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Jegley, Dawn

Publications and source records attributed to Jegley, Dawn.

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

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

The ability to accurately manufacture large complex shapes in a consistent and repeatable manner has led to Automated Fiber Placement (AFP) being the predominant mode of manufacturing for large composite aerospace structures today. Currently, AFP is being considered for medium- and small-scale parts. Composite wind tunnel blades have traditionally been fabricated by hand layup for pre-impregnated or dry fabrics with resin infusion. Though well proven, the traditional fabrication method is laborious and tedious, and hence expensive. The project described in this paper used the Integral Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to build a manufacturing demonstration unit (MDU) with a shape representative of a wind tunnel blade. This MDU is used to discuss tooling, process planning, and fabrication. Additionally, details of the generic manufacturing workflow are presented.

Harik, Ramy↗
NASA NTRS2019

Assessment of Automated Fiber Placement for the Fabrication of Composite Wind Tunnel Blades

Composite wind tunnel blades are frequently fabricated by hand layup of prepreg fabrics. Though well proven, this fabrication method is laborious and expensive. The study described in this paper used the Integrated Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to explore whether automated fiber placement (AFP) could reduce manufacturing time and cost for production of wind tunnel blades. Two blades, taken from two NASA wind tunnels, were investigated as representative geometries. Computer-aided design models of the blade surfaces were created, and AFP process planning and programming were employed to study the manufacturability of the shapes. A placement/cure tool was manufactured for the chosen blade surface from thermoplastic material using an additive manufacturing process. The present study revealed that the AFP head geometry, primarily the heater configuration of the ISAAC system, is the primary constraint that limits the ability to manufacture the selected wind tunnel fan blades using AFP.

Grenoble, Ray↗
NASA NTRS2019

Impact Damage Tolerance of Composite Laminates with Through-The-Thickness Stitches

The ability of through-the-thickness stitches to contain damage during a low-velocity impact event and increase the residual strength of stitched panels was investigated in this research. The impact response, spread of interlaminar delaminations, dent depth, surface damage, and static residual strength after impact were studied for carbon-epoxy specimens fabricated from HTS40 TohoTenax standard modulus fibers, stitched together with Vectran 1200 denier thread and infused with API 1078 resin after through-the-thickness stitching. Three different stitch patterns were used to explore the ability to arrest impact damage during and after impact. Simply supported boundary conditions were maintained during the impact testing. Non-destructive evaluations were performed using ultrasonic C-scans and X-ray computed tomography (CT) imaging to determine the shape, size, and location of delaminations. Results indicate that while the dynamic response during the impact event was almost the same for the unstitched specimens and all stitch patterns considered, the extent of delamination and the compression strength after impact varied greatly. For both the 60 J and 80 J impact energies, the delamination area was significantly less for the stitched specimens than for the unstitched specimens, but the range of delamination areas among the stitch patterns was much larger for the lower impact energy than for the greater impact energy. Similarly, while the presence of stitching influenced the compression after impact strength, the strength values for all stitch patterns were very similar. These results are a step toward quantifying the influence of through-the-thickness stitching.

Ranatunga, Vipul↗
NASA NTRS2018

Fabrication of a Composite Tow-Steered Structure for Air-Launch Vehicle Applications

Generation Orbit (GO) is developing the GO Launcher-1 (GO-1), a single stage liquid rocket that is launched from a Gulfstream III carrier aircraft platform. The vehicle is designed as the next generation platform for hypersonic flight testing and suborbital microgravity research. To reduce mass and increase payload, GO partnered with NASA Langley Research Center to design, analyze, optimize, and fabricate a tow-steered manufacturing development unit of a cylindrical section of a liquid oxygen tank. The fabrication process of using the ISAAC (Integrated Structural Assembly of Advanced Composites) system is described. The structural design challenges and the concept design solutions are also presented to provide the context for the fabrication process. The in-situ nondestructive evaluation supporting the effort is also described.

Grenoble, Ray↗
NASA NTRS2016

Testing of a Stitched Composite Large-Scale Multi-Bay Pressure Box

NASA has created the Environmentally Responsible Aviation (ERA) Project to develop technologies to reduce aviation's impact on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe to enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company have worked together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composite structures. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together. The PRSEUS concept is designed to maintain residual load carrying capabilities under a variety of damage scenarios. A series of building block tests were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. The final step in the building block series is an 80%-scale pressure box representing a portion of the center section of a Hybrid Wing Body (HWB) transport aircraft. The testing of this article under maneuver load and internal pressure load conditions is the subject of this paper. The experimental evaluation of this article, along with the other building block tests and the accompanying analyses, has demonstrated the viability of a PRSEUS center body for the HWB vehicle. Additionally, much of the development effort is also applicable to traditional tube-and-wing aircraft, advanced aircraft configurations, and other structures where weight and through-the-thickness strength are design considerations.

