Self-Locking Origami Structures and Locking-Induced Piecewise Stiffness

2017 ◽  
Author(s):  
Hongbin Fang ◽  
Shih-Cheng A. Chu ◽  
K. W. Wang
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Design Guidelines ◽  
The Self ◽  
Structural Stiffness ◽  
Pattern Design ◽  
Stiffness Characteristics ◽  
Stiffness Profile ◽  
Multiple Cells ◽  
Sudden Jump

The folding motion of an origami structure can be stopped at a non-flat position when two of its facets bind together. Such facet-binding will induce self-locking so that the overall origami structure can stay at a pre-specified configuration without the help of additional locking devices or actuators. This research investigates the designs of self-locking origami structures and the locking-induced kinematical and mechanical properties. We show that incorporating multiple cells of the same type but with different geometry could significantly enrich the self-locking origami pattern design. Meanwhile, it offers remarkable programmability to the kinematical properties of the self-locking origami structures, including the number and position of locking points, and the deformation range. Self-locking will also affect the mechanical characteristics of the origami structures. Experiments and finite element simulations reveal that the structural stiffness will experience a sudden jump with the occurrence of self-locking, inducing a piecewise stiffness profile. The results of this research would provide design guidelines for developing self-locking origami structures and metamaterials with excellent kinematical and stiffness characteristics, with many potential engineering applications.

scholarly journals Mechanical characteristics of beta sheet-forming peptide hydrogels are dependent on peptide sequence, concentration and buffer composition

2018 ◽  
Vol 5 (3) ◽  
pp. 171562 ◽  
Author(s):  
Franziska Koch ◽  
Michael Müller ◽  
Finja König ◽  
Nina Meyer ◽  
Jasmin Gattlen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Network Formation ◽  
The Self ◽  
Peptide Sequence ◽  
Beta Sheet ◽  
Self Assembling ◽  
Buffer Composition ◽  
Peptide Hydrogels ◽  
Peptide Hydrogel

Self-assembling peptide hydrogels can be modified regarding their biodegradability, their chemical and mechanical properties and their nanofibrillar structure. Thus, self-assembling peptide hydrogels might be suitable scaffolds for regenerative therapies and tissue engineering. Owing to the use of various peptide concentrations and buffer compositions, the self-assembling peptide hydrogels might be influenced regarding their mechanical characteristics. Therefore, the mechanical properties and stability of a set of self-assembling peptide hydrogels, consisting of 11 amino acids, made from four beta sheet self-assembling peptides in various peptide concentrations and buffer compositions were studied. The formed self-assembling peptide hydrogels exhibited stiffnesses ranging from 0.6 to 205 kPa. The hydrogel stiffness was mostly affected by peptide sequence followed by peptide concentration and buffer composition. All self-assembling peptide hydrogels examined provided a nanofibrillar network formation. A maximum self-assembling peptide hydrogel dissolution of 20% was observed for different buffer solutions after 7 days. The stability regarding enzymatic and bacterial digestion showed less degradation in comparison to the self-assembling peptide hydrogel dissolution rate in buffer. The tested set of self-assembling peptide hydrogels were able to form stable scaffolds and provided a broad spectrum of tissue-specific stiffnesses that are suitable for a regenerative therapy.

Thermal and mechanical characteristics of cement nanocomposites

2013 ◽  
Vol 20 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Mostafa Jalal ◽  
Esmaeel Mansouri
Keyword(s):  
Mechanical Properties ◽  
Thermogravimetric Analysis ◽  
Mechanical Characteristics ◽  
The Self ◽  
Cementitious Composites ◽  
Strength Development ◽  
Thermal And Mechanical Properties ◽  
Conduction Calorimetry ◽  
Different Types ◽  
Flexural Tests

AbstractWidespread applications and advantages of different types of composite materials have drawn researchers’ attention toward the science and technology of composites. Among these materials, cementitious composites have a special place, as they have many applications in various fields of structural and civil engineering. Due to the importance of cementitious composites and their behavior, investigation of their properties is of great importance. Thus in the present study, thermal and mechanical properties of the self-compacting cementitious composites containing different fractions of nano TiO2 have been investigated. Mechanical properties were assessed through compressive, split tensile and flexural tests. The thermal properties were assessed through thermogravimetric analysis (TGA) and conduction calorimetry tests. Accelerated peak appearance in conduction calorimetry tests and more weight loss in thermogravimetric analysis could indicate that TiO2 nanoparticles could lead to strength development at earlier ages and improve the properties of the self-compacting cementitious composites.

