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AlN, with its ultra-wide bandgap, is highly attractive for modern applications in deep ultraviolet light-emitting diodes and electronic devices. In this study, the surface and cross-sectional properties of AlN films grown on flat and nano-patterned sapphire substrates are characterized by a variety of techniques, including photoluminescence spectroscopy, high-resolution X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and Raman spectroscopy. The results indicate that different sapphire substrates have minimal impact on the photoluminescence spectrum of the epitaxial films. As the temperature increased, the radius of curvature of the AlN films increased, while the warpage decreased. The AlN films grown on nano-patterned substrates exhibited superior quality with less surface oxidation. During the growth of AlN thin films on different types of substrates, slight shifts in the energy bands occurred due to differences in the introduction of carbon-related impurities and intrinsic defects. The Raman shift and full width at half maximum (FWHM) of the E2(low), A1(TO), E2(high), E1(TO), and E1(LO) phonon modes for the cross-sectional AlN films varied with the depth and temperature. The stress state within the film was precisely determined with specific depths and temperatures. The FWHM of the E2(high) phonon mode suggests that the films grown on nano-patterned substrates exhibited better crystalline quality. [ABSTRACT FROM AUTHOR]

Making molds in the injection molding manufacturing process is one of the basic steps that functions to prevent product defects during the production process. The product defects that most often occur in this manufacturing process include shrinkage and warpage defects. This research will discuss the mold design for the APC SF 11x4.7 propeller product with a twist variation of 45o and minimum shrinkage and warpage values. Glass Fiber Reinforced Polypropylene (GFRPP) will be used as the propeller product material. The entire design process to testing will be carried out using software assistance. The Taguchi method with an L9 orthogonal array matrix (34) was used in this research. where L9 explains that the experiment will be carried out nine times, and 34 means there are three levels and four main factors. The four main factors consist of packing pressure, packing time, melting temperature and injection pressure. The Taguchi method is used with the aim of making it easier to find the variation value that produces the lowest shrinkage and warping defects in the product. The simulation results show that the variation with the smallest shrinkage value produces a value of 7.9% and the variation with the smallest warpage value produces a value of 1.051 mm

Cycloaliphatic epoxides exhibit post‐light irradiation heat‐induced polymerization, creating warp‐resistant green bodies during sintering. However, their use in light polymerization three‐dimensional (3D) printing is limited by slow photo‐curing speeds. In this study, a photo‐cationic polymerizable ceramic slurry was developed for 3D printing by mixing oxetane with cyclo‐aliphatic epoxide. This mixture improved photo‐curing speed, reduced resin viscosity, and enhanced the ceramic slurry's solid content. Additionally, we optimized the slurry by considering the specific and content ratio of photosensitizers and light absorbers. The optimized slurry polymerized unreacted functional groups in the polymer, improving the fracture strength of the green bodies through enhanced crosslinking density and uniformity in each layer. Ultimately, a sintered body without warpage was produced by the improved green bodies. This approach provides a solution related to controlling the photocuring speed and expands the potential applications of 3D printing in areas where the precision and stability of the printing material are required. [ABSTRACT FROM AUTHOR]

Chip bonding, an essential process in power semiconductor device packaging, commonly includes welding and nano-silver sintering. Currently, most of the research on chip bonding technology focuses on the thermal stress analysis of tin–lead solder and nano-silver pressure-assisted sintering, whereas research on the thermal stress analysis of the nano-silver pressureless sintering process is more limited. In this study, the pressureless sintering process of nano-silver was studied using finite element software, with nano-silver as an interconnect material. Using the control variable method, we analyzed the influences of sintering temperature, cooling rate, solder paste thickness, and solder paste area on the residual stress and warping deformation of power devices. In addition, orthogonal experiments were designed to optimize the parameters and determine the optimal combination of the process parameters. The results showed that the maximum residual stress of the module appeared on the connection surface between the power chip and the nano-silver solder paste layer. The module warping deformation was convex warping. The residual stress of the solder layer increased with the increase in sintering temperature and cooling rate. It decreased with the increase in coating thickness. With the increase in the coating area, it showed a wave change. Each parameter influenced the stress of the solder layer in this descending order: sintering temperature, cooling rate, solder paste area, and solder paste thickness. The residual stress of the nano-silver layer was 24.83 MPa under the optimal combination of the process parameters and was reduced by 29.38% compared with the original value of 35.162 MPa. [ABSTRACT FROM AUTHOR]

