong statistical variables, sparse variables, and interval variables simultaneously. Maximum likelihood funct...

There are differences among sampling data and representation types of uncertain statistical variables, sparse variables and interval variables, which increase the complexity of structure reliability analysis. Therefore, a hybrid first order reliability analysis method considering the three types of uncertain variables is demonstrated in this articl...

An approach for the robust topology optimization (RTO) of continuum structures with loading uncertainty is investigated. The loading uncertainties are quantified using the second order Taylor series expansion of uncertain loading magnitudes and directions, and then the response statistic mean and standard deviation of compliance are calculated usin...

A novel three-dimensional ordered macroporous (3DOM) Cu/Fe3O4 composite film was prepared by electrodepositing ferroferric oxide (Fe3O4) on the 3DOM Cu current collector. Characterizations via electron microscopies and X-ray diffractions confirmed that achieved 3DOM Cu/Fe3O4 composite inherited originally ordered porous structure, but has a layer o...

A ferromagnetic three-dimensional ordered macroporous TiO2/CoPt/α-Fe2O3 (3DOMTCF) nanocomposite was synthesized via a sol-gel approach templated by poly(methyl methacrylate) (PMMA) microspheres. After magnetization, it exhibited an extremely high reversible capacity and a long cycle life, which were ascribed to the internal magnetic field for reusi...

Product design was a repetitive process. Given that product structure was closely related to functions, function change was vital to the final design and core of design change. The effect of predicting function change during conceptual design on the final product structure was important to improve the design quality. A model was proposed to predict...

Rapid heat cycle molding (RHCM) is a special molding process capable of producing molded plastic parts with high surface quality and improved weldline strength and appearance. This study investigated the influence of the weldline on the tensile strength of RHCM and conventional injection molded (CIM) components. The test specimens with and without...

The crystallization and orientation of isotactic polypropylene (iPP) molded by rapid heat cycle molding (RHCM) and conventional injection molding (CIM) were studied. Due to the varying cooling rates and shearing, the molded parts exhibited a multilayered structure (skin, shear and core) across the part thickness, reflecting different degrees of cry...

The functional structure information of a design history is analyzed to capture product design intent information, which is significantly important for the rapid and efficient solving of local demand-varying designs. Based on the intent capture and reuse issues of the design histories of existing products, this study proposes the use of the effectu...

Fiber-reinforced plastics exhibit many merits and injection molding is one of the most common method for the production of plastics. Therefore, injection-molded fiber-reinforced plastic products have been widely used and their properties and structure were studied in the present work. The influences of fiber type, fiber content, and processing on t...

Performance of the rapid heat cycle-molded products is highly correlated to its multilayer structure and crystal form in the multilayers. In this study, isotactic polypropylene was introduced in molding experiments, multi-sites sampling was carried out, and β-crystal contents together with multilayer structure were characterized by scanning electro...

Rapid Heat Cycle Molding is a new environmental-friendly technology to access high surface quality of plastic products. In this paper, the influence of processing parameters of this technology on weld line of High density polyethylene (HDPE) plastics has been investigated using the orthogonal experiment method. Weld line is evaluated by dE(Euclidea...

External gas-assisted injection molding (EGAIM) technology can be applied to effectively reduce the sink marks generated from the shrinkage of plastic parts. In this paper, the interaction mechanism of gas and melting during the EGAIM stage was discussed. The causes of the sink marks on plastic parts as well as the influence of gas-melting interact...

The skin layer formation is directly related to the surface quality of the plastic produced. However, in Rapid Heat Cycle Molding (RHCM), the formation and movement mechanism of the skin layer is different from that of traditional molding. Therefore, the study on skin layer is of great significance for enriching RHCM theory and obtaining high surfa...

A phenomenological thermodynamic Landau–Devonshire theory is developed to investigate phase diagrams of epitaxial ferroelectric films with out-of-plane misfit strain induced by vertical nanocomposites. The thermodynamic potential of ferroelectric films is obtained based on the boundary conditions of three-dimensional clamping induced by the vertica...