Weldability - Behavior of Welded Reinforcement

2019 ◽  
Vol 70 (10) ◽  
pp. 3469-3472
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Current Work ◽  
Carbon Equivalent ◽  
Work Process ◽  
Ultimate Limit

Weldability involves two aspects: welding behavior of components and safety in operation. The two aspects will be reduced to the mechanical characteristics of the elements and to the chemical composition. In the case of steel reinforcing rebar’s, it is reduces to the percentage of Cech(carbon equivalent) and to the mechanical characteristics: the yielding limit, the ultimate limit, and the elongations which after that represent the ductility class in which the re-bars is framed. The paper will present some types of steel reinforcing rebar’s with its mechanical characteristics and the welding behavior of those elements. In the current work, process-related behavior of welded reinforcement, joint local and global mechanical properties, and their correlation with behavior of normal reinforcement and also the mechanical performance resulted in this type of joints. Keywords: welding behavior, ultimate limit, reinforcing rebar’s

scholarly journals Modification of Mechanical Properties of High-Strength Titanium Alloys VT23 and VT23M Due to Impact-Oscillatory Loading

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 80 ◽  
Author(s):  
Mykola Chausov ◽  
Janette Brezinová ◽  
Andrii Pylypenko ◽  
Pavlo Maruschak ◽  
Liudmyla Titova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
High Strength ◽  
The Self ◽  
Self Organization ◽  
Two Phase ◽  
Rolled Metal ◽  
Technological Method ◽  
Equilibrium Processes ◽  
Production Conditions

A simple technological method is proposed and tested experimentally, which allows for the improvement of mechanical properties in sheet two-phase high-strength titanium alloys VT23 and VT23M on the finished product (rolled metal), due to impact-oscillatory loading. Under impact-oscillatory loading and dynamic non-equilibrium processes (DNP) are realized in titanium alloys, leading to the self-organization of the structure. As a result, the mechanical properties of titanium alloys vary significantly with subsequent loading after the realization of DNP. In this study, the test modes are found, which can be used in the production conditions.

scholarly journals Mimicking the Mechanical Properties of Aortic Tissue with Pattern-Embedded 3D Printing for a Realistic Phantom

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5042
Author(s):  
Jaeyoung Kwon ◽  
Junhyeok Ock ◽  
Namkug Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
3D Printing ◽  
Mechanical Characteristics ◽  
Aortic Wall ◽  
Tensile Tests ◽  
Human Aorta ◽  
Aortic Tissue ◽  
Medical Field ◽  
Base Materials

3D printing technology has been extensively applied in the medical field, but the ability to replicate tissues that experience significant loads and undergo substantial deformation, such as the aorta, remains elusive. Therefore, this study proposed a method to imitate the mechanical characteristics of the aortic wall by 3D printing embedded patterns and combining two materials with different physical properties. First, we determined the mechanical properties of the selected base materials (Agilus and Dragonskin 30) and pattern materials (VeroCyan and TPU 95A) and performed tensile testing. Three patterns were designed and embedded in printed Agilus–VeroCyan and Dragonskin 30–TPU 95A specimens. Tensile tests were then performed on the printed specimens, and the stress-strain curves were evaluated. The samples with one of the two tested orthotropic patterns exceeded the tensile strength and strain properties of a human aorta. Specifically, a tensile strength of 2.15 ± 0.15 MPa and strain at breaking of 3.18 ± 0.05 mm/mm were measured in the study; the human aorta is considered to have tensile strength and strain at breaking of 2.0–3.0 MPa and 2.0–2.3 mm/mm, respectively. These findings indicate the potential for developing more representative aortic phantoms based on the approach in this study.

scholarly journals Electromagnetic Interference Shielding and Physical-Mechanical Characteristics of Rubber Composites Filled with Manganese-Zinc Ferrite and Carbon Black

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 616
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Klaudia Hložeková ◽  
Rastislav Dosoudil ◽  
Marek Gořalík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Zinc Ferrite ◽  
Mechanical Characteristics ◽  
Hybrid Composites ◽  
Rubber Matrix ◽  
Butadiene Rubber ◽  
Frequency Range ◽  
Manganese Zinc ◽  
Manganese Zinc Ferrite