In practical applications, polyurethane (PU) foam must be rigid to meet the demands of various industries and provide comfort and protection in everyday life. PU foam components are extensively used in structural foam, thermal insulation, decorative panels, packaging, imitation wood, and floral foam, as well as in models and prototypes. Conventional technology for producing PU foam parts often leads to defects such as deformation, short shots, entrapped air, warpage, flash, micro-bubbles, weld lines, and voids. Therefore, the development of rigid PU foam parts has become a crucial research focus in the industry. This study proposes an innovative manufacturing process for producing rigid PU foam parts using silicone rubber molds (SRMs). The deformation of the silicone rubber mold can be predicted based on its wall thickness, following a trend equation with a correlation coefficient of 0.9951. The volume of the PU foam part can also be predicted by the weight of the PU foaming agent, as indicated by a trend equation with a correlation coefficient of 0.9824. The optimal weight ratio of the foaming agent to water, yielding the highest surface hardness, was found to be 5:1. The surface hardness of the PU foam part can also be predicted based on the weight of the water used, according to a proposed prediction equation with a correlation coefficient of 0.7517. The average surface hardness of the fabricated PU foam part has a Shore O hardness value of approximately 75. Foam parts made with 1.5 g of water added to 15 g of a foaming agent have the fewest internal pores, resulting in the densest interior. PU foam parts exhibit excellent mechanical properties when 3 g of water is added to the PU foaming agent, as evidenced by their surface hardness and compressive strength. Using rigid PU foam parts as a backing material in the proposed method can reduce rapid tool production costs by about 62%. Finally, an innovative manufacturing process for creating large SRMs using rigid PU foam parts as backing material is demonstrated. [ABSTRACT FROM AUTHOR]

A semiconductor package is responsible to safeguard the die from the external environment that can affect its performance and reliability. A flip-chip package ensures that the assembly, which is capable of high input-output function, maintains its operation and safeguards the interconnection paths particularly the solder ball deformation and fatigue. In this study, a finite element analysis model of the solder-underfill layers of a flip-chip package was developed and validated by statistical comparison of the warpage and stress from experimental data and theoretical calculations of composite deformation and stress. Quarter modeling reduces the computational load while maintaining sufficient detail that allows for efficient use of computational resources. It is then complemented by the design of experiment which systematically varied the parameters to explore the design space and optimize the configuration. Moreover, the method was able to account for nonlinear effects, especially on the impact of solder content on die stress. This provides a more precise control over the thermo-mechanical behavior of the package which would lead to more informed decisions in designing packages. The results have shown desirability of 0.8491 with an optimal layer thickness setting of 0.06 mm and solder content of 18.1 % in consideration of the nonlinear factor effect of solder content on the die stress.

Warpage deformation is a typical phenomenon for polymer injection-molded parts, mainly caused by unbalanced cooling, and it is inevitable. Complex process parameters usually lead to uncontrollable thermal behavior of the polymer materials during injection molding and significant experimental errors. This work presents an experimental mold with a flat mold cavity and nine local heating sections to determine the exact effect of temperature difference on the thermal deformation of injection molded parts. Through local heating at different positions, different warpage deformation was caused. Experimental results demonstrated the relationship between the local temperature and the local thermal warpage. The predicted results of local temperature distribution by numerical simulation presented a strong negative correlation with the experimental results (R2 = 67%); however, the warpage prediction results by numerical simulation were moderate (R2 = 35%). Machine learning with neural networks was further conducted based on the experimental results. When more data was given with a suitable neural network structure, the model prediction accuracy of warpage could be up to 97%, while for the extrapolation test, the prediction accuracy could also be up to 89%. This local thermal heating technique and neural network modeling method can be applied in further theoretical investigation of warpage of injection molded parts and support the development of new models with high accuracy in predicting warpage deformation. [ABSTRACT FROM AUTHOR]

