Mechanical Performance Under Various Conditions of 3D Printed Polylactide Composites With Natural Fibers

AbstractIn the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by fused deposition modeling were tested. The effect of fiber type, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Differential scanning calorimetry were employed to analyze crystallization behavior of composite. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different levels of infilling result in a similar level of reduction in the properties. However, the addition of natural fillers resulted in a slightly lower drop than the lowered infilling rate − 40% and 50% for tensile strength, respectively. Moreover, it was found that, composites made of PLA are more sensitive to high temperatures than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Importantly, in the case of a brittle material such as PLA, the impact strength has been improved by 50% for composites with cork particles and other lignocellulosic composites remained at the same level as for resin. Generally, the thermal treatment of composites increased the degree of crystallinity of the materials, as reflected in the higher results of mechanical tests.

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Preparation and Performance Evaluation of Duotone 3D-Printed Polyetheretherketone as Oral Prosthetic Materials: A Proof-of-Concept Study

Polymers ◽

10.3390/polym13121949 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1949

Author(s):

Ling Ding ◽

Wei Lu ◽

Jiaqi Zhang ◽

Chuncheng Yang ◽

Guofeng Wu

Keyword(s):

Titanium Dioxide ◽

Performance Evaluation ◽

Mechanical Performance ◽

Mechanical Tests ◽

Flexural Properties ◽

Proof Of Concept ◽

Tooth Color ◽

Dental Application ◽

3D Printed ◽

And Performance

Literature has reported the successful use of 3D printed polyetheretherketone (PEEK) to fabricate human body implants and oral prostheses. However, the current 3D printed PEEK (brown color) cannot mimic the vivid color of oral tissues and thus cannot meet the esthetical need for dental application. Therefore, titanium dioxide (TiO2) and ferric oxide (Fe2O3) were incorporated into PEEK to prepare a series of tooth-color and gingival-color PEEK composites in this study. Through color measurements and mechanical tests, the color value and mechanical performance of the 3D printed PEEK composites were evaluated. In addition, duotone PEEK specimens were printed by a double nozzle with an interface between tooth-color and gingival-color parts. The mechanical performance of duotone PEEK with two different interfaces (horizontal and vertical) was investigated. With the addition of TiO2 and Fe2O3, the colors of 3D printed PEEK composites become closer to that of dental shade guides. 3D printed PEEK composites generally demonstrated superior tensile and flexural properties and hence have great potential in the dental application. In addition, duotone 3D printed PEEK with a horizontal interfacial orientation presented better mechanical performance than that with a vertical one.

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Development of Banana/Coir Natural Fibers Reinforced Polypropylene Hybrid Composites: The Effect of MA-g-PP (Maleic Anhydride Grafted Polypropylene) on Mechanical Properties and Thermal Properties

Nano Hybrids and Composites ◽

10.4028/www.scientific.net/nhc.32.85 ◽

2021 ◽

Vol 32 ◽

pp. 85-97

Author(s):

Gunturu Bujjibabu ◽

Vemulapalli Chittaranjan Das ◽

Malkapuram Ramakrishna ◽

Konduru Nagarjuna

Keyword(s):

Mechanical Properties ◽

Impact Strength ◽

Coupling Agent ◽

Mechanical Performance ◽

Hybrid Composites ◽

Natural Fibers ◽

Mechanical Tests ◽

Coir Fiber ◽

Banana Fiber ◽

C Fibers

Banana/Coir fiber reinforced polypropylene hybrid composites was formulated by using twin screw extruder and injection molding machine. Specimens were prepared untreated and treated B/C Hybrid composites with 4% and 8% of MA-g-PP to increase its compatibility with the polypropylene matrix. Both the without MA-g-PP and with MA-g-PP B/C hybrid composites was utilized and three levels of B/C fiber loadings 15/5, 10/10 and 5/15 % were used during manufacturing of B/C reinforced polypropylene hybrid composites. In this work mechanical performance (tensile, flexural and impact strengths) of untreated and treated (coupling agent) with 4% and 8% of MA-g-PP B/C fibers reinforced polypropylene hybrid composite have been investigated. Treated with MA-g-PP B/C fibers reinforced specimens explored better mechanical properties compared to untreated B/C fibers reinforced polypropylene hybrid composites. Mechanical tests represents that tensile, flexural and impact strength increases with increase in concentration of coupling agent compared to without coupling agent MA-g-PP hybrid composites . B/C fibers reinforced polymer composites exhibited higher tensile, flexural and impact strength at 5% of Banana fiber, 15% of fiber Coir in the presence of 8% of MA-g-PP compared to 4% of MA-g-PP and untreated hybrid composites. The percentage of water absorption in the B/C fibers reinforced polypropylene hybrid composites resisted due to the presence of coupling agent MA-g-PP and thermogravimetry analysis (TGA) also has done.

