Impact performances of monoaxial knitted fabric composites

Fabric Composites ◽

Out Of Plane ◽

Weight Impact ◽

This study aims to investigate the impact performances of the monoaxial knitted fabric composites to evaluate the effect of straight yarns within the reinforcement knitted fabric. Monoaxial knitted fabric composites have enhanced in-plane properties and it is important to evaluate the effect of yarn insertion on the impact performances because knitted fabric composites are preferred due to their out-of-plane properties. Bending, impact and compression after impact (CAI) tests were performed on the composites reinforced with monoaxial rib knitted fabrics. The flexural properties, the peak force, the damage area and the energy absorption capabilities under drop weight impact loadings and the compression strength after impact of the composites were evaluated comparatively. The results indicated that the monoaxial rib knitted fabric reinforcement enhances the bending and CAI performances of the composites, but it causes detrimental effects on the impact performances of the composites. The use of yarn insertion for the enhancement of the composite performance necessitates considerate planning for an optimization between the in-plane and out-of-plane properties of the knitted fabric composites.

Damage Modes in Impact Loading of Glass Woven Fabric Composites

Advanced Composites Letters ◽

10.1177/096369359600500205 ◽

1996 ◽

Vol 5 (2) ◽

pp. 096369359600500 ◽

Cited By ~ 5

Author(s):

Yasunobu Hirai ◽

Hiroyuki Hamada ◽

Jang-Kyo Kim

Keyword(s):

Fibre Surface ◽

Woven Fabric ◽

Interface Debonding ◽

Matrix Composites ◽

Damage Area ◽

Impact Performance ◽

Woven Fabric Composites ◽

Fabric Composites ◽

The Impact ◽

Instrumented Impact Test

Instrumented impact test was used to assess the impact performance of E-glass woven fabric reinforced vinyl ester matrix composites. Evaluation of the damages with the aid of optical microscopy revealed substantial differences in the shape, mode and area of damage between the front and back surfaces of impact and between laminates with different fibre surface treatments. Apart from the extensive delamination in the central damage region, interface debonding occurred along the warp and weft directions in the surrounding regions near the back face of impact which contributed significantly to the total damage area of the laminate.

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

Effect of textile geometry on axisymmetric stretch forming of knitted fabric composites

10.1243/0954405001517720 ◽

2000 ◽

Vol 214 (4) ◽

pp. 333-337 ◽

Cited By ~ 4

Author(s):

T C Lim ◽

S Ramakrishna ◽

H M Shang

Keyword(s):

Reasonable Agreement ◽

Convex Surface ◽

Shell Height ◽

Sheet Forming ◽

Knitted Fabric ◽

Stretch Forming ◽

Knitted Fabrics ◽

Excellent Quality ◽

Tool Profile ◽

Fabric Composites

Plain weft-knitted fabrics are known for their excellent quality to stretch and drape around a convex surface without wrinkling. In recent years, sheet forming of knitted fabric composites has been investigated in view of promising future applications. In this paper a prediction of attainable shell height is proposed with reference to the textile geometry and the tool profile. Comparison between the measured and predicted shell heights shows reasonable agreement. The present analysis should provide a guideline for manufacturers in selecting the appropriate textile geometry for satisfactory stretch forming operations of knitted fabric composites.

Comparative Study on Fatigue Life of CFRP Composites with Damages

Fatigue of Aircraft Structures ◽

10.2478/fas-2019-0004 ◽

2019 ◽

Vol 2019 (11) ◽

pp. 28-38

Author(s):

Marta Baran ◽

Piotr Synaszko ◽

Janusz Lisiecki ◽

Sylwester Kłysz

Keyword(s):

