Multidimensional Mechanics of Three-Dimensional Printed and Micro-Architectured Scaffolds

2021 ◽  
Vol 88 (10) ◽  
Author(s):  
Pooya Niksiar ◽  
Zhaoxu Meng ◽  
Michael M. Porter
Keyword(s):  
Mechanical Properties ◽  
Wall Thickness ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Freeze Casting ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Buckling Resistance ◽  
Architectural Characteristics

Abstract Mechanical properties of porous materials depend on their micro-architectural characteristics. Freeze casting is an effective method to fabricate micro-architectured porous scaffolds. Three key characteristics generated during freeze casting are wall thickness, number of domains at the cross section, and transverse bridges connecting adjacent walls. To specifically study the effect of these structural characteristics on the mechanics and anisotropic compressive properties of scaffolds, we utilize additive manufacturing, i.e., 3D printing, to fabricate strictly designed cubic scaffolds with varying one characteristic at a time. We then compare strength, toughness, resilience, stiffness, and strain to failure in three orthogonal directions of the scaffolds, including longitudinal and transverse directions. To compare these multidimensional mechanics in a single diagram, we use a previously developed radar chart method to evaluate different scaffolds and unravel the effect of the structural characteristics. We find that the multidimensional mechanics can be effectively tuned by the micro-architectural characteristics. Notably, the buckling resistance of the scaffolds depends on all three structural characteristics. Our results show that an increased number of domains leads to enhanced toughness in all three directions. Increasing wall thickness leads to enhanced mechanical properties but comes at the price of losing small-sized pores, which is not favored for certain applications. In addition, adding transverse bridges increases not only the transverse strength of the scaffolds but also the longitudinal strength as they also enhance the buckling resistance. Our study provides important insights into the structure–property relationships of 3D-printed micro-architectured porous scaffolds.

scholarly journals Numerical simulation of dual-phase steel based on real and virtual three-dimensional microstructures

2021 ◽  
Author(s):  
Frederik Scherff ◽  
Jessica Gola ◽  
Sebastian Scholl ◽  
Kinshuk Srivastava ◽  
Thorsten Staudt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Simulation Model ◽  
Dual Phase Steel ◽  
Three Dimensional ◽  
Simultaneous Increase ◽  
Dual Phase ◽  
Structure Property ◽  
Heavy Plate ◽  
Property Correlation ◽  
Process Route

AbstractDual-phase steel shows a strong connection between its microstructure and its mechanical properties. This structure–property correlation is caused by the composition of the microstructure of a soft ferritic matrix with embedded hard martensite areas, leading to a simultaneous increase in strength and ductility. As a result, dual-phase steels are widely used especially for strength-relevant and energy-absorbing sheet metal structures. However, their use as heavy plate steel is also desirable. Therefore, a better understanding of the structure–property correlation is of great interest. Microstructure-based simulation is essential for a realistic simulation of the mechanical properties of dual-phase steel. This paper describes the entire process route of such a simulation, from the extraction of the microstructure by 3D tomography and the determination of the properties of the individual phases by nanoindentation, to the implementation of a simulation model and its validation by experiments. In addition to simulations based on real microstructures, simulations based on virtual microstructures are also of great importance. Thus, a model for the generation of virtual microstructures is presented, allowing for the same statistical properties as real microstructures. With the help of these structures and the aforementioned simulation model, it is then possible to predict the mechanical properties of a dual-phase steel, whose three-dimensional (3D) microstructure is not yet known with high accuracy. This will enable future investigations of new dual-phase steel microstructures within a virtual laboratory even before their production.

Novel Ultrasonic Technology for Devulcanization of Waste Rubbers

1995 ◽  
Vol 68 (2) ◽  
pp. 267-280 ◽  
Author(s):  
A. I. Isayev ◽  
J. Chen ◽  
A. Tukachinsky
Keyword(s):  
Mechanical Properties ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Ultrasonic Waves ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Processing Conditions ◽  
Laboratory Reactor ◽  
Plant Level ◽  
Theological Properties

Abstract A novel patented process and several reactors have been developed for devulcanization of waste rubbers. The technology is based on the use of the high power ultrasonics. The ultrasonic waves of certain levels in the presence of pressure and heat rapidly break up the three-dimensional network in crosslinked rubbers. The devulcanized rubber can be reprocessed, shaped and revulcanized in much the same way as a virgin rubber. The first laboratory reactor has been scaled up to pilot-plant level by the National Feedscrew and Machining, Inc. Various devulcanization experiments were carried out with model styrene-butadiene rubber (SBR) and with ground rubber tire (GRT). Curing behavior, Theological properties, and structural characteristics of rubbers devulcanized at various processing conditions were studied, as well as mechanical properties of revulcanized rubber samples. A possible mechanism of the devulcanization is discussed. The performed measurements indicate that the rubbers are partially devulcanized, and the devulcanization process is accompanied by certain degradation of the macromolecular chains. In spite of these observations, the processing conditions are identified at which the retention of the mechanical properties is found to be good. A further work is in progress to find the optimal conditions of devulcanization and to improve the selectivity of the process towards breaking up the chemical network only.