The finite element method combined with the experiment analyzed the evolution mechanism of the plastic strain state and warping deformation of the TA2/Q345R composite plate during heat treatment. Then, the factors influencing plastic strain state and shape warping in the composite plate were discussed. The results show that during the heat treatment process, the composite plate’s internal strain state and macroscopic shape state are impacted by the thermal strain and bending strain between the heterogeneous metal layers, and both are in a continuous dynamic variation state. Therefore, the ultimate deformation behaviour of the composite plate depends on the accumulation and inheritance of plastic deformation during heat treatment. There is a critical value of the composite ratio and the total thickness of the composite plate, respectively, which determines the direction of the warpage after heat treatment. [ABSTRACT FROM AUTHOR]

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Warpage in semiconductor packages is a critical issue that affects their reliability and performance. This study aims to minimize the warpage of a bi-material dummy package by optimizing the post-mold curing (PMC) temperature profile. A warpage simulation model was developed considering the viscoelastic properties and cure shrinkage behavior of the epoxy molding compound (EMC). A compression molding monitoring system was also developed to analyze the cure behavior of the EMC. The gelation point of the EMC during compression molding was determined using a dielectric sensor, while cure shrinkage behaviors were analyzed using a fiber Bragg grating sensor. Viscoelastic properties were characterized through stress relaxation tests, and thermal properties were measured using three-dimensional digital image correlation. The developed simulation model was used to optimize the PMC temperature profile using a genetic algorithm. Experimental validation showed that the optimized temperature profile reduced the warpage from ∼1519 μm to 486 μm compared to a linear profile. The findings of this study have broader implications for the design and manufacturing of semiconductor packages, as the proposed approach can be applied to minimize warpage and improve package reliability.

AlN, with its ultra-wide bandgap, is highly attractive for modern applications in deep ultraviolet light-emitting diodes and electronic devices. In this study, the surface and cross-sectional properties of AlN films grown on flat and nano-patterned sapphire substrates are characterized by a variety of techniques, including photoluminescence spectroscopy, high-resolution X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and Raman spectroscopy. The results indicate that different sapphire substrates have minimal impact on the photoluminescence spectrum of the epitaxial films. As the temperature increased, the radius of curvature of the AlN films increased, while the warpage decreased. The AlN films grown on nano-patterned substrates exhibited superior quality with less surface oxidation. During the growth of AlN thin films on different types of substrates, slight shifts in the energy bands occurred due to differences in the introduction of carbon-related impurities and intrinsic defects. The Raman shift and full width at half maximum (FWHM) of the E2(low), A1(TO), E2(high), E1(TO), and E1(LO) phonon modes for the cross-sectional AlN films varied with the depth and temperature. The stress state within the film was precisely determined with specific depths and temperatures. The FWHM of the E2(high) phonon mode suggests that the films grown on nano-patterned substrates exhibited better crystalline quality.

The thermal balance of injection molds is defined by the cooling channel layout. However, the fluid tempering of injection molds underlies certain restrictions concerning the thermal dynamic and the local limitation of the zone of influence. The optimal heat balance within the mold to minimize warpage cannot be solely achieved with conformal cooling channels. Ceramic heating coating systems applied by Thermal Spraying on the cavity wall are a novel tempering method for high heating rates and offer the possibility of a more local heat input. In terms of the thermal mold design, the position and size of local heating coating systems need to be determined. A methodology is proposed, which connects the optimization of part warpage by defining the necessary local heat flux within the mold with the determination of the heating coating placement. Due to the dependence of the coating placement on the heating time and the power, different decision criteria of these parameters are discussed with regard to the process efficiency. The developed methodology can calculate the necessary heating power distribution to homogenize the surface temperature and freeze time. A second step discretizes the heating power distribution to certain manufacturable heating zones. [ABSTRACT FROM AUTHOR]

