Design and Analysis of SMA Woven Fabric

Shape Memory Alloys (SMAs) are often used for robotic, biomedical, and aerospace applications because of their unique ability to undergo large amounts of stress and strain during thermomechanical loading compared to traditional metals. While SMAs such as NiTi have been used in wire, plate, and tubular forms, NiTi as a woven dry fabric has yet to be analyzed for use as protective materials and actuators. Applications of SMA fabric as a “passive” material include shields, seatbelts, watchbands and window screens. Applications as an “active” material include robotic actuators, wearable medical and therapy devices, and self-healing shields and screens. This paper applies a macro-mechanical model from composites analysis to NiTi plain woven fabric to determine the effective elastic constants. The fabric model is based on actual weave geometry, including the presence of open gaps and wire cross-sectional area, and with the same diameter and alloy in the warp and weft. A woven NiTi ribbon has been manufactured (Figure 1) using a narrow weaving machine and has been tested in uniaxial tension. Planar fabric constants were measured at a range of temperatures. The analytically and experimentally derived constants for various weave patterns and cover factor combinations are presented and compared. It was determined that in uniaxial tension the fabric behaves like a collection of unidirectional wires, but has 78% of the rigidity, on average, across all test temperatures. This result is predicted by the fabric model with a 16% error, demonstrating that the proposed analytical model offers a useful tool for design and simulation of SMA fabrics.

Download Full-text

TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151428 ◽

1993 ◽

Vol 51 ◽

pp. 1118-1119

Author(s):

Pamela F. Lloyd ◽

Scott D. Walck

Keyword(s):

Thin Films ◽

Sample Preparation ◽

Room Temperature ◽

High Vacuum ◽

Pulsed Laser ◽

Ultra High Vacuum ◽

Wear Testing ◽

Preparation Technique ◽

Cross Sectional ◽

Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

Download Full-text

Intrinsic Self-Healing Epoxies in Polymer Matrix Composites (PMCs) for Aerospace Applications

Polymers ◽

10.3390/polym13020201 ◽

2021 ◽

Vol 13 (2) ◽

pp. 201

Author(s):

Stefano Paolillo ◽

Ranjita K. Bose ◽

Marianella Hernández Santana ◽

Antonio M. Grande

Keyword(s):

High Performance ◽

Polymer Matrix Composites ◽

Critical Issue ◽

General Description ◽

Self Healing ◽

Matrix Composites ◽

Testing Procedures ◽

Aerospace Applications ◽

Polymer Properties ◽

Healing Efficiency

This article reviews some of the intrinsic self-healing epoxy materials that have been investigated throughout the course of the last twenty years. Emphasis is placed on those formulations suitable for the design of high-performance composites to be employed in the aerospace field. A brief introduction is given on the advantages of intrinsic self-healing polymers over extrinsic counterparts and of epoxies over other thermosetting systems. After a general description of the testing procedures adopted for the evaluation of the healing efficiency and the required features for a smooth implementation of such materials in the industry, different self-healing mechanisms, arising from either physical or chemical interactions, are detailed. The presented formulations are critically reviewed, comparing major strengths and weaknesses of their healing mechanisms, underlining the inherent structural polymer properties that may affect the healing phenomena. As many self-healing chemistries already provide the fundamental aspects for recyclability and reprocessability of thermosets, which have been historically thought as a critical issue, perspective trends of a circular economy for self-healing polymers are discussed along with their possible advances and challenges. This may open up the opportunity for a totally reconfigured landscape in composite manufacturing, with the net benefits of overall cost reduction and less waste. Some general drawbacks are also laid out along with some potential countermeasures to overcome or limit their impact. Finally, present and future applications in the aviation and space fields are portrayed.

Download Full-text

A self-healing 3D woven fabric reinforced shape memory polymer composite for impact mitigation

Smart Materials and Structures ◽

10.1088/0964-1726/19/3/035007 ◽

2010 ◽

Vol 19 (3) ◽

pp. 035007 ◽

Cited By ~ 71

Author(s):

Jones Nji ◽

Guoqiang Li

Keyword(s):

Shape Memory ◽

Polymer Composite ◽

Shape Memory Polymer ◽

Woven Fabric ◽

Self Healing ◽

Impact Mitigation

Download Full-text

Structure optimization of woven fabric composites for improvement of mechanical properties using a micromechanics model of woven fabric composites and a genetic algorithm

