Applying the Hashin–Shtrikman bounds to predict stiffness of multicomponent 3D printed structures: Towards regenerative orthopaedic medicine

2019 ◽  
Vol 54 (16) ◽  
pp. 2173-2183
Author(s):  
Georgio A Katsifis ◽  
David R McKenzie ◽  
Natalka Suchowerska
Keyword(s):  
Mechanical Properties ◽  
Polymer Materials ◽  
Isotropic Composite ◽  
Metallic Implants ◽  
Three Phase ◽  
Implant Size ◽  
3D Printed ◽  
Orthopaedic Medicine ◽  
Lower Limits

Customised orthopaedic implants made from polymer materials would have advantages over metallic implants, if the mechanical properties could be matched more closely to bone. Here, the Hashin–Shtrikman bounds for isotropic composites are used to examine the feasibility of using scaffolds made from 3D printed polyether–etherketone (PEEK) that may adequate modulus immediately after printing, but when integrated and mineralised could approach the modulus of bone. The ability to predict the mechanical properties of 3D printed objects is essential for skeletal implants that require both immediate and long-term strength, such as the mandible and the femur. However, there is no method for predicting the change in mechanical properties due to the effect of ossification of bone scaffolds. Our aim was to calculate the upper and lower limits of the elastic moduli of polymer composites using the Hashin–Shtrikman bounds for isotropic composite solids and use them to compare the pre- and post-ossification properties for a range of scaffolds. We describe 3D printed PEEK as a composite of fully dense PEEK and air, water or bone. We confirm, by mechanically testing three designs, that our 3D printed scaffolds lie within the Hashin–Shtrikman bounds for PEEK–air composites. Improvements in strength achieved by integrating the PEEK scaffold with bone are predicted by calculating the Hashin–Shtrikman bounds for a three-phase composite and show the feasability of reaching bone equivalence. These predictions can be implemented for orthopaedic applications, customising the implant such that it can provide the appropriate immediate and long-term mechanical support for a specific implant size.

Experimental Investigation on the Electrical and Dynamic Mechanical Properties of PMN/Electrically Conductive Carbon Black/Butyl Composites

2007 ◽  
Vol 351 ◽  
pp. 171-175 ◽  
Author(s):  
Yan Bing Wang ◽  
Zhi Xiong Huang ◽  
Yan Qin ◽  
Ming Du ◽  
Lian Meng Zhang
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Loss Factor ◽  
Dynamic Mechanical Properties ◽  
Polymer Materials ◽  
Electrically Conductive ◽  
Dynamic Mechanical ◽  
Temperature Range ◽  
Conductive Carbon Black ◽  
Three Phase

In this paper, a three-phase composite with electrically conductive carbon black (ECCB) and piezoelectric ceramic particles, PMN, embedded into butyl (PMN/ECCB/IIR) was prepared by simple blend and mold-press process. Dynamic mechanical properties with various ECCB loading were tested by dynamic mechanical analysis (DMA). DMA shows that the ECCB loading has remarkable effect on the dynamic mechanical properties of the three-phase composite. The temperature range of loss factor (tanδ) above 0.3 the composite was broadened by almost 100°C and the maximum of loss factor shifts to higher temperature in the testing temperature range respectively with increasing the ECCB loading. The piezoelectric damping theory was used to explain the experimental results. The three-phase composites with proper composition can be used as high damping polymer materials.

Investigation of future 3D printed brace design parameters: evaluation of mechanical properties and prototype outcomes

2019 ◽  
Vol 3 (4) ◽  
pp. 171-184
Author(s):  
Kenwick JL Ng ◽  
Kajsa Duke ◽  
Edmond Lou
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Treatment Effectiveness ◽  
Design Parameters ◽  
Wear Comfort ◽  
Polypropylene Material ◽  
Spinal Brace ◽  
3D Printed ◽  
Opening And Closing

Aim: Spinal brace wear time affects treatment effectiveness of adolescent idiopathic scoliosis but remains challenging with the brace’s bulkiness. This study aims to determine the appropriate material and thickness to improve wear comfort. Materials & methods: Thirty-one specimens were tested with 13 ULTEM1010 and 13 Nylon12 potential materials and 5 standard polypropylene material in 2.5, 3.25 and 4 mm thicknesses to evaluate mechanical properties. Donning tests of ULTEM1010 and Nylon12 printed braces were conducted. Results: Nylon12 with 2.5–3.25 mm thickness had higher flexibility and the closest mechanical characteristics as 4-mm thick polypropylene. ULTEM1010 brace fractured after 615-times and Nylon12 brace handled 2920-times of opening and closing. Conclusion: Nylon12, 2.5–3.25 mm are appropriate design parameters. Further clinical study can validate long term brace effectiveness.

scholarly journals Development of Weather-Resistant 3D Printed Structures by Multi-Material Additive Manufacturing

2020 ◽  
Vol 4 (3) ◽  
pp. 94 ◽  
Author(s):  
Arash Afshar ◽  
Roy Wood
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Structural Integrity ◽  
Low Cost ◽  
Acrylonitrile Butadiene Styrene ◽  
Outdoor Environments ◽  
3D Printed ◽  
Novel Method ◽  
Structural Surface

Additive manufacturing, or 3D printing, has had a big impact on the manufacturing world through its low cost, material recyclability, and fabrication of intricate geometries with a high resolution. Three-dimensionally printed polymer structures in aerospace, marine, construction, and automotive industries are usually intended for service in outdoor environments. During long-term exposures to harsh environmental conditions, the mechanical properties of these structures can be degraded significantly. Developing coating systems for 3D printed parts that protect the structural surface against environmental effects and provide desired surface properties is crucial for the long-term integrity of these structures. In this study, a novel method was presented to create 3D printed structures coated with a weather-resistant material in a single manufacturing operation using multi-material additive manufacturing. One group of specimens was 3D printed from acrylonitrile-butadiene-styrene (ABS) material and the other group was printed from ABS and acrylic-styrene-acrylonitrile (ASA) as a substrate and coating material, respectively. The uncoated ABS specimens suffered significant degradation in the mechanical properties, particularly in the failure strain and toughness, during exposure to UV radiation, moisture, and high temperature. However, the ASA coating preserved the mechanical properties and structural integrity of ABS 3D printed structures in aggressive environments.

