SEARCH · Search NASA

Results for “Composite design”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records

All sources NASA NTRS DOE OSTI

NASA NTRS1997

Probabilistic Composite Design

Probabilistic composite design is described in terms of a computational simulation. This simulation tracks probabilistically the composite design evolution from constituent materials, fabrication process, through composite mechanics and structural components. Comparisons with experimental data are provided to illustrate selection of probabilistic design allowables, test methods/specimen guidelines, and identification of in situ versus pristine strength, For example, results show that: in situ fiber tensile strength is 90% of its pristine strength; flat-wise long-tapered specimens are most suitable for setting ply tensile strength allowables: a composite radome can be designed with a reliability of 0.999999; and laminate fatigue exhibits wide-spread scatter at 90% cyclic-stress to static-strength ratios.

Chamis, Christos C.↗

NASA NTRS1997

Probabilistic Approaches: Composite Design

Probabilistic composite design is described in terms of a computational simulation. This simulation tracks probabilistically the composite design evolution from constituent materials, fabrication process through composite mechanics, and structural component. Comparisons with experimental data are provided to illustrate selection of probabilistic design allowables, test methods/specimen guidelines, and identification of in situ versus pristine strength. For example, results show that: in situ fiber tensile strength is 90 percent of its pristine strength; flat-wise long-tapered specimens are most suitable for setting ply tensile strength allowables; a composite radome can be designed with a reliability of 0.999999; and laminate fatigue exhibits wide spread scatter at 90 percent cyclic-stress to static-strength ratios.

Chamis, Christos C.↗

NASA NTRS1995

Effects of Yarn Crimping on Braided Composite Design Allowables

Braided composite materials are currently being evaluated for wing skin stiffeners on commercial aircraft. These carbon-fiber/epoxy materials allow for low-cost manufacturing while maintaining high strength-to-weight and stiffness-to-weight ratios. The proposed braid architecture consists of axial carbon fiber yarns and braider carbon fiber yarns making 60 deg to 70 deg angles with respect to the axial yarns. These 2-D triaxial braids are produced as long, continuous tubes, which are flattened, cut, and stacked to produce the desired part thickness and shape. When infiltrated with epoxy resin and cured under a compaction pressure, the fiber yarns become crimped, allowing for higher fiber packing. Although high fiber packing is desirable, yarn crimping (especially in the axial fiberyarns) is undesirable. Significant axial yarn crimp angles (greater than 10 deg) have been measured in braided composites. Comparable levels of crimping have been found to produce significant compressive strength reductions in laminated composites consisting of planar fiber sheets. Thus, axial yarn crimping is suspected of producing significant reductions in compressive strength allowables for braided composites. The objective of this research is to quantify the reduction in compressive strength as a function of axial yarn crimp severity. Since crimp severity can be reduced by lowering the compaction pressure during curing, the resulting compressive strengths may be used to determine optimum processing conditions. A 'cure-on-the-loom' manufacturing process was developed to produce braided composites with controlled levels of crimping. This method allowed for controlled levels of tension to be placed on the axial yarns and maintained during the curing process. With increasing tension, the crimp severity in the axial yarns was reduced. Thus, varying crimp severities were produced ranging from conventional levels (greater than 10 deg) to virtually straight axial yarns. Test results indicate that a 30% increase in compressive strength is obtainable by eliminating axial yarn crimping. Further compression testing is underway to quantify the relationship between crimp severity and compressive strength. Additional testing is planned to investigate the effect of crimping on the open-hole compressive strength, often considered a more significant design allowable.

Adams, Dan↗

NASA NTRS1986

Intraply Hybrid Composite Design

Several theoretical approaches combined in program. Intraply hybrid composites investigated theoretically and experimentally at Lewis Research Center. Theories developed during investigations and corroborated by attendant experiments used to develop computer program identified as INHYD (Intraply Hybrid Composite Design). INHYD includes several composites micromechanics theories, intraply hybrid composite theories, and integrated hygrothermomechanical theory. Equations from theories used by program as appropriate for user's specific applications.

Chamis, C. C.↗

NASA NTRS2001

The effects of aberrations (low order and quilting) on the performance of the all-composite design for the Herschel Space Observatory

The effects of specific aberrations on the optical performance of the all-composite design for the Herschel Space Observatory are examined. A review of the all-composite design for the large aperture (3.5 m) telescope that satisfies the target specifications is presented. Cryogenic experiments with carbon fiber reinforced polymer (CFRP) 2 m demonstration mirror have yielded empirical bounds on the high-and low-order spatial frequency aberrations that will be anticipated in the full 3.5 m Ritchey-Chretien telescope design. Detailed analysis is presented on the effect of the low order aberrations of the primary mirror on the system wavefront error and encircled energy. Predictable limits of correction via low order shaping of the secondary mirror are described. The impact of higher order surface errors on the encircled energy and the stray light will also be presented. Comments are made regarding the impact of the optical prescription and CRFP design on flight telescope testing.

energy↗

NASA NTRS1981

Computer code for intraply hybrid composite design

A computer program is described for intraply hybrid composite design (INHYD). The program includes several composite micromechanics theories, intraply hybrid composite theories, and a hygrothermomechanical theory. These theories provide INHYD with considerable flexibility and capability which the user can exercise through several available options. Key features and capabilities of INHYD are illustrated through selected samples.

