scholarly journals COMPRESSIVE PROPERTIES OF AUXETIC STRUCTURES WITH CONTROLLED STIFFNESS OF STRUT JOINTS

2019 ◽  
Vol 25 ◽  
pp. 17-20
Author(s):  
Tomáš Doktor ◽  
Tomáš Fíla ◽  
Petr Koudelka ◽  
Daniel Kytýř ◽  
Ondřej Jiroušek
Keyword(s):  
Experimental Study ◽  
3D Printing ◽  
Cross Section ◽  
Base Material ◽  
Compressive Properties ◽  
Entire Cross Section ◽  
Static Compression ◽  
Auxetic Structures ◽  
Collapse Failure ◽  
Quasi Static Compression

Presented paper deals with experimental study on compressive properties of auxetics with controlled stiffness of strut joints. The variable strut joints properties were simulated by adding extra amount of material in the struts’ intersection regions. Four groups of inverted honeycomb structures were prepared by multi-jet 3D printing and tested in quasi-static compression. The structure collapsed gradually, however after the first collapse, failure in entire cross-section occurred due to the brittle nature of the base material. The behavior up to the first collapse was consistent among the specimens within each group, while differed slightly subsequently. With higher reinforcement in the joints, results showed increasing stress at the first collapse (ultimate compressive stress) while the strain at the first collapse remained unchanged. The auxetic behaviour became less significant with increasing joints’ reinforcement.

Experimental and theoretical study of sandwich composites with Z-pins under quasi-static compression loading

2021 ◽  
pp. 136943322110073
Author(s):  
Erdem Selver ◽  
Gaye Kaya ◽  
Hussein Dalfi
Keyword(s):  
Vinyl Ester ◽  
Failure Modes ◽  
Critical Role ◽  
Sandwich Composites ◽  
Test Results ◽  
Compressive Properties ◽  
Element Analysis ◽  
Static Compression ◽  
Quasi Static Compression ◽  
Good Agreement

This study aims to enhance the compressive properties of sandwich composites containing extruded polystyrene (XPS) foam core and glass or carbon face materials by using carbon/vinyl ester and glass/vinyl ester composite Z-pins. The composite pins were inserted into foam cores at two different densities (15 and 30 mm). Compression test results showed that compressive strength, modulus and loads of the sandwich composites significantly increased after using composite Z-pins. Sandwich composites with 15 mm pin densities exhibited higher compressive properties than that of 30 mm pin densities. The pin type played a critical role whilst carbon pin reinforced sandwich composites had higher compressive properties compared to glass pin reinforced sandwich composites. Finite element analysis (FE) using Abaqus software has been established in this study to verify the experimental results. Experimental and numerical results based on the capabilities of the sandwich composites to capture the mechanical behaviour and the damage failure modes were conducted and showed a good agreement between them.

scholarly journals Compressive Properties and Failure Mechanisms of Gradient Aluminum Foams Prepared by a Powder Metallurgy Method

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1337
Author(s):  
Wenzhan Huang ◽  
Guangming Liu ◽  
Huaying Li ◽  
Fang Wang ◽  
Yanli Wang
Keyword(s):  
Aluminum Foam ◽  
Sodium Thiosulfate ◽  
Powder Metallurgy Method ◽  
Deformation Characteristics ◽  
Compressive Properties ◽  
Aluminum Foams ◽  
Static Compression ◽  
Powder Sintering ◽  
Powder Particles ◽  
Quasi Static Compression

A layered gradient aluminum foam was prepared by powder sintering with sodium thiosulfate (Na2S2O3) particles as the cell-forming agent. By cutting, polishing and observing under a microscope, it was found that the aluminum powder particles were not completely melted after sintering but were only combined by surface melting. Based on the quasi-static compression test and the macroscopic diagram of the sample during deformation, the mechanical properties of gradient aluminum foam were studied, and their deformation characteristics and mechanism were analyzed and discussed.

scholarly journals Compressive properties of auxetic structures produced with direct 3D printing

2016 ◽  
Vol 50 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Petr Koudelka ◽  
Ondrej Jiroušek ◽  
Tomáš Fíla ◽  
Tomáš Doktor
Keyword(s):  
3D Printing ◽  
Compressive Properties ◽  
Auxetic Structures

Design of an auxetic cellular structure with different elastic properties in its three orthogonal directions