Long-Term Creep and Impact Strength of Biocompatible 3D-Printed PLA-Based Scaffolds

2017 ◽  
Vol 13 ◽  
pp. 15-20 ◽  
Author(s):  
Kirill V. Niaza ◽  
Fedor S. Senatov ◽  
Andrey Stepashkin ◽  
Natalia Yu. Anisimova ◽  
Mikhail V. Kiselevsky
Keyword(s):  
Mechanical Properties ◽  
Charpy Impact ◽  
Bone Defects ◽  
Porous Scaffolds ◽  
Fabrication Method ◽  
Fused Filament Fabrication ◽  
3D Printed ◽  
Term Creep ◽  
Small Bone

In the present work porous scaffolds for trabecular bone defects replacement were studied. PLA and PLA/HA сomposites were obtained by extrusion. Scaffolds were obtained by 3D-printing by fused filament fabrication method. Long-term creep and Charpy impact tests show that PLA/HA scaffolds with the maximum force for destruction at impact of 119 N can function under a load of up to 10 MPa without shape changing and loss of mechanical properties. In vivo tests were used to investigate biocompatibility of scaffolds. The scaffolds may be used as implants for unloaded small bone defects replacement

Modelling of changes in physical and mechanical properties of structural materials during long-term exposures at elevated temperatures

2004 ◽  
Vol 120 ◽  
pp. 191-199
Author(s):  
J. Kohout
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Physical And Mechanical Properties ◽  
Structural Materials ◽  
Experimental Results ◽  
Polymer Materials ◽  
Polyamide 66 ◽  
Glass Fibre Reinforced

Long-term exposures of various industrial structural materials at sufficiently elevated temperatures cause substantial changes in materials structures and, consequently, substantial changes in their physical and materials properties. The paper is focused to the influence of thermodegradation of glass-fibre-reinforced polyamide 66 in dry air and gear oil on its mechanical properties. As the thermodegradation of polymer materials is diffusion controlled process, the paper starts with the description of water diffusion in tested material. Then a very simple degradation mechanism is proposed for modelling the main features of real degradation processes. Regression functions describing the changes in mechanical properties of polyamide details during exposure are verified by the fit of experimental results. In the end of the paper some general considerations about the changes in other structural materials during exposures are done and supported by some experimental results.

Possibilities of using biodegradable polymeric materials in the agricultural sector

2020 ◽  
Vol 67 (2) ◽  
pp. 115-120
Author(s):  
Raisa A. Alekhina ◽  
Victoriya E. Slavkina ◽  
Yuliya A. Lopatina
Keyword(s):  
Mechanical Properties ◽  
Biodegradable Polymers ◽  
Biodegradable Polymer ◽  
Agricultural Sector ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Limiting Factors ◽  
Research Purpose ◽  
Biodegradable Materials ◽  
Advantages And Disadvantages

The article presents options for recycling polymers. The use of biodegradable materials is promising. This is a special class of polymers that can decompose under aerobic or anaerobic conditions under the action of microorganisms or enzymes forming natural products such as carbon dioxide, nitrogen, water, biomass, and inorganic salts. (Research purpose) The research purpose is in reviewing biodegradable materials that can be used for the manufacture of products used in agriculture. (Materials and methods) The study are based on open information sources containing information about biodegradable materials. Research methods are collecting, studying and comparative analysis of information. (Results and discussion) The article presents the advantages and disadvantages of biodegradable materials, mechanical properties of the main groups of biodegradable polymers. The article provides a summary list of agricultural products that can be made from biodegradable polymer materials. It was found that products from the general group are widely used in agriculture. Authors have found that products from a special group can only be made from biodegradable polymers with a controlled decomposition period in the soil, their use contributes to increasing the productivity of crops. (Conclusions) It was found that biodegradable polymer materials, along with environmental safety, have mechanical properties that allow them producing products that do not carry significant loads during operation. We have shown that the creation of responsible products (machine parts) from biodegradable polymers requires an increase in their strength properties, which is achievable by creating composites based on them. It was found that the technological complexity of their manufacture and high cost are the limiting factors for the widespread use of biodegradable polymers at this stage.

Micro-Hardness and Morphology of LDPE Influenced by Beta Radiation

2014 ◽  
Vol 606 ◽  
pp. 253-256 ◽  
Author(s):  
Martin Ovsik ◽  
Petr Kratky ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hardness Test ◽  
Polymer Materials ◽  
Beta Radiation ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Depth Sensing ◽  
Surface Layers ◽  
Hardness Values ◽  
Different Doses

This article deals with the influence of different doses of Beta radiation to the structure and mico-mechanical properties of Low-density polyethylene (LDPE). Hard surface layers of polymer materials, especially LDPE, can be formed by radiation cross-linking by β radiation with doses of 33, 66 and 99 kGy. Material properties created by β radiation are measured by micro-hardness test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the LDPE tested. The highest values of micro-mechanical properties were reached at radiation dose of 66 and 99 kGy, when the micro-hardness values increased by about 21%. The changes were examined and confirmed by X-ray diffraction.

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