Modeling transverse micro flow in dry fiber placement preforms

2019 ◽  
Vol 54 (13) ◽  
pp. 1691-1703
Author(s):  
Oliver Rimmel ◽  
David May
Keyword(s):  
Flow Behavior ◽  
Liquid Composite Molding ◽  
Textile Materials ◽  
Micro Scale ◽  
Fiber Placement ◽  
Macro Scale ◽  
Out Of Plane ◽  
Numerical Solver ◽  
Analytical Approaches ◽  
Meso Scale

Dry fiber placement has a large potential for manufacturing preforms for primary-load components at minimum scrap rate and fiber crimp. Yet, challenging impregnation behavior due to low permeability of these preforms during liquid composite molding imposes a need for further research to optimize preform structure for higher permeability. For full understanding of flow behavior within these preforms, flow has to be considered on micro scale (in between single fibers), on meso scale (in between single rovings or strands), and on macro scale (on scale of parts to be manufactured). While macro and meso scale can be measured in experiments or derived from filling times in real processes, micro scale is usually not easily assessable and accessible for standard textile materials. Analytical approaches are limited to regular fiber arrangements (square and hexagonal) that are strongly differing from real arrangements. The present work deals with application of a numerical solver to random fiber arrangements to determine micro permeability transverse to the fiber orientation, for later use in meso- and macro-scaled models. As a premise for reliable calculation, guidelines for boundary conditions as well as size and resolution of the representative volume element are elaborated in the course of this work. Calculated out-of-plane micro permeabilities are subsequently compared to real experiments and show good accordance. The influence of binder particles on micro permeability has not yet been conclusively clarified.

scholarly journals Simulation of the forming process for curved composite sandwich panels

2019 ◽  
Vol 13 (6) ◽  
pp. 967-980
Author(s):  
S. Chen ◽  
O. P. L. McGregor ◽  
A. Endruweit ◽  
L. T. Harper ◽  
N. A. Warrior
Keyword(s):  
Sandwich Panels ◽  
High Volume ◽  
Core Structure ◽  
Scale Model ◽  
Axial Deformation ◽  
Forming Process ◽  
The Core ◽  
Macro Scale ◽  
Out Of Plane ◽  
Meso Scale

AbstractFor affordable high-volume manufacture of sandwich panels with complex curvature and varying thickness, fabric skins and a core structure are simultaneously press-formed using a set of matched tools. A finite-element-based process simulation was developed, which takes into account shearing of the reinforcement skins, multi-axial deformation of the core structure, and friction at the interfaces. Meso-scale sandwich models, based on measured properties of the honeycomb cell walls, indicate that panels deform primarily in bending if out-of-plane movement of the core is unconstrained, while local through-thickness crushing of the core is more important in the presence of stronger constraints. As computational costs for meso-scale models are high, a complementary macro-scale model was developed for simulation of larger components. This is based on experimentally determined homogenised properties of the honeycomb core. The macro-scale model was employed to analyse forming of a generic component. Simulations predicted the poor localised conformity of the sandwich to the tool, as observed on a physical component. It was also predicted accurately that fibre shear angles in the skins are below the critical angle for onset of fabric wrinkling.

Liquid Composite Molding: A Widely Used Group of FRPC Processing Techniques, but still a Challenging Topic

2016 ◽  
Vol 879 ◽  
pp. 1715-1720
Author(s):  
Ralf Schledjewski ◽  
Harald Grössing
Keyword(s):  
Process Development ◽  
Flow Behavior ◽  
Process Efficiency ◽  
Liquid Composite Molding ◽  
Advantages And Disadvantages ◽  
Thermoset Resin ◽  
Reinforced Plastic ◽  
Composite Molding ◽  
Out Of Plane ◽  
Processing Techniques

Liquid Composite Molding techniques are widely used technologies in order to manufacture fiber reinforced plastic composites using near-net-shaped preforms consisting of single reinforcements, e.g. woven textiles or multiaxial fabrics. All LCM process variants have in common to impregnate and saturate dry reinforcing structures with a liquid thermoset resin system. The challenge during LCM process development and mold designing is the prevention of potential error sources for safe in-spec FRPC production. Race tracking zones and air inclusions are two major issues which need to be avoided in order to ensure an excellent FRPC quality. The knowledge about preform transmissibility, i.e. permeability, of the dry reinforcing structure to the liquid flow during the saturation phase is of major importance. The knowledge about the filling and flow behavior during FRPC processing is responsible for the process efficiency and process success. In-plane and out-of-plane permeability characterization is of great interest. Especially industry is interested in precise permeability values for numerical mold filling simulations in order to support the process development and the mold design. Industrial work is also carried out for filling strategies and textile development as well as textile improvement. The paper presents different LCM processing techniques and discusses the advantages and disadvantages as well as the linked challenges during FRPC processing. Furthermore, the in-plane permeability characterization of reinforcing structures and moreover influencing factors on the filling behavior are presented. Finally the significance of accurate and reliable permeability values according to numerical filling simulations and their validity are discussed.

scholarly journals Micro-Scale Permeability Characterization of Carbon Fiber Composites Using Micrograph Volume Elements

2021 ◽  
Vol 8 ◽  
Author(s):  
Julian Seuffert ◽  
Lars Bittrich ◽  
Leonardo Cardoso de Oliveira ◽  
Axel Spickenheuer ◽  
Luise Kärger
Keyword(s):  
High Performance ◽  
Fluid Dynamic ◽  
Stochastic Approach ◽  
Carbon Fiber Composites ◽  
Liquid Composite Molding ◽  
Fiber Distribution ◽  
Dynamic Simulations ◽  
Micro Scale ◽  
Fiber Placement ◽  
Reinforced Plastics

To manufacture a high-performance structure made of continuous fiber reinforced plastics, Liquid Composite Molding processes are used, where a liquid resin infiltrates the dry fibers. For a good infiltration quality without dry spots, it is important to predict the resin flow correctly. Knowledge of the local permeability is an essential precondition for mold-filling simulations. In our approach, the intra-bundle permeability parallel and transverse to the fibers is characterized via periodic fluid dynamic simulations of micro-scale volume elements (VE). We evaluate and compare two approaches: First, an approach to generate VEs based on a statistical distribution of the fibers and fiber diameters. Second, an approach based on micrograph images of samples manufactured with Tailored Fiber Placement (TFP) using the measured fiber distribution. The micrograph images show a higher heterogeneity of the distribution than the statistically generated VEs, which is characterized by large resin areas. This heterogeneity leads to a significantly different permeability compared to the stochastic approach. In conclusion, a pure stochastic approach needs to contain the large heterogeneity of the fiber distribution to predict correct permeability values.

A Three-Level Approach to Texture Mapping and Synthesis on 3D Surfaces

2020 ◽  
Vol 3 (1) ◽  
pp. 1-19
Author(s):  
Kersten Schuster ◽  
Philip Trettner ◽  
Patric Schmitz ◽  
Leif Kobbelt
Keyword(s):  
User Interaction ◽  
Texture Mapping ◽  
Arbitrary Size ◽  
Micro Scale ◽  
Macro Scale ◽  
Texture Sample ◽  
Visual Artifacts ◽  
Meso Scale ◽  
3D Surfaces

We present a method for example-based texturing of triangular 3D meshes. Our algorithm maps a small 2D texture sample onto objects of arbitrary size in a seamless fashion, with no visible repetitions and low overall distortion. It requires minimal user interaction and can be applied to complex, multi-layered input materials that are not required to be tileable. Our framework integrates a patch-based approach with per-pixel compositing. To minimize visual artifacts, we run a three-level optimization that starts with a rigid alignment of texture patches (macro scale), then continues with non-rigid adjustments (meso scale) and finally performs pixel-level texture blending (micro scale). We demonstrate that the relevance of the three levels depends on the texture content and type (stochastic, structured, or anisotropic textures).

scholarly journals Simulation of dry powder inhalers: Combining micro-scale, meso-scale and macro-scale modeling

AIChE Journal ◽  
2016 ◽  
Vol 63 (2) ◽  
pp. 501-516 ◽  
Author(s):  
Berend van Wachem ◽  
Kyrre Thalberg ◽  
Johan Remmelgas ◽  
Ingela Niklasson-Björn
Keyword(s):  
Dry Powder Inhalers ◽  
Dry Powder ◽  
Micro Scale ◽  
Scale Modeling ◽  
Macro Scale ◽  
Meso Scale

scholarly journals TBRs, a methodology for the multi-scalar cartographic analysis of the distribution of plant formations

2020 ◽  
Author(s):  
Rafael Cámara Artigas ◽  
Fernando Díaz del Olmo ◽  
Jose Ramon Martinez Batlle
Keyword(s):  
Water Balance ◽  
Distribution Map ◽  
Biomass Distribution ◽  
Micro Scale ◽  
Multi Scale ◽  
Macro Scale ◽  
Bioclimatic Variables ◽  
Different Levels ◽  
Meso Scale ◽  
Scale Classification

