scholarly journals Experimental Study on Improving the Mechanical Properties of Material Extrusion Rapid Prototyping Polylactic Acid Parts by Applied Vibration

2021 ◽  
Vol 11 (4) ◽  
pp. 1820
Author(s):  
Shijie Jiang ◽  
Tiankuo Dong ◽  
Yang Zhan ◽  
Weibing Dai ◽  
Ming Zhan
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Rapid Prototyping ◽  
Experimental Tests ◽  
Point Of View ◽  
Material Extrusion ◽  
Strength And Plasticity ◽  
First Time ◽  
Process Material ◽  
Orthogonal Anisotropy

Due to the stratified nature of the manufacturing process, material extrusion (ME) parts have lower mechanical properties than those fabricated by traditional technology. This is one of the most significant defects hindering the development and application of this rapid prototyping technique. In this paper, vibration was applied to the ME process by using piezoelectric ceramics for the first time to improve the mechanical properties of the built parts. The vibrating ME equipment was established, and the specimens processed in different build directions were individually fabricated without applied vibration and with different applied vibrations. To quantify the effect of applied vibration on their mechanical properties and to summarize the influencing rule, a series of experimental tests were then performed on these specimens. A comparison between the testing results shows that the tensile strength and plasticity of the specimens, especially those processed in the Z direction, can be obviously improved by applied vibration. The orthogonal anisotropy is decreased obviously. The improvement becomes greater with increasing vibration frequency or amplitude. From the microscopic point of view, it can be seen that applied vibration can reduce the part’s defects of porosity and inclusion as well as separation between layers and, thereby, improve the bonding strength.

Numerical Simulation of Laser Forming of Aluminum Sponges: Effect of Temperature and Heat Treatments

2014 ◽  
Vol 611-612 ◽  
pp. 731-738 ◽  
Author(s):  
Fabrizio Quadrini ◽  
Denise Bellisario ◽  
Daniele Ferrari ◽  
Loredana Santo ◽  
Anna Santarsiero
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Experimental Tests ◽  
Point Of View ◽  
Material Behavior ◽  
Effect Of Temperature ◽  
Laser Forming ◽  
Laser Exposure ◽  
Fe Model ◽  
Aluminum Foams

Laser forming ofopen-cell aluminum foams can be modeled by means of 3D thermo-mechanical models but the correct evaluation of the alloy material properties is a key-factor for obtaining good predictions. In order to increase the model predictability from a quantitative point of view, further information about the material behavior under laser exposure is necessary. In this study the effect of the temperature on the mechanical properties of a commercial aluminum sponge has been evaluated in terms of yielding stress and tangent modulus. Experimental tests have been performed by compression and used to infer mechanical properties by means of a 3D FE model. The same approach has been used also to evaluate the effect of a heat treatment of the sponge on the material behavior during forming. In conclusion numerical simulation of laser heating has been used to show the effect of the laser-material interaction on the final homogeneity of processed foams.

CORROSION – BUCKLING INTERACTION OF 6061-T4 AL ALLOY FIXED – PINNED COLUMNS – EXPERIMENTAL STUDY

2018 ◽  
Vol 18 (1) ◽  
pp. 154-166
Author(s):  
Husain J Al-alkawi ◽  
Abduljabbar O Hanfesh ◽  
Hussein F Ajaj
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Pitting Corrosion ◽  
Experimental Analysis ◽  
Factor Of Safety ◽  
Experimental Tests ◽  
Al Alloy ◽  
Soil Corrosion ◽  
Maximum Reduction ◽  
Corrosion Time

Compression buckling experimental tests was carried out for long and intermediatecolumns made of 6061-T4 AL- alloy. Two different soil corrosion time were adopted i.e.30days and 60 days using 27 samples. The experimental analysis revealed that increasing thecorrosion time negatively affects the mechanical properties of metals such as the specimensof 60 days corroded have 1.68% reduction in ultimate strength, also increasing the corrosiontime reduces the critical load such as the maximum reduction was 4.24% in critical bucklingload for 60 days corrosion time. Perry-Robertson theory was applied to the experimentaldata and it was found that the above theory can satisfactory predicted the critical bucklingload (Pcr) with a factor of safety equal to 1.2. The ratio of corroded Pcr to dry Pcr wasalways less than unity. This indication explains the effect of pitting corrosion on bucklingbehavior of 6061-T4 AL- alloy

Experimental study of the functional and mechanical properties of shape memory polymer composites for a reflector of the space antenna

2020 ◽  
Vol 86 (1) ◽  
pp. 51-56
Author(s):  
Egor V. Moskvichev ◽  
Alexey Yu. Larichkin
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Shape Memory ◽  
Polymer Composite ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Experimental Tests ◽  
Polymer Composite Material ◽  
Operating Conditions ◽  
Space Antenna