Jegley, Dawn↗
NASA NTRS2015

Development of Stitched Composite Structure for Advanced Aircraft

NASA has created the Environmentally Responsible Aviation Project to develop technologies which will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company are working together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composites. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. With the PRSEUS concept, through-the-thickness stitches are applied through dry fabric prior to resin infusion, and replace fasteners throughout each integral panel. Through-the-thickness reinforcement at discontinuities, such as along flange edges, has been shown to suppress delamination and turn cracks, which expands the design space and leads to lighter designs. The pultruded rod provides stiffening away from the more vulnerable skin surface and improves bending stiffness. A series of building blocks were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. These building blocks addressed tension, compression, and pressure loading conditions. The emphasis of the development work has been to assess the loading capability, damage arrestment features, repairability, post-buckling behavior, and response of PRSEUS flat panels to out-of plane pressure loading. The results of this building-block program from coupons through an 80%-scale pressure box have demonstrated the viability of a PRSEUS center body for the Hybrid Wing Body (HWB) transport aircraft. This development program shows that the PRSEUS benefits are also applicable to traditional tube-andwing aircraft, those of advanced configurations, and other structures where weight and through-the-thickness strength are design considerations. An overview of the development of PRSEUS technology for commercial transport aircraft is the subject of this paper.

Jegley, Dawn↗
NASA NTRS2015

Preparation for Testing a Multi-Bay Box Subjected to Combined Loads

The COmbined Loads Test System (COLTS) facility at NASA Langley Research Center provides a test capability to help develop validated structures technologies. The test machine was design to accommodate a range of fuselage structures and wing sections and subject them to both quasistatic and cyclic loading conditions. The COLTS facility is capable of testing fuselage barrels up to 4.6 m in diameter and 13.7 m long with combined mechanical, internal pressure, and thermal loads. The COLTS facility is currently being prepared to conduct a combined mechanical and pressure loading for a multi-bay pressure box to experimentally verify the structural performance of a composite structure which is 9.1 meters long and representative of a section of a hybrid wing body fuselage section in support of the Environmentally Responsible Aviation Project at NASA. This paper describes development of the multi-bay pressure box test using the COLTS facility. The multi-bay test article will be subjected to mechanical loads and internal pressure loads up to design ultimate load. Mechanical and pressure loads will be applied independently in some tests and simultaneously in others.

Rouse, Marshall↗
NASA NTRS2015

Status of ERA Airframe Technology Demonstrators

NASA has created the Environmentally Responsible Aviation (ERA) Project to explore and document the feasibility, benefits and technical risk of advanced vehicle configurations and enabling technologies that will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations that have higher lift-to-drag ratios, reduced drag, and lower community noise. The Airframe Technology subproject contains two elements. Under the Damage Arresting Composite Demonstration an advanced material system is being explored which will lead to lighter airframes that are more structural efficient than the composites used in aircraft today. Under the Adaptive Compliant Trailing Edge Flight Experiment a new concept of a flexible wing trailing edge is being evaluated which will reduce weight and improve aerodynamic performance. This presentation will describe the development these two airframe technologies.

Davis, Pamela↗
NASA NTRS2014

PRSEUS Structural Concept Development

A lighter, more robust airframe is one of the key technological advancements necessary for the successful launch of any large next-generation transport aircraft. Such a premise dictates that considerable improvements beyond current state-of-the-art aluminum structures is needed, and that improvements of this magnitude will require an extensive use of composite materials that are not only lightweight, but also economical to produce. To address this challenge, researchers at NASA and The Boeing Company are developing a novel structural concept called the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) under the Environmentally Responsible Aviation (ERA) Project. It is an integrally stiffened panel concept that is stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. In addition to improved structural performance, an important facet of this unique arrangement of stitched carbon fibers is its innovative manufacturing method that has the potential to lower fabrication costs by eliminating fasteners and autoclave cures. The rationale and development status for this new approach forms the basis of the work described in this paper. The test specimens described herein were fabricated, or are currently being fabricated, by The Boeing Company, while the structural analyses and testing tasks are being performed by NASA and Boeing personnel.

Velicki, Alex↗
NASA NTRS2013

Nonlinear Analysis and Post-Test Correlation for a Curved PRSEUS Panel

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, developed by The Boeing Company, has been extensively studied as part of the National Aeronautics and Space Administration's (NASA s) Environmentally Responsible Aviation (ERA) Program. The PRSEUS concept provides a light-weight alternative to aluminum or traditional composite design concepts and is applicable to traditional-shaped fuselage barrels and wings, as well as advanced configurations such as a hybrid wing body or truss braced wings. Therefore, NASA, the Federal Aviation Administration (FAA) and The Boeing Company partnered in an effort to assess the performance and damage arrestments capabilities of a PRSEUS concept panel using a full-scale curved panel in the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. Testing was conducted in the FASTER facility by subjecting the panel to axial tension loads applied to the ends of the panel, internal pressure, and combined axial tension and internal pressure loadings. Additionally, reactive hoop loads were applied to the skin and frames of the panel along its edges. The panel successfully supported the required design loads in the pristine condition and with a severed stiffener. The panel also demonstrated that the PRSEUS concept could arrest the progression of damage including crack arrestment and crack turning. This paper presents the nonlinear post-test analysis and correlation with test results for the curved PRSEUS panel. It is shown that nonlinear analysis can accurately calculate the behavior of a PRSEUS panel under tension, pressure and combined loading conditions.