Residual Strength ◽

Stress Ratio ◽

Fatigue Tests ◽

Equivalent Diameter ◽

Strength Tests ◽

Cfrp Composite ◽

Sinusoidal Shape ◽

Weight Impact ◽

AbstractIn this work, the compressive residual strength tests results, Compression After Impact (CAI), are presented. The specimens were made of carbon-epoxy prepreg E722-02 UHS 130-14. Two variants of specimens were tested: samples undamaged and samples with damage that was centrally introduced by a drop-weight impact, as per the ASTM D7136/7136M standard. An impactor with potential energy equal to 15J and the type of support required by the standard were used. The size of impacted damages, defined as an area of damage on a plane perpendicular to the impact direction, and the equivalent diameter were specified using the flash thermography method.The tests were performed using the fixtures manufactured according to the ASTM D7137/7137M standard. The specimens were compressed to determine the residual strength. This value was afterwards used to specify the force levels for the fatigue tests. The fatigue tests were carried out under force control – with a sinusoidal shape, stress ratio R equal to 0.1 and frequency f 1Hz. Maximum force in a loading cycle Pmax was being increased after each thousand of cycles N until its value was close to the residual strength determined in the previously mentioned tests. In this work, the following relationships were presented: force-displacement P-δ for both static and fatigue tests and displacement-loading cycles δ-N for fatigue tests.A method of conducting the fatigue tests of CFRP composite was proposed, in which both the CAI specimens and CAI fixture were used. This allowed researchers to accelerate making initial comparisons between the two groups of specimens with damages – grouped relative to the way of conditioning.

Low velocity impact and compression after impact behaviour of polyester pin-reinforced foam filled honeycomb sandwich panels

Journal of Sandwich Structures & Materials ◽

10.1177/1099636221998180 ◽

2021 ◽

pp. 109963622199818

Author(s):

RS Jayaram ◽

VA Nagarajan ◽

KP Vinod Kumar

Keyword(s):

Impact Damage ◽

Sandwich Panels ◽

Low Velocity Impact ◽

Low Velocity ◽

Velocity Impact ◽

Damage Area ◽

Honeycomb Sandwich ◽

Foam Filled ◽

Hybridization of sandwich panels and their different components have drawn huge attention due to the significant improvement in their attributes. Hybrid core of ‘Polyester Pin-reinforced Foam filled Honeycomb Sandwich panels’ (PFHS) were fabricated and compared with unreinforced ‘Foam filled Honeycomb Sandwich panels’ (FHS) in terms of low velocity impact and Compression After Impact (CAI) performance. The impact damage area was calculated by employing MATLAB image processing technique. Incorporating through thickness pins for connecting faces and core is an effectual way to improve interfacial bonding, specific bending stiffness and also imparts out of plane properties for sandwich panels. The low velocity impact tests performed on the sandwich panels revealed that the polyester pin reinforcement in foam filled honeycomb sandwich panel improved the load bearing capacity, total absorbed energy and reduced the impact damage area significantly. In CAI test, debond, wrinkling of face sheet, and buckling of face sheet and core are the major modes of failure. The addition of the pins enhanced the compressive strength for all the impact energy levels.

Effect of Fibre Bundle Structure on Stretch Forming Properties of Plain Weft-Knitted Fabric Composites

Advanced Composites Letters ◽

10.1177/096369359900800402 ◽

1999 ◽

Vol 8 (4) ◽

pp. 096369359900800

Author(s):

T.C. Lim ◽

S. Ramakrishna ◽

H.M. Shang

Keyword(s):

Fibre Bundle ◽

Knitted Fabric ◽

Shells Of Revolution ◽

Stretch Forming ◽

Composite Sheet ◽

Knitted Fabrics ◽

Weft Knitted Fabric ◽

Fabric Composite ◽

Fabric Composites ◽

Bundle Structure

Knitted fabrics are known for their excellent stretchability and their flat composites have recently been shown to be easily stretch-formed into thin shells of revolution. In this paper, the stretch-forming properties are being investigated with due attention given to the fibre bundle loop structure. The capability of a plain weft-knitted fabric composite sheet to be stretch-formed is elucidated with reference to the fibre bundle structure.

