DESIGN OF A COMPOSITE PANEL WITH CONTINUOUS TOW STEERING AROUND AN ELLIPTICAL CUT-OUT

2021 ◽  
Author(s):  
GIOVANNI ZUCCO ◽  
MOHAMMAD ROUHI ◽  
OLIVERI VINCENZO ◽  
ENZO COSENTINO ◽  
RONAN O’HIGGINS ◽  
...  
Keyword(s):  
Composite Panel ◽  
Stress And Strain ◽  
Stress Strain ◽  
Strain Concentration ◽  
Compression Loading ◽  
Fiber Placement ◽  
Aerospace Applications ◽  
Concentration Problem ◽  
Automated Fiber Placement ◽  
Straight Fiber

Cut-outs are inevitable in many structural components such as in aircrafts to accommodate windows or openings for access purposes or fasteners. Engineers usually view cut-outs, especially in primary structures, with disfavour as they result in stress/strain concentration and consequently reduced load carrying capability. Local reinforcements usually increase cost and weight to the overall design which is not favourable in aerospace applications. In case of composite panels, emerging advanced manufacturing methods such as 3D printing of automated fiber placement made it possible to continuously steer fibers/tows around a cut-out to potentially alleviate stress/strain concentration problem. Another advantage of tow steering in this case is maintaining the continuity of fiber/tow paths without any fiber cut which precludes ply-level, 3D stress/strain concentration which could otherwise lead to delaminationinduced damage. In this study, potential capability of tow steering around an elliptical cut-out (manhole) in reducing stress/strain concentration in a composite wingbox is investigated Buckling response under compression loading together with stress and strain concentrations under both tensile and compression loads are examined. Under tensile loading, the maximum stress and strain concentration factors around the cut-out in the straight fiber design are shown to be approximately 29% and 32% larger than its counterpart with steered tows around the cut-out. For the compression loading condition, the direct strain of the panel with straight fiber orientations was found to be three times that of steered fiber trajectories in the vicinity of the cut-out.

scholarly journals Simulation of laser heating distribution for a thermoplastic composite: effects of AFP head parameters

2020 ◽  
Vol 110 (7-8) ◽  
pp. 2105-2117
Author(s):  
Omar Baho ◽  
Gilles Ausias ◽  
Yves Grohens ◽  
Julien Férec
Keyword(s):  
Laser Beam ◽  
Laser Heating ◽  
Thermal Model ◽  
Laser Energy ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Efficient Production ◽  
Fiber Placement ◽  
Aerospace Applications ◽  
Automated Fiber Placement

Abstract Laser-assisted automated fiber placement (AFP) is highly suitable for an efficient production of thermoplastic-matrix composite parts, especially for aeronautic/aerospace applications. Heat input by laser heating provides many advantages such as better temperature controls and uniform heating projections. However, this laser beam distribution can be affected by the AFP head system, mainly at the roller level. In this paper, a new optico-thermal model is established to evaluate the laser energy quantity absorbed by a poly(ether ether ketone) reinforced with carbon fibers (APC-2). During the simulation process, the illuminated radiative material properties are characterized and evaluated in terms of the roller deformation, the tilt of the robot head, and the reflection phenomenon between the substrate and the incoming tape. After computing the radiative source term using a ray-tracing method, these data are used to predict the temperature distribution on both heated surfaces of the composite during the process. The results show that both the roller deformation and the tilt of head make it possible to focus the laser beam on a small area, which considerably affects the quality of the finished part. These findings demonstrate that this optico-thermal model can be used to predict numerically the insufficient heating area and thermoplastic composites heating law.

Microvascular Composites for Thermal Management

2014 ◽  
Author(s):  
Konstantine A. Fetfatsidis ◽  
Amanda Dropkin ◽  
Paul Dahlstrand ◽  
Christopher Hansen ◽  
Richard Poillucci ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Thermal Management ◽  
Flow Characteristics ◽  
Carbon Composite ◽  
Mechanical Effect ◽  
Unmanned Aircraft ◽  
Composite Panel ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Network Manufacture

Manned and unmanned aircraft are commonly manufactured from lightweight composite materials, replacing heavier metallic aircraft materials. Here, we describe a collaborative industrial-academic effort to develop novel microvascular composites that offer thermal and structural multifunctionality via embedded micro-capillary array-based heat exchangers for thermal management embedded within aerospace-grade carbon prepreg material. The current research establishes a route to create prepreg materials suitable for heat exchanger network manufacture by automated fiber placement processes. Potential network geometries are investigated with analytical fluid models to predict flow characteristics and heat distribution for pre-defined heat exchanger configurations within a carbon composite panel. Based on these predictions, two geometries are fabricated for thermal management experiments. The mechanical effect of the embedded microvascular networks on the panel structural properties is also investigated analytically.

