scholarly journals Analysis of the behaviour of 3D samples printed by FFF/FDM technologies under bending stress with a focus on infill

2021 ◽  
Vol 1209 (1) ◽  
pp. 012041
Author(s):  
D Juračka ◽  
M Kawulok
Keyword(s):  
Load Capacity ◽  
Variable Density ◽  
Bending Stress ◽  
Continuous Fiber ◽  
Thermoplastic Material ◽  
Bending Tests ◽  
3D Printed ◽  
Printing Time

Abstract The focus of this paper is to explore the possibilities of optimizing 3D printed elements produced by FFF/FDM technology based on bending tests according to ČSN EN ISO 178 (64 0607) with variations in the settings of the printing itself. The principle of FFF/FDM is the printing of a continuous fiber made of thermoplastic material, which is applied by machine to the previously printed fiber. There are many combinations of possible print settings, and one of them is the geometry of the inner density with variable density. Their resulting maximum values of the achieved load were then compared with the weight (amount of material used) and printing time. The result is a comparison to achieve economical printing with the greatest possible load capacity.

Bending fracture rule for 3D-printed curved continuous-fiber composite

2018 ◽  
Vol 28 (4) ◽  
pp. 383-395 ◽  
Author(s):  
Kouki Ishii ◽  
Akira Todoroki ◽  
Yoshihiro Mizutani ◽  
Yoshiro Suzuki ◽  
Yoichiro Koga ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Continuous Fiber ◽  
3D Printed ◽  
Bending Fracture

scholarly journals Advanced Industrial Turbine Gear Calculation Methods

1978 ◽  
Author(s):  
Manfred Hirt
Keyword(s):  
Vibration Analysis ◽  
Load Capacity ◽  
Bending Stress ◽  
Calculation Methods ◽  
Tooth Width

Calculation of industrial turbine gears is more than calculation of load capacity concerning Hertzian pressure, bending stress, and scoring phenomena. It also includes, for example, a complete vibration analysis of the gear, shaft, and bearing systems. Some newer methods used in the German practice for these calculations and also for determining exact tooth width corrections and some aspects of the new ISO calculation methods are discussed.

A Novel Variable Stiffness Compliant Robotic Gripper Based on Layer Jamming

2019 ◽  
Author(s):  
Yuan Gao ◽  
Xiguang Huang ◽  
Ishan Singh Mann ◽  
Hai-Jun Su
Keyword(s):  
Load Capacity ◽  
Variable Stiffness ◽  
Fold Increase ◽  
Structural Stiffness ◽  
Working Process ◽  
Shape Morphing ◽  
Individual Finger ◽  
Low Load ◽  
3D Printed ◽  
Stiffness Variation

Abstract In this paper, we present a novel compliant robotic gripper with three variable stiffness fingers. While the shape morphing of the grippers is cable-driven, the stiffness variation is enabled by layer jamming. The inherent flexibility makes compliant grippers suitable for tasks such as grasping soft and irregular objects. However, their relatively low load capacity due to low structural stiffness limits their applications. Variable stiffness robotic grippers have the potential to address this challenge as their stiffness can be tuned on demand based on the needs of tasks. Layer jamming is an emerging method for variable stiffness due to its advantages of light weight, simple and quick actuation. In our design, the compliant backbone of the fingers is made of 3d printed PLA material. Four thin film materials are attached to each side of the skeleton. The working process of the robotic gripper follows two basic steps. First, the compliant skeleton is bent to a desired shape by actuating a tension cable via a servo motor. Second, upon application of a negative pressure by a vacuum pump, the finger is stiffened up owing to the increasing of the friction between contact surfaces of layers preventing their relative movement. Since the structural stiffness of the fingers is increased, their load capacity will be increased proportionally. When the air pressure is sufficiently large, the morphed shape can even be locked (no slipping). Test for stiffness of individual finger and load capacity of the robotic gripper are conducted to validate capability of the design. The results showed a 69-fold increase in stiffness of individual finger and a 30-fold increase in gripper’s load capacity.

GRP pipe bends subjected to out-of-plane flexure with and without pressure

1988 ◽  
Vol 23 (4) ◽  
pp. 187-199 ◽  
Author(s):  
R Kitching ◽  
P Myler ◽  
A L Tan
Keyword(s):  
Constant Pressure ◽  
Design Procedure ◽  
Bending Stress ◽  
Bend Radius ◽  
Pipe Bend ◽  
Bending Tests ◽  
Out Of Plane ◽  
Chopped Strand Mat ◽  
Plane Flexure ◽  
Typical Design

Out-of-plane bending tests were carried out on eight E-glass reinforced polytester resin, 90 degree pipe bends of 250 mm diameter and 250 mm bend radius. Each bend specimen tested had 1175 mm long tangent pipes attached, and construction was by hand lay-up, the glass being in the form of chopped strand mat (either 2.4 kg/m2 or 3.6 kg/m2). In all cases low loads were applied so that deformations were sensibly linear. Strains and displacements were measured and distributions were compared with estimates calculated from pipe bend theory for isotropic materials under plane stress, but modified for composites by using separate moduli for direct and bending stress conditions. Further measurements were taken for internal pressure (only) loadings on five of the specimens, and finally for out-of-plane flexure loading combined with constant pressure. Again measured values were compared with theory. Results are discussed in relation to a typical design procedure for such pipe components.