Chamis, C. C.↗

NASA NTRS2007

Open-Lattice Composite Design Strengthens Structures

Advanced composite materials and designs could eventually be applied as the framework for spacecraft or extraterrestrial constructions for long-term space habitation. One such structure in which NASA has made an investment is the IsoTruss grid structure, an extension of a two-dimensional "isogrid" concept originally developed at McDonnell Douglas Astronautics Company, under contract to NASA's Marshall Space Flight Center in the early 1970s. IsoTruss is a lightweight and efficient alternative to monocoque composite structures, and can be produced in a manner that involves fairly simple techniques. The technology was developed with support from NASA to explore space applications, and is garnering global attention because it is extremely lightweight; as much as 12 times stronger than steel; inexpensive to manufacture, transport, and install; low-maintenance; and is fully recyclable. IsoTruss is expected to see application as utility poles and meteorological towers, for the aforementioned reasons and because its design offers superior wind resistance and is less susceptible to breaking and woodpeckers. Other applications, such as reinforcement for concrete structures, stand-alone towers, sign supports, prostheses, irrigation equipment, and sporting goods are being explored

Source record↗

NASA NTRS1982

Sensitivity analysis results of the effects of various parameters on composite design

Sensitivity analysis results are presented to assess the effects of a multitude of important parameters on fiber composite design and structural response. These results were obtained by using optimum design procedures in conjunction with sensitivity analyses. Sensitivity analyses were performed to assess the effects on composite optimum design and structural response of parameters such fiber transverse and shear properties, in situ matrix elastic and strength properties, correlation coefficients used in composite micromechanics and in combined strength predictions, processing variables, and perturbations of loading conditions. The results show that matrix properties, fiber volume ratio and small perturbations of the loading conditions have significant effects on certain composite structural responses. The remaining parameters have negligible effect.

Chamis, C. C.↗

NASA NTRS1981

Computer code for intraply hybrid composite design

A computer program has been developed and is described herein for intraply hybrid composite design (INHYD). The program includes several composite micromechanics theories, intraply hybrid composite theories and a hygrothermomechanical theory. These theories provide INHYD with considerable flexibility and capability which the user can exercise through several available options. Key features and capabilities of INHYD are illustrated through selected samples.

Chamis, C. C.↗

NASA NTRS1983

INHYD: Computer code for intraply hybrid composite design. A users manual

A computer program (INHYD) was developed for intraply hybrid composite design. A users manual for INHYD is presented. In INHYD embodies several composite micromechanics theories, intraply hybrid composite theories, and an integrated hygrothermomechanical theory. The INHYD can be run in both interactive and batch modes. It has considerable flexibility and capability, which the user can exercise through several options. These options are demonstrated through appropriate INHYD runs in the manual.

Chamis, C. C.↗

NASA NTRS2006

Simulated Data for High Temperature Composite Design

The paper describes an effective formal method that can be used to simulate design properties for composites that is inclusive of all the effects that influence those properties. This effective simulation method is integrated computer codes that include composite micromechanics, composite macromechanics, laminate theory, structural analysis, and multi-factor interaction model. Demonstration of the method includes sample examples for static, thermal, and fracture reliability for a unidirectional metal matrix composite as well as rupture strength and fatigue strength for a high temperature super alloy. Typical results obtained for a unidirectional composite show that the thermal properties are more sensitive to internal local damage, the longitudinal properties degrade slowly with temperature, the transverse and shear properties degrade rapidly with temperature as do rupture strength and fatigue strength for super alloys.

Chamis, Christos C.↗

NASA NTRS1988

Simplified procedures for designing composite bolted joints

Simplified procedures are described to design and analyze single and multi-bolt composite joints. Numerical examples illustrate the use of these methods. Factors affecting composite bolted joints are summarized. References are cited where more detailed discussion is presented on specific aspects of composite bolted joints. Design variables associated with these joints are summarized in the appendix.

