scholarly journals The Influence of Polypropylene Fiber on the Working Performance and Mechanical Anisotropy of 3D Printing Concrete

2021 ◽  
Vol 19 (12) ◽  
pp. 1264-1274
Author(s):  
Yu Zhao ◽  
Xikai Wu ◽  
Lingli Zhu ◽  
Zhang Yang ◽  
Youkai Wang ◽  
...  
Keyword(s):  
3D Printing ◽  
Polypropylene Fiber ◽  
Mechanical Anisotropy ◽  
Working Performance

scholarly journals Overview of the use of 3D printing in forensic medicine

Rechtsmedizin ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 292-299
Author(s):  
W. Schweitzer ◽  
M. Thali ◽  
E. Aldomar ◽  
L. Ebert
Keyword(s):  
Thermal Properties ◽  
3D Printing ◽  
Rapid Prototyping ◽  
Forensic Medicine ◽  
Low Cost ◽  
Spare Parts ◽  
Mechanical Anisotropy ◽  
Development Phase ◽  
Biomechanical Models ◽  
End Products

Abstract In forensic medicine the use of so-called 3D printing is a niche application, whereas developments elsewhere in this field are rapidly advancing worldwide. The most common and widespread technology is fusion deposit modelling with polylactic acids (PLA). Although the equipment and materials may be relatively inexpensive and 3D printing relatively fast, the resulting end products tend to also have negative properties, such as poor durability and mechanical anisotropy, which may be an issue depending on the application. In forensic medicine, applications in the field of weapons technology and biomechanical models are realistic and 3D printing is already being used for demonstrations at court hearings and in teaching and also as a technique for building spare parts or accessories. Having a low-cost option for rapid prototyping on-site is particularly useful for the development phase. For finished 3D designs more expensive manufacturing options with a choice of materials with significantly broader mechanical or thermal properties are available. As the technology is undergoing major changes, one should carefully consider whether to enter the field oneself, buy own hardware, use a 3D printing service or seek cooperation possibly with a nearby partner.

scholarly journals Study of a New 5-DOF Parallel Mechanism for Multi-Directional 3D Printing

2020 ◽  
Author(s):  
Yesong Wang ◽  
Changhuai Lyu ◽  
Jiang Liu ◽  
Jinguang Zhang ◽  
Zhixin Jia
Keyword(s):  
3D Printing ◽  
Parallel Mechanism ◽  
Closed Loop ◽  
Three Dimensional ◽  
Line Geometry ◽  
Vector Method ◽  
Grassmann Line Geometry ◽  
Working Performance ◽  
Geometry Method ◽  
Unstable Problem

Abstract This paper first designs a new 5-DOF parallel mechanism with 5PUS-UPU for multi-directional 3D printing, and then analyses its DOF by traditional Grubler-Kutzbach and motion spiral theory. It theoretically shows that the mechanism meets the requirement of 5 dimensions of freedoms including three-dimensional movement and two-dimensional rotation. Basing on this, the real mechanism is built, but unfortunately it is found unstable in some positions. Grassmann line geometry method is applied to analyze its unstable problem caused by singular posture, and then an improving method is put forward to solve it. With the improved mechanism, closed loop vector method is employed to establish the inverse position equation of the parallel mechanism, and kinematics analysis is carried out to get the mapping relationships between position, speed and acceleration of moving and fixed platform, Monte Carlo method is used to analyze the workspace of the mechanism, to explore the influencing factors of workspace, and then to get the better workspace. Finally an experiment is designed to verify the mechanism working performance to satisfy the spatial motion requirements of multi-directional 3D printing.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

Michael Pawlyn: Push the limits of 3D printing

Nature ◽  
2013 ◽  
Vol 494 (7436) ◽  
pp. 174-174 ◽  
Author(s):  
Michael Pawlyn
Keyword(s):  
3D Printing

High-resolution 3D printing in seconds

Nature ◽  
2020 ◽  
Vol 588 (7839) ◽  
pp. 594-595
Author(s):  
Cameron Darkes-Burkey ◽  
Robert F. Shepherd
Keyword(s):  
High Resolution ◽  
3D Printing
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