scholarly journals Mechanical Properties of Flexible TPU-Based 3D Printed Lattice Structures: Role of Lattice Cut Direction and Architecture

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2986
Author(s):  
Victor Beloshenko ◽  
Yan Beygelzimer ◽  
Vyacheslav Chishko ◽  
Bogdan Savchenko ◽  
Nadiya Sova ◽  
...  

This study addresses the mechanical behavior of lattice materials based on flexible thermoplastic polyurethane (TPU) with honeycomb and gyroid architecture fabricated by 3D printing. Tensile, compression, and three-point bending tests were chosen as mechanical testing methods. The honeycomb architecture was found to provide higher values of rigidity (by 30%), strength (by 25%), plasticity (by 18%), and energy absorption (by 42%) of the flexible TPU lattice compared to the gyroid architecture. The strain recovery is better in the case of gyroid architecture (residual strain of 46% vs. 31%). TPUs with honeycomb architecture are characterized by anisotropy of mechanical properties in tensile and three-point bending tests. The obtained results are explained by the peculiarities of the lattice structure at meso- and macroscopic level and by the role of the pore space.

2020 ◽  
Vol 90 (21-22) ◽  
pp. 2399-2410 ◽  
Author(s):  
Shahbaj Kabir ◽  
Hyelim Kim ◽  
Sunhee Lee

This study has investigated the physical properties of 3D-printable shape memory thermoplastic polyurethane (SMTPU) filament and its 3D-printed sinusoidal pattern obtained by fused deposition modeling (FDM) technology. To investigate 3D filaments, thermoplastic polyurethane (TPU) and SMTPU filament were examined by conducting infrared spectroscopy, x-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and a tensile test. Then, to examine the 3D-printed sinusoidal samples, a sinusoidal pattern was developed and 3D-printed. Those samples went through a three-step heating process: (a) untreated state; (b) 5 min heating at 70°C, cooling for 30 min at room temperature; and (c) a repeat of step 2. The results obtained by the three different heating processes of the 3D-printed sinusoidal samples were examined by XRD, DMTA, DSC and the tensile test to obtain the effect of heating or annealing on the structural and mechanical properties. The results show significant changes in structure, crystallinity and thermal and mechanical properties of SMTPU 3D-printed samples due to the heating steps. XRD showed the increase in crystallinity with heating. In DMTA, storage modulus, loss modulus and the tan σ peak position also changed for various heating steps. The DSC result showed that the Tg for different steps of the SMTPU 3D-printed sample remained almost the same at around 51°C. The tensile property of the TPU 3D-printed sinusoidal sample decreased in terms of both load and elongation with increased heating processes, while for the SMTPU 3D-printed sinusoidal sample, the load decreased but elongation increased about 2.5 times.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5720 ◽  
Author(s):  
Vicente Colomer-Romero ◽  
Dante Rogiest ◽  
Juan Antonio García-Manrique ◽  
Jose Enrique Crespo

Bio- and green composites are mainly used in non-structural automotive elements like interior panels and vehicle underpanels. Currently, the use of biocomposites as a worthy alternative to glass fibre-reinforced plastics (GFRPs) in structural applications still needs to be fully evaluated. In the current study, the development of a suited biocomposites started with a thorough review of the available raw materials, including both reinforcement fibres and matrix materials. Based on its specific properties, hemp appeared to be a very suitable fibre. A similar analysis was conducted for the commercially available biobased matrix materials. Greenpoxy 55 (with a biocontent of 55%) and Super Sap 100 (with a biocontent of 37%) were selected and compared with a standard epoxy resin. Tensile and three-point bending tests were conducted to characterise the hemp-based biocomposite.


Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3158 ◽  
Author(s):  
Santiago Cano ◽  
Tanja Lube ◽  
Philipp Huber ◽  
Alberto Gallego ◽  
Juan Alfonso Naranjo ◽  
...  

The fused filament fabrication (FFF) of ceramics enables the additive manufacturing of components with complex geometries for many applications like tooling or prototyping. Nevertheless, due to the many factors involved in the process, it is difficult to separate the effect of the different parameters on the final properties of the FFF parts, which hinders the expansion of the technology. In this paper, the effect of the fill pattern used during FFF on the defects and the mechanical properties of zirconia components is evaluated. The zirconia-filled filaments were produced from scratch, characterized by different methods and used in the FFF of bending bars with infill orientations of 0°, ±45° and 90° with respect to the longest dimension of the specimens. Three-point bending tests were conducted on the specimens with the side in contact with the build platform under tensile loads. Next, the defects were identified with cuts in different sections. During the shaping by FFF, pores appeared inside the extruded roads due to binder degradation and or moisture evaporation. The changes in the fill pattern resulted in different types of porosity and defects in the first layer, with the latter leading to earlier fracture of the components. Due to these variations, the specimens with the 0° infill orientation had the lowest porosity and the highest bending strength, followed by the specimens with ±45° infill orientation and finally by those with 90° infill orientation.