Composites and Advanced Materials ◽

10.1177/26349833211006114 ◽

2021 ◽

Vol 30 ◽

pp. 263498332110061

Author(s):

Gunyong Hwang ◽

Dong Hyun Kim ◽

Myungsoo Kim

Keyword(s):

Mechanical Properties ◽

Genetic Algorithm ◽

Elastic Modulus ◽

Fiber Composite ◽

Woven Fabric ◽

Cross Sectional ◽

Micromechanics Model ◽

Woven Fabric Composites ◽

Fabric Composites ◽

Out Of Plane

This research aims to optimize the mechanical properties of woven fabric composites, especially the elastic modulus. A micromechanics model of woven fabric composites was used to obtain the mechanical properties of the fiber composite, and a genetic algorithm (GA) was employed for the optimization tool. The structure of the fabric fiber was expressed using the width, thickness, and wave pattern of the fiber strands in the woven fabric composites. In the GA, the chromosome string consisted of the thickness and width of the fill and warp strands, and the objective function was determined to maximize the elastic modulus of the composite. Numerical analysis showed that the longitudinal mechanical properties of the strands contributed significantly to the overall elastic modulus of the composites because the longitudinal property was notably larger than the transverse property. Therefore, to improve the in-plane elastic modulus, the resulting geometry of the composites possessed large volumes of related strands with large cross-sectional areas and small strand waviness. However, the numerical results of the out-of-plane elastic modulus generated large strand waviness, which contributed to the fiber alignment in the out-of-plane direction. The findings of this research are expected to be an excellent resource for the structural design of woven fabric composites.

Download Full-text

Design of self-healing catalysts for aircraft application

International Journal of Structural Integrity ◽

10.1108/ijsi-12-2017-0077 ◽

2018 ◽

Vol 9 (6) ◽

pp. 723-736 ◽

Cited By ~ 1

Author(s):

Elisa Calabrese ◽

Pasquale Longo ◽

Carlo Naddeo ◽

Annaluisa Mariconda ◽

Luigi Vertuccio ◽

...

Keyword(s):

Ruthenium Catalysts ◽

The Self ◽

Self Healing ◽

Catalytic Systems ◽

Content Type ◽

Aerospace Applications ◽

Healing Efficiency ◽

Relevant Role ◽

Aircraft Application

PurposeThe purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.Design/methodology/approachHere, a very detailed evaluation on the stereochemistry of two new ruthenium catalysts evidences the crucial role of the spatial orientation of phenyl groups in the N-heterocyclic carbene ligands in determining the temperature range within the curing cycles is feasible without deactivating the self-healing mechanisms (ring-opening metathesis polymerization reactions) inside the thermosetting resin. The exceptional activity and thermal stability of the HG2MesPhSyncatalyst, with the syn orientation of phenyl groups, highlight the relevant potentiality and the future perspectives of this complex for the activation of the self-healing function in aeronautical resins.FindingsThe HG2MesPhSyncomplex, with the syn orientation of the phenyl groups, is able to activate metathesis reactions within the highly reactive environment of the epoxy thermosetting resins, cured up to 180°C, while the other stereoisomer, with the anti-orientation of the phenyl groups, does not preserve its catalytic activity in these conditions.Originality/valueIn this paper, a comparison between the self-healing functionality of two catalytic systems has been performed, using metathesis tests and FTIR spectroscopy. In the field of the design of catalytic systems for self-healing structural materials, a very relevant result has been found: a slight difference in the molecular stereochemistry plays a key role in the development of self-healing materials for aeronautical and aerospace applications.

Download Full-text

A FEA Method for Mathematical Calculation and Prediction Analysis Cross-sectional Ovalization of Tubes under Rotary Straightening

Journal of Physics Conference Series ◽

10.1088/1742-6596/2083/4/042057 ◽

2021 ◽

Vol 2083 (4) ◽

pp. 042057

Author(s):

Ziqian Zhang ◽

Ying Zhong

Keyword(s):

Process Parameters ◽

Element Model ◽

Simulation Method ◽

Stress And Strain ◽

Cross Sectional ◽

Bending Deformation ◽

Deformation Stage ◽

Thin Walled Pipe ◽

Thin Walled ◽

Flattening Process

Abstract The section flattening phenomenon (namely Bazier effect) will occur in the large bending deformation stage of thin-walled pipe in the continuous straightening process. The maximum section flattening amount and the residual section flattening amount are important process parameters, which are the basis for calculating the subsequent process parameters of the flattening circle, and directly determine the roundness of the final pipe and the product quality. However, it is hard to be obtained by the theoretical or experimental methods. Therefore, based on the structure and process parameters of the leveler, a finite element model was built to simulate the section flattening process. Then, ANSYS/LS-DYNA software was used to dynamically simulate the bending flattening phenomenon of thin-walled pipe in the continuous straightening process, and the stress and strain nephographic of the flattening deformation zone was obtained. By recording the position curve of the key nodes in the preventing process, the section flattening amount of the thin-walled pipe in the large bending deformation stage in the continuous straightening process was determined. The simulation results show that the dynamic simulation method can effectively predict the section flattening of thin-walled pipe in the process of continuous straightening.