“Wet-state” mechanical properties of three-dimensional polyester porous scaffolds

2005 ◽  
Vol 76A (2) ◽  
pp. 264-271 ◽  
Author(s):  
Linbo Wu ◽  
Junchuan Zhang ◽  
Dianying Jing ◽  
Jiandong Ding
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Porous Scaffolds

scholarly journals Sintering Behavior of a Six-Oxide Silicate Bioactive Glass for Scaffold Manufacturing

2020 ◽  
Vol 10 (22) ◽  
pp. 8279
Author(s):  
Elisa Fiume ◽  
Gianpaolo Serino ◽  
Cristina Bignardi ◽  
Enrica Verné ◽  
Francesco Baino
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Tissue Repair ◽  
Sintering Temperature ◽  
Thermal Analyses ◽  
Three Dimensional ◽  
Sintering Behavior ◽  
Porous Scaffolds ◽  
Bioactive Glasses ◽  
Different Temperatures

The intrinsic brittleness of bioactive glasses (BGs) is one of the main barriers to the widespread use of three-dimensional porous BG-derived bone grafts (scaffolds) in clinical practice. Among all the available strategies for improving the mechanical properties of BG-based scaffolds, strut densification upon sintering treatments at high temperatures represents a relatively easy approach, but its implementation might lead to undesired and poorly predictable decrease in porosity, mass transport properties and bioactivity resulting from densification and devitrification phenomena occurring in the material upon heating. The aim of the present work was to investigate the sinter-crystallization of a highly bioactive SiO2-P2O5-CaO–MgO–Na2O–K2O glass (47.5B composition) in reference to its suitability for the fabrication of bonelike foams. The thermal behavior of 47.5B glass particles was investigated upon sintering at different temperatures in the range of 600–850 °C by means of combined thermal analyses (differential thermal analysis (DTA) and hot-stage microscopy (HSM)). Then, XRD measurements were carried out to identify crystalline phases developed upon sintering. Finally, porous scaffolds were produced by a foam replica method in order to evaluate the effect of the sintering temperature on the mechanical properties under compression loading conditions. Assessing a relationship between mechanical properties and sintering temperature, or in other words between scaffold performance and fabrication process, is a key step towards the rationale design of optimized scaffolds for tissue repair.

QSPR STUDY OF RHEOLOGICAL AND MECHANICAL PROPERTIES OF CHLOROPRENE RUBBER ACCELERATORS

2014 ◽  
Vol 87 (2) ◽  
pp. 219-238 ◽  
Author(s):  
Roberto Todeschini ◽  
Viviana Consonni ◽  
Davide Ballabio ◽  
Andrea Mauri ◽  
Matteo Cassotti ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mathematical Models ◽  
Structural Features ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Quantitative Structure Property Relationships ◽  
Cure Time ◽  
Chloroprene Rubber ◽  
Experimental Values ◽  
Rubber Accelerators

ABSTRACT In this preliminary study, mathematical models based on Quantitative Structure Property Relationships (QSPR) were applied in order to analyze how molecular structure of chloroprene rubber accelerators relates to their rheological and mechanical properties. QSPR models were developed in order to disclose which structural features mainly affect the mechanism of vulcanization. In such a way QSPR can help in a faster and more parsimonious design of new chloroprene rubber curative molecules. Regression mathematical models were calibrated on two rheological properties (scorch time and optimum cure time) and three mechanical properties (modulus 100%, hardness, and elongation at break). Models were calculated using experimental values of 14 accelerators belonging to diverse chemical classes and validated by means of different strategies. All the derived models gave a good degree of fitting (R2 values ranging from 84.5 to 98.7) and a satisfactory predictive power. Moreover, some hypotheses on the correlations between specific structural features and the analyzed rheological and mechanical properties were drawn. Owing to the relatively small set of accelerators used to calibrate the models, these hypotheses should be further investigated and proved.