Experimental study of the shape memory polymer composite is carried out as a part of scientific and technological work aimed at development of the new promising reflectors for space antenna. The studied material consists of three-layered carbon biaxial fabric St 12073 impregnated with a polyurethane-based Diaplex MP5510 polymer matrix. This material is intended for manufacturing a frame used in the construction of a precise composite reflector of space antenna. When opening the reflector to the transport position, the rim activated by heating recovers a previously specified shape thus increasing the rigidity of the reflector at the periphery and enhancing the accuracy of the reflecting surface. To study the functional and mechanical properties of the rim material in manufacturing and operating conditions, experimental tests were carried out on the samples with different schemes of reinforcement: [03], [0/±60] and [0/±45]. The main goal of the study is to determine the degree and rate of the shape recovery, reinforcement angles, deformation rate and exposure time in the strained state. The developed test program included several stages. At the first stages, tests were carried out for fixing and restoring the shape upon three-point bending of flat samples at a strain rate of 1, 5, and 10 mm/sec and exposure of the specimens in deformed state for 24, 48, and 96 h. According to the results the material with the reinforcement angles [03] was accepted as optimal for the rim design, as it has maximal shape recovery parameters. For the selected material at the final stage of the study, the elastic modulus and tensile strength were determined at operating temperatures –50, +20, and +60°C. The tests showed that the studied polymer composite material has the desired shape memory properties and is promising for the rim manufacturing provided the heat insulation during operation.

scholarly journals Characterization of Newly Developed Zinc Composite with the Content of 8 wt.% of Hydroxyapatite Particles Processed by Extrusion

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1716 ◽  
Author(s):  
Jan Pinc ◽  
Jaroslav Čapek ◽  
Vojtěch Hybášek ◽  
Filip Průša ◽  
Klára Hosová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Orthopedic Implants ◽  
Extrusion Process ◽  
Point Of View ◽  
Material Structure ◽  
Compressive Yield Strength ◽  
Corrosion Properties ◽  
New Processing ◽  
First Time

Zinc and its alloys belong to a group of biodegradable materials, which can be potentially used for the preparation of temporary orthopedic implants. The research of biodegradable zinc materials revealed a lot of limitations; however, the new processing approaches of those materials can enhance their properties, which are insufficient for now. In this study, the zinc composite with 8 wt.% of hydroxyapatite (Zn/HA8) prepared for the first time by extrusion process was characterized from the point of view of the structural, mechanical and corrosion properties. The extrusion process led to good integrity of the interfaces between the zinc and hydroxyapatite particles. Mechanical behavior confirmed the role of hydroxyapatite as a defect in the material structure, which led to a decrease of the Zn/HA8 mechanical properties by approximately 30% (compressive yield strength (CYS) = 154 MPa Zn, 113 MPa Zn/HA8). Despite that, the Zn/HA8 composite showed sufficient mechanical properties for cancellous bone replacement and reached the lower limit for cortical bone. Additionally, the presence of hydroxyapatite caused the preferential precipitation of hydroxyapatite (HA) from the solution and can lead to a significant enhancement of the tissue/implant interface interactions.

A Study on Polymer Particle Flow in a Disk Zone of a Screw-Disk Extruder

2014 ◽  
Vol 35 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Tomasz Rydzkowski ◽  
Iwona Michalska-Pożoga
Keyword(s):  
Mechanical Properties ◽  
Computer Simulations ◽  
Particle Motion ◽  
Polymer Melt ◽  
Experimental Tests ◽  
Polymer Particle ◽  
Particle Flow ◽  
Material Particle ◽  
Motion Trajectories ◽  
Stretching Effect

Abstract The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.

Thanato-Laboratorien. Theorien von Tod und Sterben und Elias Canettis Buch gegen den Tod

2020 ◽  
Vol 4 (1) ◽  
pp. 67-86
Author(s):  
Elisabeth Heyne
Keyword(s):  
Human Life ◽  
Death And Dying ◽  
Point Of View ◽  
Visual Images ◽  
Elias Canetti ◽  
History Of ◽  
Series Of Experiments ◽  
First Time ◽  
Textual Form ◽  
Or History

AbstractAlthough visual culture of the 21th century increasingly focuses on representation of death and dying, contemporary discourses still lack a language of death adequate to the event shown by pictures and visual images from an outside point of view. Following this observation, this article suggests a re-reading of 20th century author Elias Canetti. His lifelong notes have been edited and published posthumously for the first time in 2014. Thanks to this edition Canetti's short texts and aphorisms can be focused as a textual laboratory in which he tries to model a language of death on experimental practices of natural sciences. The miniature series of experiments address the problem of death, not representable in discourses of cultural studies, system theory or history of knowledge, and in doing so, Canetti creates liminal texts at the margins of western concepts of (human) life, science and established textual form.

A Nabatean port on the Red Sea: note on the pottery finds from al-Qusayr (al-Wajh, Saudi Arabia)

2020 ◽  
Author(s):  
Caroline Durand
Keyword(s):  
Saudi Arabia ◽  
19Th Century ◽  
Red Sea ◽  
Point Of View ◽  
The Other ◽  
Trade Routes ◽  
Other Hand ◽  
Roman Egypt ◽  
Pottery Sherds ◽  
First Time

Al-Qusayr is located 40 km south of modern al-Wajh, roughly 7 km from the eastern Red Sea shore. This site is known since the mid-19th century, when the explorer R. Burton described it for the first time, in particular the remains of a monumental building so-called al-Qasr. In March 2016, a new survey of the site was undertaken by the al-‘Ula–al-Wajh Survey Project. This survey focused not only on al-Qasr but also on the surrounding site corresponding to the ancient settlement. A surface collection of pottery sherds revealed a striking combination of Mediterranean and Egyptian imports on one hand, and of Nabataean productions on the other hand. This material is particularly homogeneous on the chronological point of view, suggesting a rather limited occupation period for the site. Attesting contacts between Mediterranean merchants, Roman Egypt and the Nabataean kingdom, these new data allow a complete reassessment of the importance of this locality in the Red Sea trade routes during antiquity.

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