2021 ◽  
Vol 235 (6) ◽  
pp. 1341-1350
Author(s):  
Rodrigo Valle ◽  
Gonzalo Pincheira ◽  
Víctor Tuninetti
Keyword(s):  
Cellular Structure ◽  
Topological Analysis ◽  
Beam Theory ◽  
Fused Filament Fabrication ◽  
Topology Analysis ◽  
Static Compression ◽  
Auxetic Structures ◽  
Auxetic Structure ◽  
Quasi Static Compression ◽  
Good Agreement

Auxetic structures have become one of the most studied types of cellular structure in recent years, thanks to their highly specific mechanical properties. Most microstructures are designed with homogeneous properties in their main axes; however, in this research, we propose an innovative asymmetric 3D auxetic structure based on a 2D configuration of cells drawn from the literature. The new auxetic cell is designed by topology analysis using classical Timoshenko beam theory. To validate the design, samples were constructed by fused filament fabrication with ABSplus, and tested under quasi-static compression to determine Young's modulus in the three orthogonal directions. The experimental results show good agreement with the topological analysis and reveal that the proposed cell can transmit a different mechanical behavior to the macrostructure in its three orthogonal directions.

scholarly journals Deformation Process of 3D Printed Structures Made from Flexible Material with Different Values of Relative Density

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2120 ◽  
Author(s):  
Paweł Płatek ◽  
Kamil Rajkowski ◽  
Kamil Cieplak ◽  
Marcin Sarzyński ◽  
Jerzy Małachowski ◽  
...  
Keyword(s):  
3D Printing ◽  
Relative Density ◽  
Computer Simulations ◽  
Deformation Process ◽  
Thermoplastic Polyurethane ◽  
Base Material ◽  
Compression Tests ◽  
Static Compression ◽  
Flexible Material ◽  
3D Printed

The main aim of this article is the analysis of the deformation process of regular cell structures under quasi-static load conditions. The methodology used in the presented investigations included a manufacturability study, strength tests of the base material as well as experimental and numerical compression tests of developed regular cellular structures. A regular honeycomb and four variants with gradually changing topologies of different relative density values have been successfully designed and produced in the TPU-Polyflex flexible thermoplastic polyurethane material using the Fused Filament Fabrication (FFF) 3D printing technique. Based on the results of performed technological studies, the most productive and accurate 3D printing parameters for the thermoplastic polyurethane filament were defined. It has been found that the 3D printed Polyflex material is characterised by a very high flexibility (elongation up to 380%) and a non-linear stress-strain relationship. A detailed analysis of the compression process of the structure specimens revealed that buckling and bending were the main mechanisms responsible for the deformation of developed structures. The Finite Element (FE) method and Ls Dyna software were used to conduct computer simulations reflecting the mechanical response of the structural specimens subjected to a quasi-static compression load. The hyperelastic properties of the TPU material were described with the Simplified Rubber Material (SRM) constitutive model. The proposed FE models, as well as assumed initial boundary conditions, were successfully validated. The results obtained from computer simulations agreed well with the data from the experimental compression tests. A linear relationship was found between the relative density and the maximum strain energy value.

Experimental Study on Cross Section Lateral Compression Energy Absorption Characteristics of Three Types of Steel Tubes

2014 ◽  
Vol 624 ◽  
pp. 228-235
Author(s):  
Zhao Peng Zhou ◽  
Qin Fang ◽  
Fei Li ◽  
Xin Hua Zhu ◽  
Yan Mi Wang
Keyword(s):  
Experimental Study ◽  
Energy Absorption ◽  
Cross Section ◽  
Engineering Application ◽  
High Energy ◽  
Steel Tube ◽  
Steel Tubes ◽  
Static Compression ◽  
Square Steel Tube ◽  
Absorption Characteristics

In order to understand the energy absorption characteristics of various types of steel tubes and provide certain basis for model selection in the engineering application, this paper adopts the experimental study to conduct the comparative study on lateral quasi-static compression energy absorption characteristics of three types of steel tubes, i.e. round steel tube, square steel tube and hexagonal steel tube. Through analysis of the test phenomenon, the total energy absorbed by equal deformation and the energy absorbed per unit mass, the result shows that the steel tube with hexagonal cross section is provided with such advantages as steady absorption, stable deformation mode and high energy absorption ratio, and is more suitable for application in engineering than the round steel tube and the square steel tube.

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