Review of Through-the-Thickness Reinforced z-Pinned Composites

Journal of Composites Science ◽

10.3390/jcs4010031 ◽

2020 ◽

Vol 4 (1) ◽

pp. 31 ◽

Cited By ~ 2

Author(s):

Vassilis Kostopoulos ◽

Nikolaos Sarantinos ◽

Stavros Tsantzalis

Keyword(s):

Mechanical Properties ◽

Composite Laminates ◽

Fatigue Loading ◽

Mode I ◽

Mode Ii ◽

Impact Properties ◽

Out Of Plane ◽

Plane Direction ◽

This work reviews the effects of z-Pins used in composite laminates as through-the-thickness reinforcement to increase the composite’s properties in the out-of-plane direction. The paper presents the manufacture and microstructure of this reinforcement type while also incorporating the impact of z-Pins on the mechanical properties of the composite. Mechanical properties include tensile, compression, flexure properties in static, dynamic and fatigue loads. Additionally, mode I and mode II properties in both static and fatigue loading are presented, as well as hygrothermal, impact and compression after impact properties.

Mechanical Behavior of Highly-Flexible Elastomeric Composites with Knitted-Fabric Reinforcement

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.504-506.1123 ◽

2012 ◽

Vol 504-506 ◽

pp. 1123-1128

Author(s):

Burak Bekisli ◽

Johann Pancrace ◽

Herman F. Nied

Keyword(s):

Composite Structures ◽

Mechanical Performance ◽

Plane Deformation ◽

Matrix Material ◽

Knitted Fabric ◽

Knitted Fabrics ◽

Fabric Reinforcement ◽

Energy Impact ◽

The Matrix ◽

Impact Absorption

This paper examines critical issues associated with the fabrication and forming of highly-flexible polymeric composites, reinforced with knitted-fabric structures. Knitted-fabric reinforcements have not generally been preferred over more traditional woven reinforcements in high-performance composites, mainly because of their lower stiffness/strength performance when embedded in a rigid, thermosetting matrix material. However, with their unique formability, knitted fabrics promise great potential in applications where large deformation of the structure is desirable; such as energy/impact absorption and forming applications. One very attractive feature of knitted composite materials, is the large displacements that the underlying knitted fabric can potentially undergo before exhibiting a significant increase in stiffness. The unusual extensional behavior of knit fabric is attributed to the fact that the fibers are more-or-less free to slide over each other before the yarns become highly oriented, eventually “locking” in a packed formation. When the loops become highly elongated, the knit fabric achieves its maximum resistance to in-plane deformation, and exhibits a stiffness closely related to the elastic stiffness of the straightened fiber/yarn bundles. The unique formability of knitted fabrics is mainly due to this yarn movement. The highly “stretchable” behavior of knitted textile reinforcement materials can be used to great advantage in thermoforming composite structures. In order to fully utilize the exceptional stretch properties of the knitted-fabric, the matrix material should be able to deform at least as much as the fabric, and the knitted yarn movements need to be restricted by the matrix as little as possible. In this study, a multi-level finite element procedure was developed to analyze and control the deformation characteristics of plain weft knit reinforced composites. A database of mechanical properties for various knit geometries was obtained. Using these results, it is shown that carefully “tailored” knit fabric reinforcement can be used to improve mechanical performance and facilitate polymer forming processes, such as thermoforming. In this study, elastomeric materials such as polyurea and thermoplastic elastomer (TPE) were used to fabricate composites with knitted-fabric. Two different types of arrangements were experimentally studied: knitted fabric embedded in the elastomer and a sandwich of knitted fabric between elastomeric skins. It is shown that by fully utilizing the high stretchability of the knitted fabric reinforcements, attractive material properties can be obtained especially for energy/impact absorption and forming applications. The improvement of thermoforming process stability with the use of carefully tailored knitted fabric reinforcements is also presented.

Investigation of the impact of externally applied out-of-plane stress on Ferroelectric FET

IEEE Electron Device Letters ◽

10.1109/led.2020.3049093 ◽

2021 ◽

pp. 1-1

Author(s):

Yefan Liu ◽

Sergiu Clima ◽

Gaspard Hiblot ◽

Philippe Matagne ◽

Mihaela Loana Popovici ◽

...

Keyword(s):

Plane Stress ◽

Out Of Plane ◽

Resistless Patterning of Magnetic Storage Media Using Ion Projection Structuring

MRS Proceedings ◽

10.1557/proc-705-y3.4 ◽

2001 ◽

Vol 705 ◽

Cited By ~ 2

Author(s):

A. Dietzel ◽

R. Berger ◽

H. Grimm ◽

C. Schug ◽

W. H. Bruenger ◽

...

Keyword(s):

Process Development ◽

Ion Beam ◽

Silicon On Insulator ◽

Magnetic Storage ◽

Magnetic Islands ◽

Superlattice Structure ◽

Head Positioning ◽

Out Of Plane ◽

Set Up ◽

AbstractCo/Pt thin film multilayers with strong perpendicular anisotropy and out-of-plane coercivities of 5-11 kOe were magnetically altered in areas of local ion beam interaction. The ion irradiations were performed by ion projection through silicon stencil masks fabricated by silicon on insulator (SOI) membrane technology. The ion projector at the Fraunhofer Institute for Silicon Technology (ISiT) was operated at 73 keV ion energy and with a 8.7- fold demagnification. After exposure to 3 × 1014Ar+/ cm2 magnetic islands smaller than 100 nm in diameter were resolved in the Co/Pt multilayersby means of magnetic force microscopy. The impact of different ion species (He+, Ar+ and Xe+) and ion energies (10 – 200 keV) on the multilayer structure was evaluated using Monte Carlo simulations. The ballistic interface intermixing was used to predict magnetic coercivity changes for various irradiation conditions. The simulations revealed that with 73 keV Ar+ and Xe+ ions the irradiation dose could be reduced by a factor of 100 and 400 respectively in comparison to 73 keV He+which was verified in the experiments. X-ray reflectivity measurements confirmed that the Co/Pt superlattice structure is slightly weakened during the irradiation and that the surface smoothness of the media is preserved. Using the Ion Projection Process Development Tool (PDT) at IMS-Vienna concentric data tracks including head positioning servo informations were patterned onto a 1” IBM microdrive™ glass disk which was coated with Co/Pt multilayers. In a single exposure step several tracks within an exposure field of 17 mm in diameter were structured by 2 × 1015He+/ cm2 at 45 keV using a 4- fold demagnification set-up.

The impact of different proportions of knitting elements on the resistive properties of conductive fabrics

Textile Research Journal ◽

10.1177/0040517518758003 ◽

2018 ◽

Vol 89 (5) ◽

pp. 881-890 ◽

Cited By ~ 3

Author(s):

Su Liu ◽

Yanping Liu ◽

Li Li

Keyword(s):

Contact Resistance ◽

Reference Source ◽

Wearable Electronics ◽

Electronic Textiles ◽

Knitted Fabrics ◽

Conductive Yarns ◽

Key Factor ◽

Resistive Networks ◽

The Impact ◽

Resistive Property

Conductive yarn is the key factor in fabricating electronic textiles. Generally, three basic fabric production methods (knit, woven, and non-woven) combined with two finishing processes (embroidery and print) are adopted to embed conductive yarns into fabrics to achieve flexible electronic textiles. Conductive yarns with knit structure are the most flexible and effective form of electronic textiles. Electronic textiles present many advantages over conventional electronics. However, in the process of commercialization of conductive knitted fabrics, it is a great challenge to control the complicated resistive networks in conductive knitted fabrics for the purpose of cost saving and good esthetics. The resistive networks in conductive knitted fabrics contain length-related resistance and contact resistance. The physical forms of conductive yarns in different fabrication structures can be very different and, thus, the contact resistance varies greatly in different fabrics. So far, study of controlling the resistive property of conductive fabrics has not been conducted. Therefore, establishing a systematic method for the industry as a reference source to produce wearable electronics is in great demand. During the industrialization of conductive knitted fabrics, engineers can estimate the resistive property of the fabric in advance, which makes the production process more effective and cost efficient. What is more, the resistive distribution in the same area of knitted fabrics can be fully controlled.