Download Full-text

Plasticity and Viscoplasticity

Metal Forming and the Finite-Element Method ◽

10.1093/oso/9780195044027.003.0007 ◽

1989 ◽

Author(s):

Shiro Kobayashi ◽

Soo-Ik Oh ◽

Taylan Altan

Keyword(s):

Uniaxial Tension ◽

Metal Forming ◽

Experimental Studies ◽

Plasticity Theory ◽

Cross Sectional Area ◽

Sectional Area ◽

Stress Strain ◽

Cross Sectional ◽

Theory Of Plasticity ◽

Classical Plasticity

The theory of plasticity describes the mechanics of deformation in plastically deforming solids, and, as applied to metals and alloys, it is based on experimental studies of the relations between stresses and strains under simple loading conditions. The theory described here assumes the ideal plastic body for which the Bauschinger effect and size effects are neglected. The theory also is valid only at temperatures for which recovery, creep, and thermal phenomena can be neglected. The basic theory of classical plasticity is described by Hill, and also in References, in addition to the books listed in Chap. 1. A concise description of the general plasticity theory necessary for metal forming is given in the book by Johnson et al.. In this chapter, certain important aspects of the theory are presented in order to elucidate the developments of the finite-element solutions of metal-forming problems discussed in this book. First, various measures of stress and strain are introduced. Then, the governing equations for plastic deformation and principles that are the foundations for the analysis are described. The extension of the theory of plasticity to time-dependent theory of viscoplasticity is outlined in Section 4.8. Particular references are made, in Sections 4.3 through 4.7, to the books by Hill and by Johnson and Mellor, and to the section on general plasticity theory in the book by Johnson et al.. The basic quantities that may be used to describe the mechanics of deformation when a body deforms from one configuration to another under an external load are the stress, strain, and strain-rate. Various measures of these quantities are defined, depending upon how closely formulations represent actual situations. Although it is not possible to provide the complete mathematical formulations in one-dimensional deformation, these measures are introduced for the case of simple uniaxial tension. Consider the uniaxial tension test of a round specimen whose initial length is l0 and cross-sectional area is A0. The specimen is stretched in the axial direction by the force P to the length l and the cross-sectional area A at time t, as shown in Fig. 4.1. The response of the material is recorded as the load-displacement curve, and converted to the stress-strain curve as shown in the figure. The deformation is assumed to be homogeneous until necking begins.

Download Full-text

Nanocomposites for Space Applications

Diverse Applications of Organic-Inorganic Nanocomposites - Advances in Mechatronics and Mechanical Engineering ◽

10.4018/978-1-7998-1530-3.ch008 ◽

2020 ◽

pp. 191-222

Author(s):

Rafael Vargas-Bernal ◽

Margarita Tecpoyotl-Torres

Keyword(s):

Electromagnetic Interference ◽

Hybrid Nanocomposites ◽

Space Environment ◽

Self Healing ◽

Two Dimensional ◽

Space Applications ◽

Aerospace Applications ◽

Structural Applications ◽

Two Dimensional Materials ◽

Carbon Based Nanomaterials

A review on the advances achieved in the last 25 years in the development of hybrid nanocomposites based on polymer matrix for aerospace applications is presented here. The chapter analyzes the state-of-the-art strategies used in the design of materials that support the different conditions of the space environment. These materials are aimed primarily at structural applications, electromagnetic interference shielding, self-sensing, and self-healing, although they are not restricted to these applications. The introduction of metallic, ceramic, carbon-based nanomaterials such as carbon nanotubes and graphene, as well as two-dimensional materials have been used with a successful impact. Despite the significant advances that have been reached, much work must be done to achieve complete reliability for all properties required to protect the systems against the hazardous conditions found in space. Therefore, futuristic visions of the actions that must be carried out are raised in this chapter.

Download Full-text