scholarly journals Overlap-Stiffened Panels for Optimized Buckling Performance Under Minimum Steering Radius Constraints

2020 ◽  
Author(s):  
Raphael Ummels ◽  
Saullo G. P. Castro
Keyword(s):  
Design Method ◽  
Variable Stiffness ◽  
Radius Of Curvature ◽  
Stiffened Panels ◽  
Fiber Placement ◽  
Design Variables ◽  
Automated Fiber Placement ◽  
Circular Fiber ◽  
Straight Fiber ◽  
Radius Constraint

Recent research on variable stiffness laminates have shown both numerically and experimentally that further improvement on the buckling behaviour is possible by incorporating overlaps that result in variable thickness profiles, with the thickness non-linearly coupled with the local steering angle. We present the concept of overlap-stiffened panels, developing a design method that allows for incorporating higher-stiffness regions into individual plies of a variable-angle tow (VAT) laminate, taking advantage of the non-linear coupling between the tow steering angles and the local thickness. The proposed method naturally copes with minimum steering radius constraints of different manufacturing processes, and the present study considers two tow steering processes: automated fiber placement (AFP) and continuous tow shearing (CTS). The minimum radius constraint is satisfied by connecting two transition regions of thickness specified on each ply by means of circular fiber tow arcs, of which the radius of curvature always exceed the minimum manufacturing constraint. Each individual ply exploring the overlap-stiffened design is described using 5 design variables. Laminates made up of these overlap-stiffened plies are optimized for a maximum volume-normalized buckling performance under bi-axial compression, measured through FEM, by a genetic algorithm and benchmarked against a straight fiber panel optimized for the same load case. The conclusion can be drawn that both AFP and CTS overlap-stiffened VAT panels can at least achieve the double of the volume-normalized buckling performance of an optimized straight fiber panel, demonstrating the potential of the proposed design method.

Applicability of Neuber’s Rule to the Analysis of Stress and Strain Concentration Under Creep Conditions

1998 ◽  
Vol 120 (3) ◽  
pp. 224-229 ◽  
Author(s):  
G. Ha¨rkega˚rd ◽  
S. So̸rbo̸
Keyword(s):  
Stress Relaxation ◽  
Elastic Response ◽  
Strain History ◽  
Stress And Strain ◽  
Stress Strain ◽  
Strain Concentration ◽  
Long Time ◽  
Concentration Factors ◽  
Neuber's Rule ◽  
Good Agreement

A differential form of Neuber’s rule, originally proposed by M. Chaudonneret, has been formulated for a generic viscoplastic notch problem, making extensive use of suitably normalised stress, strain and time. It has been shown that the stress-strain history at the root of a notch in a viscoplastic body can be determined directly from the elastic response, provided far-field viscoplastic strains can be neglected. Neuber’s rule has also been applied to the more general cases of stress and strain concentration at notches under (i) nominal creep conditions (constant nominal stress) and (ii) stress relaxation (constant nominal strain). Predictions are in good agreement with results from finite element analyses. Stress and strain concentration factors have been observed to approach stationary values after long-time loading. The stationary stress concentration factor under stress relaxation falls below that under nominal creep conditions.

Automated Fiber Placement of Composite Wind Tunnel Blades: Process Planning and Manufacturing

2019 ◽  
Author(s):  
Ramy Harik ◽  
Joshua Halbritter ◽  
Dawn Jegley ◽  
Ray Grenoble ◽  
Brian Mason
Keyword(s):  
Wind Tunnel ◽  
Process Planning ◽  
Fiber Placement ◽  
Automated Fiber Placement

scholarly journals Review: Filament Winding and Automated Fiber Placement with In Situ Consolidation for Fiber Reinforced Thermoplastic Polymer Composites

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1951
Author(s):  
Yi Di Boon ◽  
Sunil Chandrakant Joshi ◽  
Somen Kumar Bhudolia
Keyword(s):  
Processing Parameters ◽  
Filament Winding ◽  
Reference Points ◽  
Thermoplastic Composites ◽  
Manufacturing Processes ◽  
Fiber Reinforced ◽  
Consolidation Process ◽  
Fiber Placement ◽  
Automated Fiber Placement