In the present work, composite materials were prepared by incorporation of manganese-zinc ferrite, carbon black and combination of ferrite and carbon black into acrylonitrile-butadiene rubber (NBR). For cross-linking of composites, standard sulfur-based curing system was applied. The main goal was to investigate the influence of the fillers on the physical-mechanical properties of composites. Then, the electromagnetic absorption shielding ability was investigated in the frequency range 1 MHz–3 GHz. The results revealed that composites filled with ferrite provide sufficient absorption shielding performance in the tested frequency range. On the other hand, ferrite behaves as an inactive filler and deteriorates the physical-mechanical characteristics of composites. Carbon black reinforces the rubber matrix and contributes to the improvement of physical-mechanical properties. However, composites filled with carbon black are not able to absorb electromagnetic radiation in the given frequency range. Finally, the combination of carbon black and ferrite resulted in the modification of both physical-mechanical characteristics and absorption shielding ability of hybrid composites.

scholarly journals The Effect of Superabsorbent Polymers on the Microstructure and Self-Healing Properties of Cementitious-Based Composite Materials

2021 ◽  
Vol 11 (2) ◽  
pp. 700
Author(s):  
Irene A. Kanellopoulou ◽  
Ioannis A. Kartsonakis ◽  
Costas A. Charitidis
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Hybrid Structure ◽  
The Self ◽  
Self Healing ◽  
Cementitious Composite ◽  
Superabsorbent Polymers ◽  
Porosity Reduction ◽  
Environment Control ◽  
The Impact

Cementitious structures have prevailed worldwide and are expected to exhibit further growth in the future. Nevertheless, cement cracking is an issue that needs to be addressed in order to enhance structure durability and sustainability especially when exposed to aggressive environments. The purpose of this work was to examine the impact of the Superabsorbent Polymers (SAPs) incorporation into cementitious composite materials (mortars) with respect to their structure (hybrid structure consisting of organic core—inorganic shell) and evaluate the microstructure and self-healing properties of the obtained mortars. The applied SAPs were tailored to maintain their functionality in the cementitious environment. Control and mortar/SAPs specimens with two different SAPs concentrations (1 and 2% bwoc) were molded and their mechanical properties were determined according to EN 196-1, while their microstructure and self-healing behavior were evaluated via microCT. Compressive strength, a key property for mortars, which often degrades with SAPs incorporation, in this work, practically remained intact for all specimens. This is coherent with the porosity reduction and the narrower range of pore size distribution for the mortar/SAPs specimens as determined via microCT. Moreover, the self-healing behavior of mortar-SAPs specimens was enhanced up to 60% compared to control specimens. Conclusively, the overall SAPs functionality in cementitious-based materials was optimized.

Development of Heat Treatment Mode with Quenching in Different Quenching Environments for the Casing Pipe in Order to Obtain the Required Mechanical Properties

2020 ◽  
Vol 836 ◽  
pp. 41-45
Author(s):  
S.N. Dzhabbarov ◽  
E.I. Pryakhin
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Characteristics ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Treatment Mode ◽  
Gas Industry ◽  
Heat Treatment Mode ◽  
Optimal Technology ◽  
Casing Pipe

Development of an optimal technology of heat treatment for blanks of the casing pipe made of steel 40H (GOST 4543) is used in the oil and gas industry for casing. It is accompanied by quenching in various environments to ensure guaranteed obtainment of the required mechanical characteristics. These characteristics are specified in GOST 632-80 and met in order to improve the properties of the 40H steel.

Effect of wood particulate size on the mechanical properties of PLA biocomposite

2020 ◽  
Vol 49 (6) ◽  
pp. 465-472
Author(s):  
S. Raj Sachin ◽  
T. Kandasamy Kannan ◽  
Rathanasamy Rajasekar
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Wood Flour ◽  
Wood Particle ◽  
Poly Lactic Acid ◽  
Particle Sizes ◽  
Content Type ◽  
Particulate Size ◽  
Practical Implications

Purpose The purpose of this study is to carry out an investigation of the role of the wood particle size on the mechanical properties of poly lactic acid (PLA)-reinforced neem fiber biocomposite. Design/methodology/approach Composite test specimens were processed by reinforcing neem wood flour (NWF) in two different particle sizes, micro-sized NWF (MNWF) and nano-sized NWF (NNWF) separately into PLA. Composites were extruded at four different fiber loadings (10, 15, 20 and 25 Wt.%) into PLA matrix. The MNWF and NNWF had particle sizes varying from 5 to 15 µm and 10 to 15 nm, respectively. Findings Tensile strength, flexural strength and impact strength of PLA increased with fiber reinforcement for both the MNWF and NNWF cases. The NNWF-reinforced PLA composite at 20 Wt.% fiber loading proved to be the best composite that had outstanding mechanical properties in this research. Practical implications The developed composite can be used as a substitute for conventional plywood for furniture, building infrastructure and interior components for the automobile, aircraft and railway sectors. Originality/value A new biocomposite had been fabricated by using PLA and NWF and had been tested for its mechanical characteristics.

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