Double‐injection molding involves the use of two injection units, A and B, which can combine two different plastics into one part in a single injection molding process. Double‐injection molding can promote the recycling of plastic waste as well as improve the performance and dull appearance of plastic products made from recycled materials. However, the warpage of parts is a significant challenge in double‐injection molding. Warpage is significantly affected by the properties of the recycled material and injection molding process. In this study, the relationship between the warpage of double‐injection‐molded parts using raw and recycled materials was studied through uniform design experiments. To investigate the processes and warpage, the material was recycled several times, and its properties were tested. A regression model was established to describe the quantitative relationship between the important parameters and warpage. The number‐average molecular weight and weight‐average molecular weight exhibited the largest decrease after the first recycling cycle with a 21.11% and 41.11% decrease, respectively. The melting temperature decreased from 164.61 to 159.35°C, and the crystallinity did not change significantly. The processing parameters varied with the change in the properties of PP recycled materials, with the melt temperature decreased from 225 to 210°C. In addition, the number of recycling cycles and holding time for B were the most important factors influencing the warpage of double‐injection‐molded parts, followed by holding time for A and melt temperature for A. Warpage can be reduced by increasing holding times B and A. The experimental results provide important data for reducing the warpage of double‐injection‐molded parts with recycled materials. Highlights: Double‐injection‐molded parts containing recycled materials were prepared.Recycling enhanced the filling capacity of polypropylene.The regression model of warpage with variables was established.Warpage can be improved by adjusting processes and materials. [ABSTRACT FROM AUTHOR]

The food industry holds immense promise for 3D printing technology. Current research focuses mainly on optimizing food material composition, molding characteristics, and printing parameters. However, there is a notable lack of comprehensive studies on the shape changes of food products, especially in modeling and simulating deformations. This study addresses this gap by conducting a detailed simulation of the starch gel printing and deformation process using COMSOL Multiphysics 6.2 software. Additive manufacturing (AM) technology is widely acclaimed for its user-friendly operation and cost-effectiveness. The 3D printing process may lead to changes in part dimensions and mechanical properties, attributable to the accumulation of residual stresses. Studies require a significant amount of time and effort to discover the optimal composition of the printed material and the most effective deformed 3D structure. There is a risk of failure, which can lead to wasted resources and research delays. To tackle this issue, this study thoroughly analyzes the physical properties of the gel material through COMSOL Multiphysics 6.2 software, It simulates the heat distribution during the 3D printing process, providing important insights into how materials melt and solidify. Three-part models with varying aspect ratios were meticulously designed to explore shape changes during both the printing process and exposure to an 80 °C environment, employing NMR and rheological characterization. Using the generalized Maxwell model for material simulation in COMSOL Multiphysics, the study predicted stress and deformation of the parts by analyzing solid heat transfer and solid mechanics physical fields. Simulation results showed that among three models utilizing a gel-PET plastic membrane bilayer structure, Model No. 1, with the largest aspect ratio, exhibited the most favorable deformation under an 80 °C baking environment. It displayed uniform bending in the transverse direction without significant excess warpage in the edge direction. In contrast, Models No. 2 and No. 3 showed varying degrees of excess warpage at the edges, with Model No. 3 exhibiting a more pronounced warpage. These findings closely aligned with the actual printing outcomes. [ABSTRACT FROM AUTHOR]

There are multiple factors that contribute to the warpage problems where molten part is distorted during solidification in rotational molding. A novel warpage simulation model is developed accounting for the effect of various process parameters like crystallinity change, temperature‐dependent polymer properties, and cooling rate. The polymer material properties were readily not available; they were constructed from literature data with adaptation to the process condition and their significance on simulation results is discussed in detail. A systematic detailed simulation analysis of warpage in box part was done and results were compared with experimental values published in literature. The warpage magnitude under seven different cooling methods are presented. It was found that externally water cooled parts exhibited maximum warpage which is also corroborated by literature data while the parts cooled by water on either sides of the part show reduction in warpage. The warpage simulation results show an agreement with deviation ranging from 1.2% to 69% with experimental values. Highlights: A novel thermal expansion coefficient approach was adopted for the first time to develop warpage simulation of rotationally moulded parts.Inclusion of temperature‐dependent thermo‐mechanical properties of polymer in the simulation model.The cooling rate is directly proportional to the warpage in the parts.Validating warpage simulation results for seven different cooling methods with experimental measurements.Maximum warpage is seen where the highest temperature difference exists between part and mould. [ABSTRACT FROM AUTHOR]