Fiber reinforced thermoplastic composites are gaining popularity in many industries due to their short consolidation cycles, among other advantages over thermoset-based composites. Computer aided manufacturing processes, such as filament winding and automated fiber placement, have been used conventionally for thermoset-based composites. The automated processes can be adapted to include in situ consolidation for the fabrication of thermoplastic-based composites. In this paper, a detailed literature review on the factors affecting the in situ consolidation process is presented. The models used to study the various aspects of the in situ consolidation process are discussed. The processing parameters that gave good consolidation results in past studies are compiled and highlighted. The parameters can be used as reference points for future studies to further improve the automated manufacturing processes.

Effect of gap on strengths of automated fiber placement manufactured laminates

2021 ◽  
Vol 263 ◽  
pp. 113677
Author(s):  
Hiroshi Suemasu ◽  
Yuichiro Aoki ◽  
Sunao Sugimoto ◽  
Toshiya Nakamura
Keyword(s):  
Fiber Placement ◽  
Automated Fiber Placement

scholarly journals Experimental Investigation on the Influence of Fiber Path Curvature on the Mechanical Properties of Composites

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2602
Author(s):  
Huaqiao Wang ◽  
Jihong Chen ◽  
Zhichao Fan ◽  
Jun Xiao ◽  
Xianfeng Wang
Keyword(s):  
Tensile Strength ◽  
Path Planning ◽  
Composite Laminates ◽  
Bending Strength ◽  
High Strength ◽  
Bending Test ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Fiber Path ◽  
Path Curvature

Automated fiber placement (AFP) has been widely used as an advanced manufacturing technology for large and complex composite parts and the trajectory planning of the laying path is the primary task of AFP technology. Proposed in this paper is an experimental study on the effect of several different path planning placements on the mechanical behavior of laminated materials. The prepreg selected for the experiment was high-strength toughened epoxy resin T300 carbon fiber prepreg UH3033-150. The composite laminates with variable angles were prepared by an eight-tow seven-axis linkage laying machine. After the curing process, the composite laminates were conducted by tensile and bending test separately. The test results show that there exists an optimal planning path among these for which the tensile strength of the laminated specimens decreases slightly by only 3.889%, while the bending strength increases greatly by 16.68%. It can be found that for the specific planning path placement, the bending strength of the composite laminates is significantly improved regardless of the little difference in tensile strength, which shows the importance of path planning and this may be used as a guideline for future AFP process.

Mechanical characterization of a woven multi-layered hyperelastic composite laminate under uniaxial loading

2021 ◽  
pp. 002199832110115
Author(s):  
Shaikbepari Mohmmed Khajamoinuddin ◽  
Aritra Chatterjee ◽  
MR Bhat ◽  
Dineshkumar Harursampath ◽  
Namrata Gundiah
Keyword(s):  
Composite Materials ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Mechanical Tests ◽  
Stress Strain ◽  
Aerospace Applications ◽  
Envelope Material ◽  
The Individual ◽  
High Dielectric

We characterize the material properties of a woven, multi-layered, hyperelastic composite that is useful as an envelope material for high-altitude stratospheric airships and in the design of other large structures. The composite was fabricated by sandwiching a polyaramid Nomex® core, with good tensile strength, between polyimide Kapton® films with high dielectric constant, and cured with epoxy using a vacuum bagging technique. Uniaxial mechanical tests were used to stretch the individual materials and the composite to failure in the longitudinal and transverse directions respectively. The experimental data for Kapton® were fit to a five-parameter Yeoh form of nonlinear, hyperelastic and isotropic constitutive model. Image analysis of the Nomex® sheets, obtained using scanning electron microscopy, demonstrate two families of symmetrically oriented fibers at 69.3°± 7.4° and 129°± 5.3°. Stress-strain results for Nomex® were fit to a nonlinear and orthotropic Holzapfel-Gasser-Ogden (HGO) hyperelastic model with two fiber families. We used a linear decomposition of the strain energy function for the composite, based on the individual strain energy functions for Kapton® and Nomex®, obtained using experimental results. A rule of mixtures approach, using volume fractions of individual constituents present in the composite during specimen fabrication, was used to formulate the strain energy function for the composite. Model results for the composite were in good agreement with experimental stress-strain data. Constitutive properties for woven composite materials, combining nonlinear elastic properties within a composite materials framework, are required in the design of laminated pretensioned structures for civil engineering and in aerospace applications.

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