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Resin Flow (resin + flow)
Selected AbstractsBark borer Semanotus japonicus (Col., Cerambycidae) utilization of Japanese cedar Cryptomeria japonica: a delicate balance between a primary and secondary insectJOURNAL OF APPLIED ENTOMOLOGY, Issue 7-8 2000E. Shibata To understand how S. japonicus is affected by host nutrition and resin flow, newly hatched larvae were introduced into stressed cedar trees. Stress was induced by either heavy pruning, stem cutting (i.e. removing the side branches and top of tree), or girdling. Larval mortality due to resin flow in the ,heavy pruning treatment' and the ,stem cutting treatment' tended to be lower than that in the untreated control cedar trees where all larvae were drowned by resin flow. Parasitism to the larval stage was observed in the stem-cutting trees, not in living trees, suggesting that S. japonicus may avoid parasitism in living cedar trees because few volatiles are produced. In the ,stem-girdling treatment', although more than 90% of the introduced larvae died due to poor nutrition below the girdle, 7.8% of the larvae above the girdle reached the adult stage. The live body weight of the adults collected from above the girdle was similar to those taken from naturally infested cedar trees. These results suggest that S. japonicus requires adequate host nutrition but that larvae are defenceless against high resin flow. Thus, S. japonicus seems to be in a transition state between being primary or secondary with respect to its attack behavior on living cedar trees. [source] Reactive mold filling in resin transfer molding processes with edge effectsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009Yanyu Ding Abstract Reactive mold filling is one of the important stages in resin transfer molding processes, in which resin curing and edge effects are important characteristics. On the basis of previous work, volume-averaging momentum equations involving viscous and inertia terms were adopted to describe the resin flow in fiber preform, and modified governing equations derived from the Navier,Stokes equations are introduced to describe the resin flow in the edge channel. A dual-Arrhenius viscosity model is newly introduced to describe the chemorheological behavior of a modified bismaleimide resin. The influence of the curing reaction and processing parameters on the resin flow patterns was investigated. The results indicate that, under constant-flow velocity conditions, the curing reaction caused an obvious increase in the injection pressure and its influencing degree was greater with increasing resin temperature or preform permeability. Both a small change in the resin viscosity and the alteration of the injection flow velocity hardly affected the resin flow front. However, the variation of the preform permeability caused an obvious shape change in the resin flow front. The simulated results were in agreement with the experimental results. This study was helpful for optimizing the reactive mold-filling conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Closed form solution of resin flow from multiple line gates in liquid composite moldingPOLYMER COMPOSITES, Issue 8 2010B. Markicevic The resin flow from multiple line injection into a fibrous porous medium is investigated analytically and experimentally. The flow in a rectangular porous medium is created by placing two inlets: a channel along one of the domain edges, and a manifold placed in the center of the domain perpendicular to the first inlet on the top surface of the porous medium. It is demonstrated that two distinct sub-regions of the porous medium exist: inner sub-region which is filled by the liquid from the manifold, and outer sub-region that is filled by fluid from the channel. In the experiments, the following geometric parameters are varied: channel cross-sectional area, mold width, and thickness to investigate how the processing parameters influence which part of the overall domain is filled by fluid from a specific inlet. Neither fluid nor porous medium are varied throughout the study. For nonconstrained flow, an analytical model is formulated to predict the interface between the two sub-regions which is called the inner sub-region thickness. Both, implicit and explicit solutions are found, where the explicit solution is represented as inverse Lambert function. The solution relies on one physical constant which is a function of the pressure gradients and the directional permeabilities of the fibrous preform. Comparisons between experimental and analytical results reveal an excellent agreement for various sets of geometric parameters. This research should prove useful in understanding the flow in composites manufacturing when resin is injected simultaneously from multiple gates and channels. POLYM. COMPOS., 31:1434,1441, 2010. © 2009 Society of Plastics Engineers [source] Modeling and analysis of thickness gradient and variations in vacuum-assisted resin transfer molding processPOLYMER COMPOSITES, Issue 5 2008Jing Li As vacuum-assisted resin transfer molding (VARTM) is being increasingly used in aerospace applications, the thickness gradient and variation issues are gaining more attention. Typically, thickness gradient and variations result from the infusion pressure gradient during the process and material variations. Pressure gradient is the driving force for resin flow and the main source of thickness variation. After infusion, an amount of pressure gradient is frozen into the preform, which primarily contributes to the thickness variation. This study investigates the mechanism of the thickness variation dynamic change during the infusion and relaxing/curing processes. A numerical model was developed to track the thickness change of the bagging film free surface. A time-dependent permeability model as a function of compaction pressure was incorporated into an existing resin transfer molding (RTM) code for obtaining the initial conditions for relaxing/curing process. Control volume (CV) and volume of fluid (VOF) methods were combined to solve the free surface problem. Experiments were conducted to verify the simulation results. The proposed model was illustrated with a relatively complex part. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Simulation and validation of resin flow during manufacturing of composite panels containing embedded impermeable inserts with the VARTM processPOLYMER COMPOSITES, Issue 4 2007Jeffrey M. Lawrence Modern composite materials are becoming more and more advanced as engineers are better able to take advantage of their properties. In addition to their lighter weight and net-shape manufacturing, current interest is to make these materials multifunctional. This may require one to insert various objects into the composite to achieve a variety of different goals. It is important to understand how these embedded objects will affect both the manufacturing and the structural integrity of the component. In this work, the effects of impermeable embedded inserts on the infusion stage of vacuum-assisted resin transfer molding (VARTM) will be explored. In VARTM, one places a distribution media on top of the preform to aid the filling as the resin will first fill the face of the preform in contact with the distribution media and will then infuse the preform in the thickness direction. However, if one has an embedded impermeable insert in the thickness direction, it will obstruct the flow in the region below the embedded object. Several case studies are conducted to understand the effect of the geometry and placement of the embedded insert and the distribution media lay out and properties on the impregnation of the resin into the fiber preform. Finally, an approach is outlined to modify the layout of the distribution media in order to ensure a complete saturation of the preform under all but the most extreme conditions. The approach is validated with experiments. POLYM. COMPOS., 28:442,450, 2007. © 2007 Society of Plastics Engineers [source] Flow modeling and simulation for vacuum assisted resin transfer molding process with the equivalent permeability methodPOLYMER COMPOSITES, Issue 2 2004Renliang Chen Vacuum assisted resin transfer molding (VARTM) offers numerous advantages over traditional resin transfer molding, such as lower tooling costs, shorter mold filling time and better scalability for large structures. In the VARTM process, complete filling of the mold with adequate wet-out of the fibrous preform has a critical impact on the process efficiency and product quality. Simulation is a powerful tool for understanding the resin flow in the VARTM process. However, conventional three-dimensional Control Volume/Finite Element Method (CV/FEM) based simulation models often require extensive computations, and their application to process modeling of large part fabrication is limited. This paper introduces a new approach to model the flow in the VARTM process based on the concept of equivalent permeability to significantly reduce computation time for VARTM flow simulation of large parts. The equivalent permeability model of high permeable medium (HPM) proposed in the study can significantly increase convergence efficiency of simulation by properly adjusting the aspect ratio of HPM elements. The equivalent permeability model of flow channel can simplify the computational model of the CV/FEM simulation for VARTM processes. This new modeling technique was validated by the results from conventional 3D computational methods and experiments. The model was further validated with a case study of an automobile hood component fabrication. The flow simulation results of the equivalent permeability models were in agreement with those from experiments. The results indicate that the computational time required by this new approach was greatly reduced compared to that by the conventional 3D CV/FEM simulation model, while maintaining the accuracy, of filling time and flow pattern. This approach makes the flow simulation of large VARTM parts with 3D CV/FEM method computationally feasible and may help broaden the application base of the process simulation. Polym. Compos. 25:146,164, 2004. © 2004 Society of Plastics Engineers. [source] Flow front measurements and model validation in the vacuum assisted resin transfer molding processPOLYMER COMPOSITES, Issue 4 2001R. Mathuw Through-thickness measurements were recorded to experimentally investigate the through thickness flow and to validate a closed form solution of the resin flow during the vacuum assisted resin transfer molding process (VARFM). During the VART'M process, a highly permeable distribution medium is incorporated into the preform as a surface layer and resin is inftised Into the mold, under vacuum. During Infusion, the resin flaws preferentially across the surface and simultaneously through the thickness of the preform, giving rise to a three dimensional-flow front. The time to fill the mold and the shape of the flow front, which plays a key role in dry spot formation, are critical for the optimal manufacture of large composite parts. An analytical model predicts the flow times and flow front shapes as a function of the properties of the preform, distribution media and resin. It was found that the flow front profile reaches a parabolic steady state shape and the length of the region saturated by resin is proportional to the square root of the time elapsed. Experimental measurements of the flow front in the process were carried out using embedded sensors to detect the flow of resin through the thickness of the preform layer and the progression of flow along the length of the part. The time to fill the part, the length of flow front and its shapes show good agreement between experiments and the analytical model. The experimental study demonstrates the need for control and optimization of resin injection during the manufacture of large parts by VARTM. [source] | ||||||||||