We discuss a technique for investigating changes in complex topography and shape of structures using geomorphometric methods to study surfaces of wafers and membranes formed by the Bosch process. The wafers were analyzed before and after the deposition of the SiO2 layer. The membranes were analyzed during the bulge testing. The study was carried out using maps of the catchment area and principal curvatures taking into account artifacts of the approximation of experimental data. We found a correspondence between the distribution of lines connecting the highest surface areas before and after the deposition of the SiO2 layer on the wafers. For membranes with structure: Al(0.8 μm)/SiO2(0.6 μm)/Al(1.1 μm), pSi*(0.8 μm)/SiNx (0.13 μm)/SiO2, Al(0.6 μm) we also found that features of membrane boundaries are mainly caused by their initial shape rather than change under the action of an applied pressure. The advantages of geomorphometric methods for studying changes in the shape of wafers and thin-film membranes in technological processes for the manufacturing of microelectronic devices are shown in comparison with traditional methods for analyzing surface topography maps. [ABSTRACT FROM AUTHOR]

Material extrusion (MEX) continues to be a pivotal additive manufacturing (AM) process, involving the selective heating and layer-by-layer deposition of material. However, conventional finite-element models (finite-element analysis) face limitations in accurately simulating the MEX process, highlighting the need for experimental validation. This paper highlights an advanced material modeling technology that streamlines the development of composite parts using large format AM (LFAM). It specifically focuses on a thermoplastic acrylonitrile butadiene styrene (ABS) matrix composite material enriched with 20% short carbon fibers. The study employs integrated computational materials engineering, integrating (i) the manufacturing process, (ii) the material's microstructure, (iii) homogenization techniques, and (iv) the performance of the final part. The development of a digital twin for pellet extrusion is proposed, emphasizing the importance of micro-structure characterization to account for warpage and residual stresses that lead to part distortion. The demonstrator manufactured for this study is a wind turbine mold of a blade section. Experimental tests revealed an elastic modulus of 5.5 GPa and a hardening modulus of 2.4 GPa for the composite. The numerical microscopic model showed a 16% error in the elastic modulus compared to experimental results. The study concludes that the homogenization techniques are effective in predicting the elastic properties but lack accuracy in the plastic region. The application of the model to the LFAM process of pellet extrusion is demonstrated, with simulation results showing a maximum deformation close to the center of the wind turbine blade mold. [ABSTRACT FROM AUTHOR]

When the dissimilar metal composite plate accumulates inconsistent deformation to a certain degree during the heat treatment process, it indicates bad plate morphology such as warpage. Therefore, it is crucial to explore the mechanism of coordinated deformation between layers under thermal–mechanical coupling during heat treatment. This study investigates the interlayer coordinated deformation mechanism of the stainless-steel clad plate (304/Q235 stainless-steel clad plate) under thermal–mechanical coupling by using three heat treatment methods: rapid cooling process, rapid cooling in the high-temperature stage + slow cooling in the low-temperature stage, and rapid cooling + tempering process. And this study enlightens that the temperature field distribution and the longitudinal stress–strain distribution are obtained by using the Abaqus software. The effects of different tensile and thickness ratios on the residual stress are analyzed. The final experiment found that the maximum longitudinal stress and plastic strain appear on the upper and lower surfaces during heat treatment. The rapid cooling heat treatment process has light warpage and good shape. When the thickness ratio of the composite plate is 1:4, the warpage is the lightest. The increase of set tension will increase the compressive stress value in the residual stress. In contrast, the tensile stress value will decrease. [ABSTRACT FROM AUTHOR]

We investigate the microstructural evolution of electrochemically deposited poly-crystalline Cu films during subsequent thermal process cycles at mild maximum temperatures, compatible with the integration in advanced metallization schemes for electronic device manufacturing. The modifications induced by the thermal budget have been characterized at different scales (from the film-substrate interface to the wafer scale) with different complementary techniques: X-ray Diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and dynamical warpage measurements. Moreover, the film internal grains' evolution has been modelled by a tri-dimensional on-cell model, derived by the Pott-like multi-states configurational energy dependence, able to consider multiple orientation of the grains and densification kinetics in the canonical ensemble. Finally, a macroscopic model of the warpage dependence on the process conditions is discussed. The presented joint theoretical and experimental analysis provides a complete and consistent scenario of the grain densification phenomenon and its impact for the Cu film microstructure and the composite system morphology, indicating several strategies for the integration of the process in real device structures. [ABSTRACT FROM AUTHOR]