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Thermally Induced Mechanical Response of Metal Foam During Laser Forming

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4038995 ◽

2018 ◽

Vol 140 (4) ◽

Cited By ~ 7

Author(s):

Tizian Bucher ◽

Adelaide Young ◽

Min Zhang ◽

Chang Jun Chen ◽

Y. Lawrence Yao

Keyword(s):

Temperature Gradient ◽

Mechanical Response ◽

Metal Foam ◽

Mechanical Performance ◽

Image Correlation ◽

Laser Forming ◽

Experimental Proof ◽

Thermally Induced ◽

The Impact ◽

Different Levels

To date, metal foam products have rarely made it past the prototype stage. The reason is that few methods exist to manufacture metal foam into the shapes required in engineering applications. Laser forming is currently the only method with a high geometrical flexibility that is able to shape arbitrarily sized parts. However, the process is still poorly understood when used on metal foam, and many issues regarding the foam's mechanical response have not yet been addressed. In this study, the mechanical behavior of metal foam during laser forming was characterized by measuring its strain response via digital image correlation (DIC). The resulting data were used to verify whether the temperature gradient mechanism (TGM), well established in solid sheet metal forming, is valid for metal foam, as has always been assumed without experimental proof. Additionally, the behavior of metal foam at large bending angles was studied, and the impact of laser-induced imperfections on its mechanical performance was investigated. The mechanical response was numerically simulated using models with different levels of geometrical approximation. It was shown that bending is primarily caused by compression-induced shortening, achieved via cell crushing near the laser irradiated surface. Since this mechanism differs from the traditional TGM, where bending is caused by plastic compressive strains near the laser irradiated surface, a modified temperature gradient mechanism (MTGM) was proposed. The densification occurring in MTGM locally alters the material properties of the metal foam, limiting the maximum achievable bending angle, without significantly impacting its mechanical performance.

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Mechanical Performance of Unstitched and Silk Fiber-Stitched Woven Kenaf Fiber-Reinforced Epoxy Composites

Materials ◽

10.3390/ma13214801 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4801

Author(s):

Yasir Khaleel Kirmasha ◽

Mohaiman J. Sharba ◽

Zulkiflle Leman ◽

Mohamed Thariq Hameed Sultan

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Mechanical Performance ◽

Mechanical Test ◽

Natural Fibers ◽

Silk Fiber ◽

Epoxy Composites ◽

Test Results ◽

The Impact ◽

Woven Kenaf

Fiber composites are known to have poor through-thickness mechanical properties due to the absence of a Z-direction binder. This issue is more critical with the use of natural fibers due to their low strength compared to synthetic fibers. Stitching is a through-thickness toughening method that is used to introduce fibers in the Z-direction, which will result in better through-thickness mechanical properties. This research was carried out to determine the mechanical properties of unstitched and silk fiber-stitched woven kenaf-reinforced epoxy composites. The woven kenaf mat was stitched with silk fiber using a commercial sewing machine. The specimens were fabricated using a hand lay-up method. Three specimens were fabricated, one unstitched and two silk-stitched with deferent stitching orientations. The results show that the stitched specimens have comparable in-plane mechanical properties to the unstitched specimens. For the tensile mechanical test, stitched specimens show similar and 17.1% higher tensile strength compared to the unstitched specimens. The flexural mechanical test results show around a 9% decrease in the flexural strength for the stitched specimens. On the other hand, the Izod impact mechanical test results show a significant improvement of 33% for the stitched specimens, which means that stitching has successfully improved the out-of-plane mechanical properties. The outcome of this research indicates that the stitched specimens have better mechanical performance compared to the unstitched specimens and that the decrease in the flexural strength is insignificant in contrast with the remarkable enhancement in the impact strength.