Chamis, Christos C.↗

NASA NTRS1990

Simplified procedures for designing composite bolted joints

Chamis, Christos C.↗

NASA NTRS1989

Involute composite design evaluation using global design sensitivity derivatives

An optimization capability for involute structures has been developed. Its key feature is the use of global material geometry variables which are so chosen that all combinations of design variables within a set of lower and upper bounds correspond to manufacturable designs. A further advantage of global variables is that their number does not increase with increasing mesh density. The accuracy of the sensitivity derivatives has been verified both through finite difference tests and through the successful use of the derivatives by an optimizer. The state of the art in composite design today is still marked by point design algorithms linked together using ad hoc methods not directly related to a manufacturing procedure. The global design sensitivity approach presented here for involutes can be applied to filament wound shells and other composite constructions using material form features peculiar to each construction. The present involute optimization technology is being applied to the Space Shuttle SRM nozzle boot ring redesigns by PDA Engineering.

Hart, J. K.↗

NASA NTRS2026

Evaluating Energy Absorption Methods for Integrated Composite Seat Designs

Composite materials have become ubiquitous in the aerospace industry due to their exceptionally light weight and high strength characteristics, as well as their unique ability to be engineered and tailored to meet specific loading conditions and performance requirements. These advanced materials offer superior strength-to-weight ratios compared to traditional metallic materials, making them particularly valuable in weight-critical aerospace applications where every pound saved translates to improved efficiency and performance. In currently operating fleets of commercial and military aircraft, composite materials have been successfully applied to critical structural components, including primary load-bearing elements such as the fuselage sections and flooring structures, which must withstand significant in-flight loads and provide passenger safety. Additionally, these materials have been specifically tailored and optimized for aerodynamic components such as wings and tail assemblies, where their ability to be molded into complex shapes while maintaining structural integrity is particularly advantageous. The application of composite materials extends beyond primary structural elements into the realm of internal cabin components, most notably in innovative seat designs where weight reduction and structural integration are paramount concerns. Modern composite seat structures can be designed to integrate multiple functions, including structural support, comfort features, and safety systems, all while maintaining the lightweight characteristics essential for aircraft performance.

Digital image correlation↗

NASA NTRS1992

Designing Composite Structural Components

Report summarizes procedures for design of structural components made of fiber/matrix composite materials and of joints between such components. Summary presented by way of example design cases, using typical numerical values and showing typical results. Simplified form of applicable step-by-step design procedure, suitable for preliminary design, presented for each case. References to detailed descriptions in literature provided.

Murthy, P. L. N.↗

NASA NTRSDate not supplied

4pPA1 - Turbulence Effects on Shaped Booms: Central Composite Design of Modeled Atmospheric Turbulence Parameters for Sonic Boom Propagation

Propagation of sonic booms through turbulence reduces mean sonic boom perception metric levels and also causes considerable variability. NASA’s PCBoom suite of sonic boom acoustic propagation modules includes an approximate method for accounting for the effects of turbulence on traditional N-wave sonic booms. The current implementation is ineffective for shaped sonic booms or low-booms, and it also has limited values for turbulence and ambient input parameters. NASA’s future X-59 low-boom community noise surveys require an accurate estimate of the effects of turbulence in regions across the USA, so the module must be improved. This work presents the methods of selecting which ambient and turbulence parameters should be included in an improved PCBoom turbulence module. Turbulence and ambient data were collected from two atmospheric model databases, the Climate Forecast System Version 2 and European Centre for Medium-Range Weather Forecast Reanalysis Version 5 (ERA5), hourly from 7 AM to 7 PM local time for 10 years at 19 locations across the USA. A fully-factorial propagation analysis using these parameters would be exceedingly computationally expensive. Instead, a central composite design was chosen resulting in 45 combinations of ambient and turbulence parameters. These 45 cases effectively sample the space balancing computational burden.

turbulence↗

NASA NTRS2026

Thermoplastic Matrix Composite Design for Cryotanks Using Multiscale Modeling and Bayesian Optimization

Designing lightweight, robust cryogenic storage tanks is critical for future launch vehicles, in-space propellant storage, and hydrogen powered aircraft. This work presents a multiscale modeling and Bayesian optimization framework for the design of thermoplastic matrix composite cryotanks. Molecular dynamics simulations are first used to determine temperature-dependent constituent properties for candidate thermoplastic matrices, which are homogenized to the lamina scale using NASA’s Multiscale Analysis Tool (NASMAT). These lamina properties, in combination with laminate family generation rules, are evaluated in HyperX structural optimization software to identify stacking sequences that meet all cryogenic load requirements. A Bayesian optimization framework is applied, with HyperX in the loop (via the HyperX API) to efficiently search across material and laminate design variables, yielding an optimized cryotank configuration with significant reductions in design cycle time compared to exhaustive search approaches.

thermoplastics↗