An analytical and cartographic method of biomass distribution and plant formations at a multi-scalar level is developed based on bioclimatic variables extracted from the Thornthwaite Water Balance (WB) and the Bioclimatic Balances (BB) of Montero de Burgos & González Rebollar. As a result, a distribution map involving Types of Bioclimatic Regimens (TBR) is obtained leading to the identification of a multi-scale classification at different levels: zonal (macro-scale) with 5 types, regional (meso-scale) with 27 types, and local (micro-scale) with 162 plant formations subtypes, conditioned by lithology-soils, the relief exposure to wind or sunstroke respectively and obtained through the combination of TBR and ombroclimates.

scholarly journals A Multi-Scale Modeling Approach for Simulating Crack Sensing in Polymer Fibrous Composites Using Electrically Conductive Carbon Nanotube Networks. Part II: Meso- and Macro-Scale Analyses

Aerospace ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 106 ◽  
Author(s):  
Konstantinos Tserpes ◽  
Christos Kora
Keyword(s):  
Carbon Nanotube ◽  
Fibrous Composites ◽  
Electrically Conductive ◽  
Micro Scale ◽  
Multi Scale ◽  
Modeling Approach ◽  
Scale Modeling ◽  
Macro Scale ◽  
Multi Scale Modeling ◽  
Meso Scale

This is the second of a two-paper series describing a multi-scale modeling approach developed to simulate crack sensing in polymer fibrous composites by exploiting interruption of electrically conductive carbon nanotube (CNT) networks. The approach is based on the finite element (FE) method. Numerical models at three different scales, namely the micro-scale, the meso-scale and the macro-scale, have been developed using the ANSYS APDL environment. In the present paper, the meso- and macro-scale analyses are described. In the meso-scale, a two-dimensional model of the CNT/polymer matrix reinforced by carbon fibers is used to develop a crack sensing methodology from a parametric study which relates the crack position and length with the reduction of current flow. In the meso-model, the effective electrical conductivity of the CNT/polymer computed from the micro-scale is used as input. In the macro-scale, the final implementation of the crack sensing methodology is performed on a CNT/polymer/carbon fiber composite volume using as input the electrical response of the cracked CNT/polymer derived at the micro-scale and the crack sensing methodology. Analyses have been performed for cracks of two different lengths. In both cases, the numerical model predicts with good accuracy both the length and position of the crack. These results highlight the prospect of conductive CNT networks to be used as a localized structural health monitoring technique.

scholarly journals A Multi-Scale Modeling Approach for Simulating Crack Sensing in Polymer Fibrous Composites Using Electrically Conductive Carbon Nanotube Networks. Part II: Meso- and Macro-Scale Analyses

2018 ◽  
Author(s):  
Konstantinos Tserpes ◽  
Christos Kora
Keyword(s):  
Carbon Nanotube ◽  
Fibrous Composites ◽  
Electrically Conductive ◽  
Micro Scale ◽  
Multi Scale ◽  
Modeling Approach ◽  
Scale Modeling ◽  
Macro Scale ◽  
Multi Scale Modeling ◽  
Meso Scale

This is the second of a two-paper series describing a multi-scale modeling approach developed to simulate crack sensing in polymer fibrous composites by exploiting interruption of electrically conductive carbon nanotube (CNT) networks. The approach is based on the finite element (FE) method. FE models at three different scales, namely the micro-scale, the meso-scale and the macro-scale, have been developed using the ANSYS PDL environment. In the present paper, the meso- and macro-scale analyses are described. In the meso-scale, a two-dimensional model of the CNT/polymer matrix reinforced by carbon fibers is used to develop a crack sensing methodology from a parametric study which relates the crack position and length with the reduction of current flow. In the meso-model, the effective electrical conductivity of the CNT/polymer computed from the micro-scale is used as input. In the macro-scale, the final implementation of the crack sensing methodology is performed on a CNT/polymer/carbon fiber composite volume using as input the electrical response of the cracked CNT/polymer derived at the micro-scale and the crack sensing methodology. Analyses have been performed for cracks of two different lengths. In both cases, the numerical model predicts with good accuracy both the length and position of the crack. These results highlight the prospect of conductive CNT networks to be used as a localized structural health monitoring technique.

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