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Fibre-Cement Paste Transition Zone

MRS Proceedings ◽

10.1557/proc-370-479 ◽

1994 ◽

Vol 370 ◽

Author(s):

Vahan Agopyan ◽

Holmer Savastano

Keyword(s):

Transition Zone ◽

Mechanical Performance ◽

Mechanical Tests ◽

Polypropylene Fibres ◽

Impact Performance ◽

The Matrix ◽

Vegetable Fibre ◽

Electron Image ◽

Backscattered Electron ◽

The Impact

AbstractThe characteristics of fibres and paste of ordinary Portland cement transition zone are analysed and correlated to the mechanical properties of the produced composites. The water-cement ratio of the matrix varies from 0.30 to 0.46 and the age of the specimens varies from 7 to 180 days. Composites of vegetable fibres (coir, sisal and malva) are compared with those of chrysotile asbestos and polypropylene fibres. The analysis is made by backscattered electron image (BSEI) and energy dispersive spectroscopy (EDS). Mechanical tests evaluate the composite tensile strength and ductility.Mainly for vegetable fibre composites the transition zone is porous, cracked and rich in calcium hydroxide macrocrystals. These results are directly associated with the fibre-matrix bonding and with the composite mechanical performance. Further studies considering the impact performance of the composites compare the porosity of the transition zone with the toughness of the composites.

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Adhesives for increasing the bonding strength of in situ manufactured metal-composite joints

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407020965759 ◽

2020 ◽

pp. 095440702096575

Author(s):

Robert Thomas ◽

Fabian Fischer ◽

Maik Gude

Keyword(s):

Bonding Strength ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Storage Conditions ◽

Mechanical Tests ◽

Metal Composite ◽

Scanning Calorimetry ◽

Lap Shear ◽

Glass Fibre Reinforced ◽

Metallic Parts

In this present work, the potential of metallic parts, locally reinforced with a continuous glass fibre reinforced thermoset material, pre-impregnated with an epoxy matrix (prepreg), was evaluated by differential scanning calorimetry (DSC), single-lap shear tests and 3-point bending tests of a metal-composite hybrid hat profile. This technology is evaluated regarding an automotive use case, the DSC experiments in combination with moulding trials have proven curing times below 30 s for a moulding temperature of 180°C. A bonding strength of 13.5 MPa was characterized for a co-cured fibre-reinforced plastic (frp) onto a metallic joining partner. By additionally introducing an epoxy glue film as a bonding agent, which is co-cured together with the frp, the bonding strength can be increased significantly up to 25.4 MPa at the expense of the curing time. The mechanical tests on the hybrid hat profile have shown an increase of energy absorption compared with non-reinforced hat profiles. Here, also an additional glue film extends the performance regarding a co-cured plastic reinforcement without glue film. The influence of the storage conditions of the uncured prepreg materials on the mechanical performance was evaluated by a simulated physical ageing at elevated temperatures, followed by a mechanical characterization of the bonding strength and part performance. Also the effect of different testing temperatures and testing velocities on the capability of the metal-composite hybrid part is illustrated.

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Assessment of mechanical strength of nano silica concrete (NSC) subjected to elevated temperatures

Journal of Structural Fire Engineering ◽

10.1108/jsfe-10-2017-0041 ◽

2019 ◽

Vol 10 (1) ◽

pp. 90-109 ◽

Cited By ~ 4

Author(s):

Hala Mohamed Elkady ◽

Ahmed M. Yasien ◽

Mohamed S. Elfeky ◽

Mohamed E. Serag

Keyword(s):

Elevated Temperature ◽

Bond Strength ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Mechanical Tests ◽

