Numerical Prediction Of Curing And Process Induced Distortion Of Composite Structures
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Author | : Bernath, Alexander |
Publisher | : KIT Scientific Publishing |
Total Pages | : 294 |
Release | : 2021-10-29 |
Genre | : Technology & Engineering |
ISBN | : 3731510634 |
Fiber-reinforced materials offer a huge potential for lightweight design of load-bearing structures. However, high-volume production of such parts is still a challenge in terms of cost efficiency and competitiveness. Numerical process simulation can be used to analyze underlying mechanisms and to find a suitable process design. In this study, the curing process of the resin is investigated with regard to its influence on RTM mold filling and process-induced distortion.
Author | : Neoklis Traiforos |
Publisher | : |
Total Pages | : 0 |
Release | : 2023 |
Genre | : |
ISBN | : |
Author | : Mathias Peter Hartmann |
Publisher | : |
Total Pages | : |
Release | : 2017 |
Genre | : |
ISBN | : 9783843930802 |
Author | : Yean-Der Kuan |
Publisher | : |
Total Pages | : 326 |
Release | : 2000 |
Genre | : Fibrous composites |
ISBN | : |
Woven fiber composites made by resin transfer molding process are currently used as the primary and secondary load bearing structures in automotive and aircraft industries. A variety of defects could be evolved during the injection stage and the curing stage of the process. Improper injection conditions or unsound tool design would result in process induced damage in the form of dry spots, incomplete filling, or displacement of the fiber. In the curing stage, the process parameters of heating and cooling rates, and the temperature level at each element of the curing cycle have direct effects on the development of internal residual stresses, and shape distortion due to warpage. The work in this dissertation aims at developing numerical models to predict, characterize, and minimize process-induced damage during both the injection stage and curing stage in RTM process for woven-fiber composites. A control volume technique based on the finite difference method is used to characterize the flow behavior in resin transfer molding (RTM) of composite structures. Resin flow through fiber mats is modeled as a two-phase flow through porous media. Experimental results on flow behavior of EPON 826 epoxy resin into irregular mold cavity with fiberglass mats agree well with the present numerical simulation. Parametric analysis of several case studies using developed model illustrates the effectiveness of the flow model in investigating the flow pattern, mold filling time, dry spots formulation, and pressure distribution inside the mold. A numerical model describing the evolution of process-induced damage during curing in molded composite panels was developed. The effects of thermo-mechanical and thermo-chemical responses of the material on the evolution of damage during resin transfer molding of the panels are quantified. The developed numerical model in conjunction with an optimization module based on Simulated Annealing (SA) scheme form a useful tool for conducting a parametric design analysis for characterization and management of process-induced damage in composite panels. Experimental investigation of resin transfer molding of composite panels made of epoxy resin (EPON 826) and eight-harness graphite fiber mats, indicates that low cure temperature, moderate heating rate and high rate of cooling after cure would minimize damage during curing. Furthermore the experimental measurements are in agreement with the degree of damage predicted by the numerical models and hence verifying the effectiveness of these models. The models and methods developed in the present work are of broader applicability to process design and optimization of resin transfer molding of composite structures.
Author | : Poppe, Christian Timo |
Publisher | : KIT Scientific Publishing |
Total Pages | : 332 |
Release | : 2022-07-18 |
Genre | : Technology & Engineering |
ISBN | : 3731511908 |
Interdisciplinary development approaches for system-efficient lightweight design unite a comprehensive understanding of materials, processes and methods. This applies particularly to continuous fibre-reinforced plastics (CoFRPs), which offer high weight-specific material properties and enable load path-optimised designs. This thesis is dedicated to understanding and modelling Wet Compression Moulding (WCM) to facilitate large-volume production of CoFRP structural components.
Author | : Thorgeirsson, Adam Thor |
Publisher | : KIT Scientific Publishing |
Total Pages | : 190 |
Release | : 2024-09-03 |
Genre | : |
ISBN | : 3731513714 |
In this work, an extension of the federated averaging algorithm, FedAvg-Gaussian, is applied to train probabilistic neural networks. The performance advantage of probabilistic prediction models is demonstrated and it is shown that federated learning can improve driving range prediction. Using probabilistic predictions, routing and charge planning based on destination attainability can be applied. Furthermore, it is shown that probabilistic predictions lead to reduced travel time.
Author | : Meyer, Nils |
Publisher | : KIT Scientific Publishing |
Total Pages | : 292 |
Release | : 2022-07-12 |
Genre | : Technology & Engineering |
ISBN | : 3731511738 |
Sheet Molding Compounds (SMC) are discontinuous fiber reinforced composites that are widely applied due to their ability to realize composite parts with long fibers at low cost. A novel Direct Bundle Simulation (DBS) method is proposed in this work to enable a direct simulation at component scale utilizing the observation that fiber bundles often remain in a bundled configuration during SMC compression molding.
Author | : Jauch, Jens |
Publisher | : KIT Scientific Publishing |
Total Pages | : 264 |
Release | : 2024-03-01 |
Genre | : |
ISBN | : 3731513323 |
This work describes a method for weighted least squares approximation of an unbounded number of data points using a B-spline function. The method can shift the bounded B-spline function definition range during run-time. The approximation method is used for optimizing velocity trajectories for an electric vehicle with respect to travel time, comfort and energy consumption. The trajectory optimization method is extended to a driver assistance system for automated vehicle longitudinal control.
Author | : Pinay, Julien |
Publisher | : KIT Scientific Publishing |
Total Pages | : 196 |
Release | : 2024-01-16 |
Genre | : |
ISBN | : 3731513285 |
Ihrer Arbeit in der Originalsprache: This work aims at identifying relevant road surface characteristics to mitigate tire-road noise of free-rolling tires using a systematic approach. As using open porous roads is already known as an efficient measure to reduce tire rolling noise, this study will focus on compact road surfaces which have a low acoustic absorption. Measurements on standardized ISO 10844 test tracks and on public roads are used to study the norm's representativity and its completeness.
Author | : Wittemann, Florian |
Publisher | : KIT Scientific Publishing |
Total Pages | : 180 |
Release | : 2022-11-18 |
Genre | : Technology & Engineering |
ISBN | : 3731512173 |
This work presents novel simulation techniques for injection molding of fiber reinforced polymers. These include approaches for anisotropic flow modeling, hydrodynamic forces from fluid on fibers, contact forces between fibers, a novel fiber breakage modeling approach and anisotropic warpage analysis. Due to the coupling of fiber breakage and anisotropic flow modeling, the fiber breakage directly influences the modeled cavity pressure, which is validated with experimental data.