Making costly manufacturing smart with transfer learning under limited data: A case study on composites autoclave processing

The integration of advanced manufacturing processes with ground-breaking Artificial Intelligence methods continue to provide unprecedented opportunities towards modern cyber-physical manufacturing processes, known as smart manufacturing or Industry 4.0. However, the “smartness” level of such approaches closely depends on the degree to which the implemented predictive models can handle uncertainties and production data shifts in the factory over time. In the case of change in a manufacturing process configuration with no sufficient new data, conventional Machine Learning (ML) models often tend to perform poorly. In this article, a transfer learning (TL) framework is proposed to tackle the aforementioned issue in modeling smart manufacturing. Namely, the proposed TL framework is able to adapt to probable shifts in the production process design and deliver accurate predictions without the need to re-train the model. Armed with sequential unfreezing and early stopping methods, the model demonstrated the ability to avoid catastrophic forgetting in the presence of severely limited data. Through the exemplified industry-focused case study on autoclave composite processing, the model yielded a drastic (88%) improvement in the generalization accuracy compared to the conventional learning, while reducing the computational and temporal cost by 56%.     

使用PVB膜片作为安全玻璃夹层的常见问题与改进方法

研究了聚乙烯醇缩丁醛（PVB）膜片、浮法玻璃和夹玻工艺对夹层安全玻璃的影响,探讨夹玻的各个工序中出现不正常的原因,并提出解决问题的应对方法,提高了最终制品的质量,实现夹玻的科学生产.     

渗碳体高温高压金刚石化的显微分析

片状触媒合成金刚石有一个重要现象：金刚石总包覆着一层很薄的金属膜，金属包膜在金冈4石的生长过程中起着重要作用。本文利用扫描电镜（SEM）、X射线衍射仪（XRD）和透射电镜（TEM）研究了金属包膜的组织形貌、相结构组成和微观结构。通过研究金属包膜，探讨金刚石相交合成机理，进而优化合成工艺。结果表明：渗碳体在高温高压作用下发生金刚石化，形成金刚石单晶；同时当铁基金属包膜内的渗碳体分布较均匀时金刚石单晶的晶形较完整，反之则晶形较差。     

Thermal press curing of advanced thermoset composite laminate parts

An alternative process to autoclaving, called Thermal Press Curing (TPC), is proposed, whereby an uncured composite laminate is pressed between a heated curing mold and customized rubber-faced mold that are designed to provide uniform temperature and pressure conditions. TPC was demonstrated by designing a complex 3-D ‘benchmark’ part shape, applying a simple computational algorithm to derive the required tool shapes, and fabricating the tooling. A comparative study was performed involving the benchmark part made from four plies of woven carbon/epoxy prepreg material. Identical laminates were pre-formed by double diaphragm forming and then cured and consolidated by autoclaving, Quickstep, and TPC using standard industry practice. Results of the study indicate that the TPC part is of similar quality as compared to those made by autoclaving and Quickstep, but, more importantly, requiring significantly less energy and resource consumption, lower cost (capital and recurring), and less preparation and cycle time.     

Evaluation of bending strain measurements in a composite sailboat bowsprit with embedded fibre Bragg gratings

Acrylate-coated Fibre Bragg Gratings (FBGs) were embedded in a sailing boat bowsprit tubular section manufactured using the vacuum bagging process in autoclave with the aim of measuring strains under realistic loading conditions. In order to establish an effective procedure for sensor integration, flat tensile specimens with embedded sensors were firstly produced under different processing conditions, using advanced composite material employed in the marine industry. Information obtained in this way was used to manufacture a sailboat bowsprit with an array of gratings embedded between the last inner plies. In order to assess the sensitivity and accuracy of the embedded sensors, the bowsprit was subjected to bending tests and the results were compared to analytical values and to data obtained from electrical strain gages. Results are very encouraging but reveal that great attention must be paid both to the integration process and to the in situ calibration of the embedded sensors.     

Low-energy electron beam cured tape placement for out-of-autoclave fabrication of advanced polymer composites

The autoclave curing process for advanced polymer composites is labor and capital intensive, with the curing cost increasing dramatically by the growth in part size. In order to develop an out-of-autoclave (OOA) fabrication process for advanced polymer composites, a new process integrating automated tape placement with low-energy electron beam radiation curing was explored, by which in situ layer-wise curing of advanced composites can be achieved with the tape placement process. The irradiation process was optimized to get a homogenous curing, by tuning the electron beam dose-depth distribution in the prepreg material. Besides, the curing characteristics of the prepreg material by the low-energy electron beam irradiation was investigated and effect of exposure dose and post curing on curing degree, glass transition temperature (Tg) and interlaminar shear strength (ILSS) were characterized experimentally.     

Mechanical activation-assisted autoclave processing and sintering of HfB2-HfO2 ceramic powders

This study reports on the synthesis and consolidation of HfB₂-HfO₂ ceramic powders via mechanical activation-assisted autoclave processing followed by pressureless sintering (PS) or spark plasma sintering (SPS). HfCl₄, B₂O₃ and Mg starting powders were mechanically activated for 5 min to obtain homogeneously blended precursors with active particle surfaces. Autoclave synthesis was carried out at a relatively low temperature at 500 °C for 6 or 12 h. As-synthesized powders were purified from reaction by-products such as MgO and MgCl₂ by washing and acid leaching treatments. The characterization investigations of the as-synthesized and purified powders were performed by using an X-ray diffractometer (XRD), stereomicroscope (SM), scanning electron microscope (SEM) and particle size analyzer (PSA). The purified powders with an average particle size of about 190 nm comprised the HfB₂ phase with an amount of 79.6 wt% in addition to the HfO₂ phase and a very small amount of Mg₂Hf₅O₁₂ phase after mechanical activation for 5 min and autoclave processing for 12 h. They were consolidated at 1700 °C both by PS for 6 h and SPS for 15 min. The Mg₂Hf₅O₁₂ phase decomposed during sintering and bulk samples only had the HfB₂ and HfO₂ phases. The bulk properties of the sintered samples were characterized in terms of microstructure, density, microhardness and wear characteristics. The HfB₂-HfO₂ ceramics consolidated by PS exhibited poor densification rates. A considerable improvement was obtained in the relative density (~91%), microhardness (~16 GPa) and relative wear resistance (2.5) values of the HfB₂-HfO₂ ceramics consolidated by SPS.     

环境友好型无铬高温高压水基钻井液的应用研究

介绍了一种环境友好型高温高压水基钻井液体系,该体系使用新型无铬合成聚合物,具有稳定的高温流变性,能有效控制钻井液高温高压滤失量、防止钻井液高温胶凝。现场应用结果表明,基于新型无铬合成聚合物的高温高压水基钻井液配方具有良好的灵活性,可用于开发适用于不同要求的环境友好型高温高压水基钻井液体系。     

直硝高压釜损坏原因分析及改进设想

介质内氧化性物质的腐蚀性及釜内外压差与外压失稳等是造成直硝高压釜损坏的直接原因 ,提出了相应改进方案     

电子压力计保护装置的研制和试验

高温高压井的射孔-测试联作中,易损坏昂贵的井下电子压力计。针对井下实际情况,研制了一种新的井下电子压力计的保护装置,其具有良好减震性能,并能降低射孔瞬间突然增压对压力计探头的冲击作用。该装置经过现场试验,效果良好。