Nano Silica ◽

Content Type ◽

Post Exposure ◽

Concrete Mix ◽

Bond Strengths

Purpose This paper aims to inspect the effect of indirect elevated temperature on the mechanical performance of nano silica concrete (NSC). The effect on both compressive and bond strengths is studied. Pre- and post-exposure to elevated temperature ranges of 200 to 600°C is examined. A range covered by three percentages of 1.5, 3 and 4.5 per cent nano silica (NS) in concrete mixes is tested. Design/methodology/approach Pre-exposure mechanical tests (normal conditions – room temperature), using 3 per cent NS in the concrete mix, led to the highest increase in both compressive and bond strengths (43 per cent and 38.5 per cent, respectively), compared to the control mix without NS (based on 28-day results). It is worth noticing that adding NS to the concrete mixes does not have a significant effect on improving early-age strength. Besides, permeability tests are performed on NSC with different NS ratios. NS improved the concrete permeability for all tested percentages of NS. The maximum reduction is accompanied by the maximum percentage used (4.5 per cent NS in the NSC mix), reducing permeability to half the value of the concrete mix without NS. As for post-exposure to elevated-temperature mechanical tests, NSC with 1.5 per cent NS exhibited the lowest loss in strength owing to indirect heat exposure of 600°C; the residual compressive and bond strengths are 73 per cent and 35 per cent, respectively. Findings The dispersion technique of NS has a key role in NSC-distinguished mechanical performance with NSC having lower NS percentages. NS significantly improved bond strength. NS has a remarkable effect on elevated temperature endurance. The bond strength of NSC exposed to elevated temperatures suffered faster deterioration than compressive strength of the exposed NSC. Research limitations/implications A special scale factor needs to be investigated for the NSC. Originality/value Although a lot of effort is placed in evaluating the benefits of using nano materials in structural concrete, this paper presents one of the first outcomes of the thermal effects on concrete mixes with NS as a partial cement replacement.

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Mechanical Performance of Natural Fibers Reinforced Geopolymer Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.758.139 ◽

2013 ◽

Vol 758 ◽

pp. 139-145 ◽

Cited By ~ 11

Author(s):

Edvaldo Amaro S. Correia ◽

Sandro Marden Torres ◽

Marcio Eliel de Oliveira Alexandre ◽

Kelly C. Gomes ◽

Normando P. Barbosa ◽

...

Keyword(s):

Mechanical Properties ◽

Composite Materials ◽

Mechanical Performance ◽

Natural Fibers ◽

Mechanical Tests ◽

Ananas Comosus ◽

Classical Type ◽

Pineapple Leaf Fiber ◽

Agave Sisalana ◽

Geopolymer Composites

The use of geopolymers as matrix in composites with syntactical fibers have been studied and proposed in the literature. Nonetheless, for the best know of the authors, there are no researches about the use of geopolymers as matrix in composites with natural fibers. The use of natural fibers is increasing in the automotive industries. One of the problems to expand the use of natural fibers in composite materials is the low fire resistance of the classical type of polymers. In this sense, geopolymeric matrices open up horizons for this type of application. This paper studies composites with geopolymeric matrices reinforced with two types of natural fibers: sisal (Agave Sisalana) and pineapple leaf fiber (PALF-Ananas Comosus). The mechanical properties of these new composites are investigated by mechanical tests. The results confirm the increasing in the mechanical performance whenever the fibers are under traction stress.

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Assessment of hardening due to non-coherent precipitates in tungsten-rhenium alloys at the atomic scale

Scientific Reports ◽

10.1038/s41598-019-52521-x ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

G. Bonny ◽

A. Bakaev ◽

D. Terentyev

Keyword(s):

Large Scale ◽

Precipitation Hardening ◽

Elevated Temperatures ◽

Mechanical Tests ◽

Nuclear Industry ◽

Atomic Scale ◽

Atomistic Simulations ◽

Fusion Applications ◽

Precipitate Shape ◽

The Impact

Abstract In metallurgical applications, precipitation strengthening is of great technological importance to engineer materials with the required strength. While precipitation hardening is essential for many applications involving operation at elevated temperatures, its subsequent embrittlement can be a showstopper for the overall performance of a component. In the nuclear industry, irradiation-induced/enhanced precipitation and the resulting embrittlement often limit the lifetime of components. In fusion applications, tungsten (W) based alloys are known to harden and embrittle as a result of irradiation-assisted transmutation to rhenium (Re) and its subsequent precipitation into non-coherent precipitates. Hence, a fundamental understanding of the interaction of dislocations with non-coherent precipitates is of great interest. In the present work, the interaction of dislocations with non-coherent Re-rich σ, χ and hcp phase precipitates embedded in a bcc W matrix is assessed. Large-scale atomistic simulations are performed to clarify the interaction mechanisms and derive the obstacle strength of the precipitates in the quasi-static limit. Thereby the impact of precipitate shape, size, interspacing and composition is assessed. Based on those results, an analytical model to predict precipitation hardening of σ, χ and hcp phase particles in bcc W is proposed and compared to available experimental data from mechanical tests on irradiated materials.

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