Gould, Kevin↗
NASA NTRS2012

Full-Scale Test and Analysis Results of a PRSEUS Fuselage Panel to Assess Damage Containment Features

Integrally stitched composite technology is an area that shows promise in enhancing the structural integrity of aircraft and aerospace structures. The most recent generation of this technology is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. The goal of the PRSEUS concept relevant to this test is to provide damage containment capability for composite structures while reducing overall structural weight. The National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), and The Boeing Company have partnered in an effort to assess the damage containment features of a full-scale curved PRSEUS panel using the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. A single PRSEUS test panel was subjected to axial tension, internal pressure, and combined axial tension and internal pressure loads. The test results showed excellent performance of the PRSEUS concept. No growth of Barely Visible Impact Damage (BVID) was observed after ultimate loads were applied. With a two-bay notch severing the central stringer, damage was contained within the two-bay region well above the required limit load conditions. Catastrophic failure was well above the ultimate load level. Information describing the test panel and procedure has been previously presented, so this paper focuses on the experimental procedure, test results, nondestructive inspection results, and preliminary test and analysis correlation.

Bergan, Andrew↗
NASA NTRS2011

PRSEUS Development for the Hybrid Wing Body Aircraft

NASA has created the Environmentally Responsible Aviation (ERA) Project to explore and document the feasibility, benefits and technical risk of advanced vehicle configurations and enabling technologies that will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations that have higher lift to drag ratios, reduced drag, and lower community noise. The primary structural concept being developed for the Hybrid Wing Body aircraft design under the ERA project in the Airframe Technology element is the PRSEUS concept. This paper describes how researchers at NASA and Boeing are working together to develop fundamental PRSEUS technologies that could someday be implemented on a transport size HWB airplane design.

Velicki, Alex↗
NASA NTRS2002

Design and Manufacture of Elastically Tailored Tow Placed Plates

Elastic stiffness tailoring of laminated composite panels by allowing the fibers to curve within the plane of the laminate is a relatively novel design concept that has been demonstrated to be both beneficial and practical. In particular, for structures with highly non-uniform stress states, such as the case of a flat panel with a central hole subjected to in-plane loading, the concept is likely to provide substantial improvements in load carrying capability. The objective of the present study is to determine the effectiveness of stiffness tailoring through the use of curvilinear fibers to reduce stress concentrations around the hole and improve the load carrying capability of panels with holes. In this study software was created that translates standard finite element models with traditional laminate definitions into ones that possess stacking sequences with curvilinear fiber paths that are directly manufacturable using an advanced tow placement machine. Preliminary designs for the manufacturing and testing phase were determined through rudimentary design studies for flat plates without holes under axial compression. These candidate designs were then analyzed using finite element models that accurately reflect the test conditions and geometries in order to select final designs for testing. A total of six large panels, measuring three feet by six feet, each of which are used to produce four specimens with or without holes, were fabricated and delivered to NASA for machining and testing.

Tatting, Brain F.↗
NASA NTRS1992

Effect of low-speed impact damage and damage location on behavior of composite panels

An investigation of the effects of low-speed impact damage on the compression and tension strength of thin (less than .05 inches thick) and moderately thick (between .12 and .17 inches thick) composite specimens was conducted. Impact speeds ranged from 50 to 550 ft/sec (impact energies from .25 to 30.7 ft-lb) and impact locations were near or away from a lateral unloaded edge. In this study, thin tension-loaded or compression-loaded specimens with only 90 deg and +/- 40 deg plies which were impacted away from the unloaded edge suffered less reduction in maximum load-carrying capability due to impact damage than the same specimens impacted near the unloaded edge. Unlike the thin laminates, failure loads of thicker compression-loaded specimens with a similar stacking sequence were independent of impact location. Failure loads of thin tension-loaded specimens with 0 deg plies were independent of impact location while failure loads of thicker compression-loaded specimens with 0 deg plies were dependent upon impact location. A finite-element analysis of strain distributions across the panel width indicated that high axial strains occur near the unloaded edges of postbuckled panels, indicating that impacts near the unloaded edge would significantly effect the behavior of postbuckled panels.

Jegley, Dawn↗