The paper considers the main types and causes of surface damage that lead to the destruction and failure of large-sized bearings of motor-wheel reducers (MWR) of BELAZ mining dump trucks. The disadvantages of 20Х2Н4A (20Kh2N4A) steel currently used for the manufacture of large-sized MWR bearings are given. It is shown that using this steel it is problematic to achieve a high and uniform distribution of microhardness values over the thickness of the hardened layer. The analysis of the destruction of this type of bearings made of 20Kh2N4A steel largely determining the required life of the motor-wheel reducers, is carried out. The obtained research results indicate the need to use new grades of steels for the manufacture of largesized MWR bearings.

Chip bonding, an essential process in power semiconductor device packaging, commonly includes welding and nano-silver sintering. Currently, most of the research on chip bonding technology focuses on the thermal stress analysis of tin–lead solder and nano-silver pressure-assisted sintering, whereas research on the thermal stress analysis of the nano-silver pressureless sintering process is more limited. In this study, the pressureless sintering process of nano-silver was studied using finite element software, with nano-silver as an interconnect material. Using the control variable method, we analyzed the influences of sintering temperature, cooling rate, solder paste thickness, and solder paste area on the residual stress and warping deformation of power devices. In addition, orthogonal experiments were designed to optimize the parameters and determine the optimal combination of the process parameters. The results showed that the maximum residual stress of the module appeared on the connection surface between the power chip and the nano-silver solder paste layer. The module warping deformation was convex warping. The residual stress of the solder layer increased with the increase in sintering temperature and cooling rate. It decreased with the increase in coating thickness. With the increase in the coating area, it showed a wave change. Each parameter influenced the stress of the solder layer in this descending order: sintering temperature, cooling rate, solder paste area, and solder paste thickness. The residual stress of the nano-silver layer was 24.83 MPa under the optimal combination of the process parameters and was reduced by 29.38% compared with the original value of 35.162 MPa.

Warpage is one of the prominent issues in Fused Filament Fabrication. The cause of this is the rapid cooling of the polymer during extrusion. The residual thermal stresses accumulated within the print part result in a shape distortion and subsequent detachment of the object from the print bed. In this study, both experimental and numerical approaches were used to identify the stresses due to thermal shrinking that occurs in soft polymers such as wax. A temperature sweep test was performed using a rotational rheometer to measure the magnitude of axial forces that are generated due to the thermal shrinking of a thin layer of 3D printable wax. The thermal stresses responsible for warpage were computed analytically and using the FEA. It was found that due to thermal processes, the stress magnitude can reach a value of 1.17 MPa. This value is enough to cause the plastic deformation in the wax part having a thin elongated shape. In addition, Taguchi's robust design has identified two major FFF parameters that impact the warpage in amorphous soft polymers. They are the printing speed and the print bed temperature. To achieve a low level of warpage, it is important to make sure that the layer deposition occurs at medium speeds and the print bed temperature is moderately high according to the findings of this study. [ABSTRACT FROM AUTHOR]

Analyses in the present work focus on understanding the influence of the WAAM (wire arc additive manufacturing) deposition pattern and travel speed on residual stress and warpage in aluminum alloy. The thermal profiles are analyzed using thermomechanical FE simulations. Analysis shows that the out–in deposition pattern leads to the highest level of residual stress and warpage. It is also found that an increase in the travel speed decreases the peak temperature and thermal gradient during the AM deposition, which results in a lower level of residual stress generation. A comparison of results for the line-type patterns (raster and alternate) suggests that the deposition interval between each deposition has little influence on thermal profiles, residual stress generation, and warpage. However, the contour-type patterns significantly affect the heat transfer, thermal gradient, and cooling rate during the AM deposition. [ABSTRACT FROM AUTHOR]