X-ray microtomographic imaging and analysis for basic research

2006 ◽  
Vol 21 (2) ◽  
pp. 125-131 ◽  
Author(s):  
J. H. Dunsmuir ◽  
S. Bennett ◽  
L. Fareria ◽  
A. Mingino ◽  
M. Sansone
Keyword(s):  
Spatial Resolution ◽  
Three Dimensional ◽  
Basic Research ◽  
Integrated Approach ◽  
Imaging Method ◽  
Structure Property ◽  
3D Images ◽  
X Ray ◽  
Structure Property Relationships ◽  
Essential Components

For research facilities with access to synchrotron X-ray sources, X-ray absorption microtomography (XMT) has evolved from an experimental imaging method to a specialized, if not yet routine, microscopy for imaging the three-dimensional (3D) distribution of linear attenuation coefficients and, in some cases, elemental concentration with micron spatial resolution. Recent advances in source and detector design have produced conventional X-ray source instruments with comparable spatial resolution but with lower throughput and without element specific imaging. Both classes of instrument produce 3D images for analysis. We discuss an integrated approach for the implementation of analytical XMT to support basic research into the structure-property relationships of a variety of materials. The essential components include instrumentation for collecting quantitative 3D images, a 3D image processing environment to address questions as to the quantity, composition, geometry, and relationships among the features in one or more images, and visualization to provide insight and communicate results. We give examples of image analysis of resolved and unresolved pore spaces of sandstones.

Efficiently mapping structure–property relationships of gas adsorption in porous materials: application to Xe adsorption

2017 ◽  
Vol 201 ◽  
pp. 221-232 ◽  
Author(s):  
A. R. Kaija ◽  
C. E. Wilmer
Keyword(s):  
Porous Materials ◽  
Void Fraction ◽  
Large Scale ◽  
Gas Adsorption ◽  
Structural Characteristics ◽  
Gas Storage ◽  
Computational Method ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Computational Screening

Designing better porous materials for gas storage or separations applications frequently leverages known structure–property relationships. Reliable structure–property relationships, however, only reveal themselves when adsorption data on many porous materials are aggregated and compared. Gathering enough data experimentally is prohibitively time consuming, and even approaches based on large-scale computer simulations face challenges. Brute force computational screening approaches that do not efficiently sample the space of porous materials may be ineffective when the number of possible materials is too large. Here we describe a general and efficient computational method for mapping structure–property spaces of porous materials that can be useful for adsorption related applications. We describe an algorithm that generates random porous “pseudomaterials”, for which we calculate structural characteristics (e.g., surface area, pore size and void fraction) and also gas adsorption properties via molecular simulations. Here we chose to focus on void fraction and Xe adsorption at 1 bar, 5 bar, and 10 bar. The algorithm then identifies pseudomaterials with rare combinations of void fraction and Xe adsorption and mutates them to generate new pseudomaterials, thereby selectively adding data only to those parts of the structure–property map that are the least explored. Use of this method can help guide the design of new porous materials for gas storage and separations applications in the future.

scholarly journals MEASURING INFLUENCE OF DYNAMIC CHARACTERISTICS OF MIXERS ON STRUCTURAL AND MECHANICAL PROPERTIES OF MINCED FISH

2020 ◽  
Vol 0 (1) ◽  
pp. 138-144
Author(s):  
Viktor Vladimirovich Kogan
Keyword(s):  
Mechanical Properties ◽  
Dynamic Characteristics ◽  
Raw Materials ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Angular Speed ◽  
Three Dimensional Flow ◽  
Minced Fish ◽  
The Relationship

The article presents the empirical results of estimating the dependence of viscoplastic properties of the minced ordinary fish raw materials from the kinematic and dynamic characteristics of mechanisms applied in the course of processing. When mixed in mechanical mixers, minced fish is subjected to shear and normal effects of rotating parts that create a complex three-dimensional flow. Optimization of the process of obtaining viscous-plastic culinary products depends on the dynamics of movement of the studied objects and the influence of working parts of various configurations. To establish the relationship between the duration of mixing, the angular speed of rotation of the working part of the horizontal mixer and general structural and mechanical properties of minced fish, there were carried out experimental studies using various types of mixer working parts: conveyer, screw and blade. The influence of the rotation speed of the mixer working part on the change in the rheological characteristics of the investigated raw materials has been confirmed. Specific energy costs should be emphasized as one of the main criteria for evaluating the performance of the supporting equipment. This parameter depends on redistribution of components during their mixing, changes in the structural and mechanical properties of minced fish and structural characteristics of the working parts. It has been stated that the lowest energy consumption and optimal mode for viscoplastic mixed mass can be achieved by using blades with an inclination angle to the axis of rotation = 20–30° and a humidity increase of mixed mass up to 0.7–0.8 kg/kg.

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