Comparisons of Bending Stiffness of 3D Printed Samples of Different Materials

2016 ◽  
Author(s):  
Mahbub Ahmed ◽  
Md. R. Islam ◽  
Justin Vanhoose ◽  
Lionel Hewavitharana ◽  
Aaron Stanich ◽  
...  
Keyword(s):  
Bending Stiffness ◽  
Bending Test ◽  
Testing System ◽  
Materials Testing ◽  
Flexural Stiffness ◽  
Result Section ◽  
Bending Tests ◽  
System A ◽  
3D Printers ◽  
3D Printed

3D printing technology has become more affordable than ever before. Today 3D printers are not only used for making prototypes but are also being used to make good quality 3D parts for different purposes. A wide variety of filament materials are used in the market. Finding bending stiffness of different plastic filaments is the particular interest in the current study. The purpose of the project is to investigate the bending stiffness of different 3D printed beam samples. A series of samples for performing bending tests were designed using a solid modeling tool. These samples were printed with four different plastic filaments on a 3D printer in the engineering Lab of Southern Arkansas University. The samples were tested for flexural stiffness (bending) using a materials testing system. A popular 3-point bending test was conducted for this purpose. The force vs. deflection data was obtained to obtain the flexural stiffness of the beam samples. The results were discussed in detail in the result section of this paper.

scholarly journals Manufacturing a First Upper Molar Dental Forceps Using Continuous Fiber Reinforcement (CFR) Additive Manufacturing Technology with Carbon-Reinforced Polyamide

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2647
Author(s):  
Roland Told ◽  
Gyula Marada ◽  
Szilard Rendeki ◽  
Attila Pentek ◽  
Balint Nagy ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Medical Devices ◽  
Fiber Reinforcement ◽  
Strong Impact ◽  
Vertical Force ◽  
Continuous Fiber ◽  
Fused Filament Fabrication ◽  
Sem Images ◽  
3D Printed ◽  
Upper Molar

3D printing is an emerging and disruptive technology, supporting the field of medicine over the past decades. In the recent years, the use of additive manufacturing (AM) has had a strong impact on everyday dental applications. Despite remarkable previous results from interdisciplinary research teams, there is no evidence or recommendation about the proper fabrication of handheld medical devices using desktop 3D printers. The aim of this study was to critically examine and compare the mechanical behavior of materials printed with FFF (fused filament fabrication) and CFR (continuous fiber reinforcement) additive manufacturing technologies, and to create and evaluate a massive and practically usable right upper molar forceps. Flexural and torsion fatigue tests, as well as Shore D measurements, were performed. The tensile strength was also measured in the case of the composite material. The flexural tests revealed the measured force values to have a linear correlation with the bending between the 10 mm (17.06 N at 5000th cycle) and 30 mm (37.99 N at 5000th cycle) deflection range. The findings were supported by scanning electron microscopy (SEM) images. Based on the results of the mechanical and structural tests, a dental forceps was designed, 3D printed using CFR technology, and validated by five dentists using a Likert scale. In addition, the vertical force of extraction was measured using a unique molar tooth model, where the reference test was carried out using a standard metal right upper molar forceps. Surprisingly, the tests revealed there to be no significant differences between the standard (84.80 N ± 16.96 N) and 3D-printed devices (70.30 N ± 4.41 N) in terms of extraction force in the tested range. The results also highlighted that desktop CFR technology is potentially suitable for the production of handheld medical devices that have to withstand high forces and perform load-bearing functions.

scholarly journals Comparison between Tests and Simulations Regarding Bending Resistance of 3D Printed PLA Structures

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4371
Author(s):  
Dorin-Ioan Catana ◽  
Mihai-Alin Pop ◽  
Denisa-Iulia Brus
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Process Parameters ◽  
Bending Stress ◽  
Test Results ◽  
Printing Process ◽  
Simulation Process ◽  
Bending Resistance ◽  
3D Printed

Additive manufacturing is one of the technologies that is beginning to be used in new fields of parts production, but it is also a technology that is constantly evolving, due to the advances made by researchers and printing equipment. The paper presents how, by using the simulation process, the geometry of the 3D printed structures from PLA and PLA-Glass was optimized at the bending stress. The optimization aimed to reduce the consumption of filament (material) simultaneously with an increase in the bending resistance. In addition, this paper demonstrates that the simulation process can only be applied with good results to 3D printed structures when their mechanical properties are known. The inconsistency of printing process parameters makes the 3D printed structures not homogeneous and, consequently, the occurrence of errors between the test results and those of simulations become natural and acceptable. The mechanical properties depend on the values of the printing process parameters and the printing equipment because, in the case of 3D printing, it is necessary for each combination of parameters to determine their mechanical properties through specific tests.

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