ARMD Workshop on Materials and Methods for Rapid Manufacturing for Commercial and Urban Aviation

This report documents the goals, organization and outcomes of the NASA Aeronautics Research Mission Directorates (ARMD) Materials and Methods for Rapid Manufacturing for Commercial and Urban Aviation Workshop. The workshop began with a series of plenary presentations by leaders in the field of structures and materials, followed by concurrent symposia focused on forecasting the future of various technologies related to rapid manufacturing of metallic materials and polymeric matrix composites, referred to herein as composites. Shortly after the workshop, questionnaires were sent to key workshop participants from the aerospace industry with requests to rank the importance of a series of potential investment areas identified during the workshop. Outcomes from the workshop and subsequent questionnaires are being used as guidance for NASA investments in this important technology area

Stochastic heat transfer simulation of the cure of advanced composites

A stochastic cure simulation approach is developed to investigate the variability of the cure process during resin infusion related to thermal effects. Boundary condition uncertainty is quantified experimentally and appropriate stochastic processes are developed to represent the variability in tool/air temperature and surface heat transfer coefficient. The heat transfer coefficient presents a variation across different experiments of 12.3%, whilst the tool/air temperatures present a standard deviation over 1℃. The boundary condition variability is combined with an existing model of cure kinetics uncertainty and the full stochastic problem is addressed by coupling a cure model with Monte Carlo and the Probabilistic Collocation Method and applied to the case of thin carbon epoxy laminates. The overall variability in cure time reaches a coefficient of variation of about 22%, which is dominated by uncertainty in surface heat transfer and tool temperature; with ambient temperature and kinetics contributing variability in the order of 1%

Development of a co-cured composite torque shaft for rudder of high speed aircraft

The Carbon Fibre reinforced Composites are widely used in developing various composite parts of civil and13; military aircraft due to its high specific strength and specific stiffness. Rudder being a primary control surface in an aircraft, it is subjected to various loads and needs high degree of structural integrity. Usually rudders are made of metal with many fasteners. In NAL we have designed and developed a composite rudder. Specialty of this13; rudder is that it has a torque shaft made up of carbon composite and has only few rivets. Conventionally torque13; shaft s are made up of special metals like titanium. The objective of this paper is to highlight the development of13; various tooling techniques used to fabricate the composite torque shaft . All major parts of the torque shaft are13; made by Co-curing technique and the metal attachments are embedded to the composite parts by self locking13; mechanism design. To qualify the torque shaft fatigue tests are done and ageing studies performed to prove13; structural integrity of the torque shaft under extreme environmental conditions. This paper portrays the13; development efforts, tolling and fabrication approaches for successful realization of the CFRP Torque Shaft

Multi-objective optimisation of the cure of thick components

This paper addresses the multi-objective optimisation of the cure stage of composites manufacture. The optimisation aims to minimise the cure process duration and maximum temperature overshoot within the curing part by selecting an appropriate thermal profile. The methodology developed combines a finite element solution of the heat transfer problem with a Genetic Algorithm. The optimisation algorithm approximates successfully and consistently the Pareto optimal front of the multi-objective problem in a variety of characteristic geometries of varying thickness. The results highlight the efficiency opportunities available in comparison with standard industrial cure profiles. In the case of ultra-thick components improvements of up to 70% in terms of overshoot and 14 h in terms of process time, compared to conventional cure profiles for ultra-thick components, can be achieved. In the case of thick components reduction up to 50% can be achieved in both temperature overshoot and process duration

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

Deployment simulation of very large inflatable tensegrity reflectors

Propulsion, energy collection, communication or habitation in space requires ever larger space structures for the exploration of our solar system and beyond. Due to the payload size restrictions of the current launch vehicles, deployable structures are the way to go to launch very large structures into orbit. This paper therefore presents the design and simulation of a tensegrity based structure with inflatable rigidizable tubes as compression struts. The literature review showed that inflatable structures are most promising for the development of deployable reflectors larger than twenty meters in diameter. Good compression performance and reliability can be achieved by employing rigidisable inflatable tubes. The concept presented in this paper will focus on the development and simulation of a one meter diameter hexagonal reflector substructure that can be easily expanded to larger diameters due to its modular design. The one meter diameter modular approach was chosen to be able to build a full size benchmark model to validate the numerical data in the future. Due to the fact that the tensegrity compression elements are not initiating at one specific location, a passive reaction gas inflation technique is proposed which makes the structure independent of any pumps or other active inflation devices. This paper will discuss the use of inflatable rigidizable elements and their counteraction with the rest of the tensegrity structure. Simulations have been undertaken to capture the deployment behaviour of the inflating tube while getting perturbated by the attached tensegrity tension cables. These simulations showed that the use of inflatable rigidisable struts in tensegrity assemblies can greatly decrease the system mass and stowed volume, especially for very large reflectors compared to conventional approaches

HEATED TOOLING FOR AEROSPACE COMPOSITES MANUFACTURE

The increasingly high capital investment required for large autoclaves, ovens and facilities for the processmg of large composite components creates a number of financial constraints for the development and manufacturing of larger composite aircraft products. This thesis has investigated the use of heated tooling as an alternative to the use of autoclave and oven curing. A design and development methodology for heated tools has been proposed while a number of heated tooling options have been identified and described. Three representative heated tool options using heater mats, electro-conductive textiles and wire heater elements have been evaluated. The curing capability of a prototype heated tool incorporating wire heater elements has been proved by carrying out a number of curing tests on RFI (Resin Fihn Infusion) laminates. The moulded laminates indicate that a 78-83% extent of cure is achieved prior to post-cure. The fibre and void content of cured laminates has also been verified through acid digestion and microscopy, where an acceptable fibre volume fraction (Vf) of 55-57% and a void content of less than 2% have been achieved. The usefulness of ID and 3D thermal Finite Element Analysis for the design and simulation of heated tooling has also been studied. A manufacturing and cost analysis study carried out has identified potential production implications, while the cost effectiveness of heated tooling compared to oven and autoclave processmg has been indicated. Cost reductions are noted in capital investments, operational costs and production set-up costs per part. The work described in this thesis gives valuable information for the implementation of heated tooling as a new processing method for aerospace composite products. The information can prove useful when considermg the processing options of large composite parts such as wing spars, fan cowl doors and wing skins.GKN Aerospace Service

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

Inflatable structures for Mars Base 10

A permanent manned settlement on the Martian surface requires the use of advanced technology concepts in order to become technically and financially feasible. The former developed Mars Base 10 concept incorporates novel ideas, increasing the feasibility of a continous human base on Mars. The most advanced feature of the MB10 design is the concept of increasing the habitable space of the Mars base once landed with an inflatable torus like structure. This paper gives an overview on the MB10 design and has its primary focus on the deployment of the inflatable structure. The deployment simulations show the final inflated shape of the MB10 concept on Mars from an un-inflated initial shape on Earth. The deployment strategy, simulations and rigidization techniques are discussed to provide a conceptual solution for large inflatable components of the MB10 habitat. Further applications of secondary inflatable smart structures are presented as well. These secondary structures are self deploying at the Martian ambient pressure which results in low storage volume and mass. These structures are well-suited to carry on for astronauts on EVAs for example

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected