scholarly journals Extraction of Anisotropic Mechanical Properties From Nanoindentation of SiC-6H Single Crystals

2016 ◽  
Vol 83 (9) ◽  
Author(s):  
Amit Datye ◽  
Lin Li ◽  
Wei Zhang ◽  
Yujie Wei ◽  
Yanfei Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Mechanical Behavior ◽  
Peak Load ◽  
Contact Analysis ◽  
Elastic Contact ◽  
Wide Range ◽  
Anisotropic Mechanical Properties ◽  
Anisotropic Elastic ◽  
The Relationship

Because brittle solids fail catastrophically during normal tension and compression testing, nanoindentation is often a useful alternative technique for measuring their mechanical properties and assessing their deformation characteristics. One practical question to be addressed in such studies is the relationship between the anisotropy in the uniaxial mechanical behavior to that in the indentation response. To this end, a systematic study of the mechanical behavior the 6H polytype of a hexagonal silicon carbide single crystal (SiC-6H) was performed using standard nanoindentation methods. The indentation elastic modulus and hardness measured using a Berkovich indenter at a peak load of 500 mN varied over a wide range of crystal orientation by only a few percent. The variation in modulus is shown to be consistent with an anisotropic elastic contact analysis based on the known single crystal elastic constants of the material. The variation in hardness is examined using a single crystal plasticity model that considers the anisotropy of slip in hexagonal crystals. When compared to experimental measurements, the analysis confirms that plasticity in SiC-6H is dominated by basal slip. An anisotropic elastic contact analysis provides insights into the relationship between the pop-in load, which characterizes the transition from elasticity to plasticity during nanoindentation testing, and the theoretical strength of the material. The observations and analyses lay the foundations for further examination of the deformation and failure mechanisms in anisotropic materials by nanoindentation techniques.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Cell structure and mechanical properties of microcellular PLA foams prepared via autoclave constrained foaming

2020 ◽  
pp. 026248932093032
Author(s):  
Jinwei Chen ◽  
Ling Yang ◽  
Dahua Chen ◽  
Qunshan Mai ◽  
Meigui Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Size ◽  
Cell Structure ◽  
Saturation Pressure ◽  
Tensile Modulus ◽  
Cell Structures ◽  
Wide Range ◽  
The Mean ◽  
Constrained Foaming ◽  
The Relationship

Microcellular polylactic acid (PLA) foams with various cell size and cell morphologies were prepared using supercritical carbon dioxide (sc-CO2) solid-state foaming to investigate the relationship between the cell structure and mechanical properties. Constrained foaming was used and a wide range of cell structures with a constant porosity of ∼75% by tuning saturation pressure (8–24 MPa) was developed. Experiments varying the saturation pressure while holding other variables’ constant show that the mean cell size and the mean cell wall thickness decreased, while the cell density and the open porosity increased with increase of pressure. Tensile modulus of PLA foams decreased with increasing the saturation pressure, but the specific tensile modulus of PLA foams was still 15–80% higher than that of solid PLA. Tensile strength and elongation at break first increased with increasing saturation pressure up to 16 MPa and then decreased with further increasing saturation pressure (20 MPa and 24 MPa) at which opened-cell structure produced. Compressive modulus, compressive strength, and compressive yield stress also followed the same variation trend. The results indicated that not only cell size plays an important role in properties of PLA foams but also cell morphology can influence these properties significantly.

Micro pulling down growth of very thin shape memory alloys single crystals

2017 ◽  
Vol 10 (01) ◽  
pp. 1740003 ◽  
Author(s):  
I. López-Ferreño ◽  
J. San Juan ◽  
T. Breczewski ◽  
G. A. López ◽  
M. L. Nó
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Single Crystals ◽  
Functional Materials ◽  
Small Scale ◽  
Cylindrical Shape ◽  
Minimum Diameter ◽  
Wide Range

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu–Al–Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100–200[Formula: see text]C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1[Formula: see text]mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down ([Formula: see text]-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The [Formula: see text]-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200[Formula: see text][Formula: see text]m in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

Characterization of the mechanical behavior of wear surfaces on single crystal nickel by nanomechanical techniques

2009 ◽  
Vol 24 (3) ◽  
pp. 844-852 ◽  
Author(s):  
M.J. Cordill ◽  
N.R. Moody ◽  
S.V. Prasad ◽  
J.R. Michael ◽  
W.W. Gerberich
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Mechanical Behavior ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Surface Deformation ◽  
Ion Beam ◽  
Test Methods ◽  
Strong Increase ◽  
Number Of Cycles