Injection molding (IM) is an ideal technique for the low-cost mass production of moderately thick plane lenses (MTPLs). However, the optical performance of injection molded MTPL is seriously degraded by the warpage and sink marks induced during the molding process with complex historical thermal field changes. Thus, it is essential that the processing parameters utilized in the molding process are properly assigned. And the challenges are further compounded when considering the MTPL molding energy consumption. This paper presents a set of procedures for the optimization of injection molding process parameters, with warpage, sink marks reflecting the optical performance, and clamping force reflecting the molding energy consumption as the optimization objectives. First, the orthogonal experiment was carried out with the Taguchi method, and the S/N response shows that these three objectives cannot reach the optimal values simultaneously. Second, considering the experimental data scale, the back propagation neural network updated by the particle swarm optimization method (PSO-BPNN) was applied to establish the complex nonlinear mapping relationship between the process parameters and these three trade-off objectives respectively. Then, the Pareto optimal frontier of the multi-objective optimization problem was attained by multi-objective particle swarm optimization using a mutation operator and dominance coefficient algorithm (OMOPSO). And the competitive relationship between these objectives was further confirmed by the corresponding pairwise Pareto frontiers. Additionally, the TOPSIS method with equal weights was employed to achieve the best optimal solution from the Pareto optimal frontier. The simulation results yielded that the maximum values of warpage, sink marks, and clamping force could be reduced by 7.44%, 40.56%, and 5.56%, respectively, after optimization. Finally, MTPL products were successfully fabricated. [ABSTRACT FROM AUTHOR]

In this paper, the influence of different cooling processes on the stress, strain and shape warping of low carbon bainite steel Q690D during laminar cooling is analyzed, and a temperature stress–strain coupled finite element model of low carbon bainite steel Q690D is established. For the warping deformation of medium and thick plates, edge shielding, symmetrical cooling of upper and lower surfaces and head shielding are adopted for their length, width and thickness. The results show that when using edge occlusion, the best occlusion distance is 0.1 m; when the upper and lower surfaces are symmetrically cooled, the stress symmetry is basically realized; when head shielding is used, the best masking distance is 0.2 m. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the process of preparing textile composites by resin transfer molding (RTM) method, both the upper and lower surface of the mold will interact with the composite parts due to the mismatch of thermal expansion coefficient between the mold and the part, resulting in warpage deformation. To address this key technical problem, this article first studied the effect of mold on the warpage deformation of composite material under different fiber volume fractions. Then a mold–part interaction modeling method for RTM process with nonthermoelastic deformation is proposed. By introducing shear layers between the upper and lower surfaces of the mold and the composite part, a finite element simulation model for predicting the curing deformation of the component is established and experimentally verified. The results show that the effect of mold–part interaction on the warpage deformation of the composite decreases with increasing fiber volume fraction. Meanwhile, the proposed modeling method can avoid complete material characterization, and the comparison between experimental and simulation results proves that the model can accurately simulate the curing deformation of composite components under the same process conditions. Finally, the analysis reveals that the interaction caused by thermal mismatch between the composites and the mold is less related to the intermediate layup, but mainly related to the fiber orientation of the layup layer in contact with the mold. Highlights: The warpage deformation law of the mold on the composites with different fiber volume fractions is investigated.A mold–part interaction modeling method for a resin transfer molding process with nonthermoelastic deformation is proposed, where the mold stretching effect is represented by the cumulative effect of the interaction between the two layers on the upper and lower surfaces of the part. [ABSTRACT FROM AUTHOR]

The high crystallinity and fast crystallization rate of polypropylene (PP) often result in severe warpage of final parts prepared by means of material extrusion additive manufacturing (MEAM). In this work, the effect of bed temperature (Tb) and nozzle temperature (Tn) on the dimensional accuracy and mechanical property of MEAM‐printed PP copolymer parts was investigated. It is found that raising Tb and Tn could significantly reduce the warpage of PP parts by regulating the crystallization behavior of PP. Specially, the amount of γ‐crystal grows obviously while the total crystallinity remains unchanged, as Tb or Tn increases. Moreover, the more the content of γ‐crystal, the lower the warpage height of PP samples is. Hence, a close correlation between the content of γ‐crystal and part deformation of MEAM‐printed PP parts is successfully established. This is mainly related to the large rigidity of γ‐crystal, which significantly reduces the volume shrinkage of PP during MEAM process. Besides, the raise of Tb or Tn also enhances the tensile strength, modulus and the elongation at break of PP parts. This wok provides an effective and convenient method for the manufacture of PP parts with good dimensional accuracy and excellent mechanical properties by means of MEAM techniques. [ABSTRACT FROM AUTHOR]