2017 ◽  
Vol 09 (02) ◽  
pp. 1750027 ◽  
Author(s):  
Fangfang Sun ◽  
Qing Zheng ◽  
Hualin Fan ◽  
Daining Fang

To construct a hierarchical lattice structure (HLS), truss wall is introduced into ordinary lattice structure (OLS). Young’s modulus, yield strength and buckling stress of HLSs were evaluated theoretically. Failure maps of different HLSs were plotted and compared based on the theoretical analyses. It is indicated that mechanical behaviors of hexagonal HLSs made of triangular lattice walls can be greatly enhanced by the hierarchical wall structure, while properties of triangular HLSs are weakened, except the anti-buckling resistance. When HLSs are made of bending-dominated honeycomb walls, their properties will be reduced, indicating that hierarchical structure should be appropriately designed to make ultra-light structures benefit from this construction. This viewpoint is strengthened by the discussions on the performances of high order lattice structures, where only bending-dominated HLSs with stretching-dominated lattice wall benefit from the hierarchy.


1999 ◽  
Vol 115 (4) ◽  
pp. 390-395 ◽  
Author(s):  
Hirokazu Nakano ◽  
Kazuro Satoh ◽  
Robert Norris ◽  
Tomoaki Jin ◽  
Tetsuya Kamegai ◽  
...  

Author(s):  
Haris Stamatopoulos ◽  
Francesco Mirko Massaro ◽  
Jalal Qazi

AbstractAt present, the mechanical properties of laterally loaded threaded fasteners with large diameters embedded in timber elements remain unknown. An experimental study of laterally loaded threaded rods with wood screw threads embedded perpendicular to grain in softwood elements (spruce and pine glulam and spruce LVL) is presented in this paper. Embedment tests with the load acting parallel and perpendicular to grain were carried out and the embedment strength and stiffness were quantified. For some test series, the experimental embedment strengths were lower compared to the predictions according to Eurocode 5 in terms of both mean and characteristic values. This finding indicates that the predictions by Eurocode 5 are not always conservative. To investigate the effect of the thread, additional series of embedment tests were carried out with smooth dowels featuring a diameter approximately equal to the core diameter of the threaded rods. Finally, the yielding moment of threaded rods was quantified based on a series of three-point bending tests of threaded rods. The experimentally determined yielding moment was significantly higher than the prediction of Eurocode 5.


2019 ◽  
Author(s):  
Lindsay Erndwein ◽  
Elahe Ganji ◽  
Ashley N. Hostetler ◽  
Adam Stager ◽  
Megan L. Killian ◽  
...  

ABSTRACTCrop plants are susceptible to yield loss by mechanical failure, which is called lodging. In maize (Zea mays), aerial nodal brace roots impart mechanical stability to plants, with previous studies showing that the lowest whorl of brace roots contributes the most. The features of brace roots that determine their contribution to mechanical stability are poorly defined. Here we tested the hypothesis that brace root mechanical properties vary between whorls, which may influence their contribution to mechanical stability. 3-point bending tests were used to determine that brace roots from the lowest whorl have the highest structural mechanical properties regardless of growth stage, and that these differences are largely due to brace root geometry within a genotype. Analysis of the brace root bending modulus determined that differences between genotypes are attributable to both geometry and material properties. These results support the role of brace root biomechanics to determine the brace root contribution to mechanical stability.HIGHLIGHTBrace root biomechanics vary within and between genotypes. These results support the importance of biomechanics to define the contribution of brace roots to mechanical stability.


2012 ◽  
Vol 567 ◽  
pp. 146-149 ◽  
Author(s):  
Xue Mei Fan ◽  
Jian Feng Wang ◽  
Cheng Jin Duan ◽  
Xiang Xin Xia ◽  
Zhao Hui Wang

In order to analyze the mechanical properties of Carbon/epoxy facings-Aluminum honeycomb sandwich structure, we simulated panels of different layers and core thickness using ABAQUS finite element analysis program. And three-point bending tests and shear tests were made on the same panels using electronic universal testing machine. In addition, we also made the same three-point bending tests on steel tubes to get a comparison with honeycomb sandwich panels. It could be seen that, the simulated results were basically identified with experimental results. The results indicated that core thickness played an important role in the panels’ bulking modulus, and number of carbon fiber layers decided the shear strength. As a whole, honeycomb sandwich structure was suitable for use in the car body with good mechanical properties under premise of lighter.


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