In ductile metals, sliding contact induces plastic deformation resulting in subsurfaces, the mechanical properties of which are different from those of the bulk. This article describes a novel combination of nanomechanical test methods and analysis techniques to evaluate the mechanical behavior of the subsurfaces generated underneath a wear surface. In this methodology, nanoscratch techniques were first used to generate wear patterns as a function of load and number of cycles using a Hysitron TriboIndenter. Measurements were made on a (001) single crystal plane along two crystallographic directions, <001> and <011>. Nanoindentation was then used to measure mechanical properties in each wear pattern. The results on the (001) single crystal nickel plane showed that there was a strong increase in hardness with increasing applied load that was accompanied by a change in surface deformation. The amount of deformation underneath the wear patterns was examined from focused ion beam cross-sections of the wear patterns.

scholarly journals Fabrication and Modeling of Dynamic Multipolymer Nanofibrous Scaffolds

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
Brendon M. Baker ◽  
Nandan L. Nerurkar ◽  
Jason A. Burdick ◽  
Dawn M. Elliott ◽  
Robert L. Mauck
Keyword(s):  
Mechanical Properties ◽  
Rational Design ◽  
Cell Infiltration ◽  
Tissue Properties ◽  
Matrix Deposition ◽  
Native Tissue ◽  
Nanofibrous Scaffolds ◽  
Wide Range ◽  
Anisotropic Mechanical Properties

Aligned nanofibrous scaffolds hold tremendous potential for the engineering of dense connective tissues. These biomimetic micropatterns direct organized cell-mediated matrix deposition and can be tuned to possess nonlinear and anisotropic mechanical properties. For these scaffolds to function in vivo, however, they must either recapitulate the full dynamic mechanical range of the native tissue upon implantation or must foster cell infiltration and matrix deposition so as to enable construct maturation to meet these criteria. In our recent studies, we noted that cell infiltration into dense aligned structures is limited but could be expedited via the inclusion of a distinct rapidly eroding sacrificial component. In the present study, we sought to further the fabrication of dynamic nanofibrous constructs by combining multiple-fiber populations, each with distinct mechanical characteristics, into a single composite nanofibrous scaffold. Toward this goal, we developed a novel method for the generation of aligned electrospun composites containing rapidly eroding (PEO), moderately degradable (PLGA and PCL/PLGA), and slowly degrading (PCL) fiber populations. We evaluated the mechanical properties of these composites upon formation and with degradation in a physiologic environment. Furthermore, we employed a hyperelastic constrained-mixture model to capture the nonlinear and time-dependent properties of these scaffolds when formed as single-fiber populations or in multipolymer composites. After validating this model, we demonstrated that by carefully selecting fiber populations with differing mechanical properties and altering the relative fraction of each, a wide range of mechanical properties (and degradation characteristics) can be achieved. This advance allows for the rational design of nanofibrous scaffolds to match native tissue properties and will significantly enhance our ability to fabricate replacements for load-bearing tissues of the musculoskeletal system.

scholarly journals Determination of Anisotropic Mechanical Properties for Materials Processed by Laser Powder Bed Fusion

2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Even W. Hovig ◽  
Amin S. Azar ◽  
Frode Grytten ◽  
Knut Sørby ◽  
Erik Andreassen
Keyword(s):  
Mechanical Properties ◽  
Transversely Isotropic ◽  
Tensile Tests ◽  
Image Correlation ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Inconel 718 Alloy ◽  
Powder Bed ◽  
Anisotropic Mechanical Properties ◽  
Anisotropic Elastic

Improving the success rate in additive manufacturing and designing highly optimized structures require proper understanding of material behaviour. This study proposes a novel experimental method by which anisotropic mechanical properties of additively manufactured materials can be assessed. The procedure is based on tensile testing of flat specimens, manufactured by laser powder bed fusion (LPBF) at different orientations relative to the build plate. In this study, the procedure was applied to the Inconel 718 alloy. Three identical specimen sets were built, each of which received complementary postprocessing treatments. The tensile tests were carried out on specimens with as-built surface finish. Digital image correlation was used to record the strain field evolution on two perpendicular surfaces of the tensile specimens under loading. An optimization algorithm is also proposed for determining the anisotropic elastic constants using only a few tensile test results. It was observed that both build orientation and postprocessing have strong influence on the anisotropic mechanical properties of the material. The effect of microstructure was also investigated and characterised. Consequently, three transversely isotropic compliance matrices were constructed, representing the effect of the different processing conditions.

A multidisciplinary approach to the engineering of footwear cushioning: A practical example of gym training shoes

2020 ◽  
pp. 175433712095722
Author(s):  
Cédric YM Morio ◽  
Laura Bouten ◽  
Simon Duraffourg ◽  
Nicolas Delattre
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Multidisciplinary Approach ◽  
Wear Test ◽  
Sensory Panel ◽  
Optimal Amount ◽  
Shoe Design ◽  
Wide Range ◽  
The Relationship

According to sports goers, one of the most important features of gym training shoes is their cushioning properties. The optimal amount of cushioning is, however, complex to define. In the present paper, a multi-disciplinary approach was proposed to investigate and determine the optimal perceived midsole cushioning for gym training shoes. Firstly, impact tests were performed to characterise a wide range of shoes representing the gym training shoe market. Trained sensory panel method and mechanical testing were combined to determine the relationship between the perception of cushioning and the shoe’s mechanical properties. Secondly, the preferred cushioning perception was assessed. Then, numerous midsole configurations were tested using finite element method (FEM) to determine the combinations with the best cushioning properties in order to reduce the number of physical prototypes. To assess the best configuration estimated by the numerical model, a wear test was performed as a final validation. From this approach, relationship between the mechanical properties of the midsole and perception of cushioning was found, and an optimal perceived cushioning was identified. Moreover, through FEM numerical simulations, a great number of midsole configurations and designs were tested without making any actual prototypes. Prototype shoes were based on the best numerical solution. The final wear test confirmed that the prototype gym training shoes achieved the preferred perception of cushioning. The present methodology proposes a framework, which empowers the use of athlete’s and exerciser’s perception in shoe design.

scholarly journals On the Relationship between Mechanical Properties and Crystallisation of Chemically Post-Processed Additive Manufactured Polylactic Acid Pieces

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 941 ◽  
Author(s):  
A.P. Valerga ◽  
S.R. Fernandez-Vidal ◽  
F. Girot ◽  
A.J. Gamez
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Maximum Stress ◽  
Fused Deposition Modelling ◽  
Material Behaviour ◽  
Time Consumption ◽  
Fused Deposition ◽  
Wide Range ◽  
Hardness Scale ◽  
The Relationship

Nowadays, improvement of the surface finish of parts manufactured by fused deposition modelling is a well-studied topic. Chemical post-treatments have proven to be the best technique in terms of time consumption and smoothness improvement. However, these treatments modify the structure of the material and, consequently, its mechanical properties. This relationship was studied in this work. In this case, on the basis of a previous study on crystallisation, polylactic acid pieces were subjected to different post-treatments to evaluate their effects on the sample’s mechanical properties, i.e., tensile strength and hardness. Models were obtained according to their percentage of crystallisation, which was related to the different treatments, as well as immersion time. Dramatic changes were obtained within a wide range of material behaviour with some treatments. Specifically, changes were obtained in the maximum stress (from 55 to 20 MPa), in elongation (from 3% to 260%), and in the hardness scale (Shore D to A).

scholarly journals Alternative Liquid Assisted-Sintering of AL/CU Composites Using Selective Powders of AS-Cast Al-ZN Alloy

2022 ◽  
Author(s):  
Eder Lopes Ortiz ◽  
Wislei Riuper Osório ◽  
Ausdinir Danilo Bortolozo ◽  
Giovana da Silva Padilha
Keyword(s):  
Mechanical Properties ◽  
Energy Consumption ◽  
Powder Metallurgy ◽  
Aluminum Alloys ◽  
Mechanical Strength ◽  
Mechanical Behavior ◽  
Initial Powder ◽  
Wide Range ◽  
Reduction Of Energy Consumption ◽  
Zn Alloy

Abstract Al and its alloys constitute one of the most versatile, economical and attractive materials for a wide range of applications. The 7xxx and 2xxx series alloys are those of achieving the highest mechanical strength among aluminum alloys. In this investigation, using powder metallurgy provides the microstructural and mechanical properties characterizations of non-commercial Al6Cu5Zn alloy by using powder metallurgy. Initial powder sizes are determined and the best condition is obtained for the distribution comprised between 75-106 μm. The samples are sintered at 585 oC, 600 oC and 615 oC during 0.5, 1.5 h and 3 h. It is found that mechanical behavior similar to as-cast Al-Cu based alloys is attained (~ 125 MPa) when the samples at 615 oC during 3 h are sintered. Considering the reduction of energy consumption and metal fumes commonly produced in foundry, Al-Zn powder can be used with Al and Cu elemental powders to constitute an Al6Cu5Zn alloy.

scholarly journals Mechanical Properties of 3C-SiC Films for MEMS Applications

2007 ◽  
Vol 1049 ◽  
Author(s):  
Jayadeep Deva Reddy ◽  
Alex A. Volinsky ◽  
Christopher L. Frewin ◽  
Chris Locke ◽  
Stephen E. Saddow
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Plastic Deformation ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Elastic Contact ◽  
Si Substrates ◽  
Sic Films

AbstractThere is a technological need for hard thin films with high elastic modulus and fracture toughness. Silicon carbide (SiC) fulfills such requirements for a variety of applications at high temperatures and for high-wear MEMS. A detailed study of the mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates was performed by means of nanoindentation using a Berkovich diamond tip. The thickness of both the single and polycrystalline SiC films was around 1-2 μm. Under indentation loads below 500 μN both films exhibit Hertzian elastic contact without plastic deformation. The polycrystalline SiC films have an elastic modulus of 457 GPa and hardness of 33.5 GPa, while the single crystalline SiC films elastic modulus and hardness were measured to be 433 GPa and 31.2 GPa, respectively. These results indicate that polycrystalline SiC thin films are more attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging.

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