scholarly journals Mechanical Response of Hollow Metallic Nanolattices: Combining Structural and Material Size Effects

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
L. C. Montemayor ◽  
J. R. Greer
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Relative Density ◽  
Size Effects ◽  
Scaling Laws ◽  
Tube Wall ◽  
Three Dimensional ◽  
Cellular Solids ◽  
Tube Wall Thickness ◽  
Strength And Stiffness

Ordered cellular solids have higher compressive yield strength and stiffness compared to stochastic foams. The mechanical properties of cellular solids depend on their relative density and follow structural scaling laws. These scaling laws assume the mechanical properties of the constituent materials, like modulus and yield strength, to be constant and dictate that equivalent-density cellular solids made from the same material should have identical mechanical properties. We present the fabrication and mechanical properties of three-dimensional hollow gold nanolattices whose compressive responses demonstrate that strength and stiffness vary as a function of geometry and tube wall thickness. All nanolattices had octahedron geometry, a constant relative density, ρ ∼ 5%, a unit cell size of 5–20 μm, and a constant grain size in the Au film of 25–50 nm. Structural effects were explored by increasing the unit cell angle from 30 deg to 60 deg while keeping all other parameters constant; material size effects were probed by varying the tube wall thickness, t, from 200 nm to 635 nm, at a constant relative density and grain size. In situ uniaxial compression experiments revealed an order of magnitude increase in yield stress and modulus in nanolattices with greater lattice angles, and a 150% increase in the yield strength without a concomitant change in modulus in thicker-walled nanolattices for fixed lattice angles. These results imply that independent control of structural and material size effects enables tunability of mechanical properties of three-dimensional architected metamaterials and highlight the importance of material, geometric, and microstructural effects in small-scale mechanics.

In-Plane Stiffness and Yield Strength of Periodic Metal Honeycombs

2004 ◽  
Vol 126 (2) ◽  
pp. 137-156 ◽  
Author(s):  
A.-J. Wang ◽  
D. L. McDowell
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Relative Density ◽  
Cell Types ◽  
Elastic Stiffness ◽  
Honeycomb Structures ◽  
Initial Yield ◽  
Cell Structures ◽  
Plane Anisotropy ◽  
Different Cell Types

In-plane mechanical properties of periodic honeycomb structures with seven different cell types are investigated in this paper. Emphasis is placed on honeycombs with relative density between 0.1 and 0.3, such that initial yield is associated with short column compression or bending, occurring prior to elastic buckling. Effective elastic stiffness and initial yield strength of these metal honeycombs under in-plane compression, shear, and diagonal compression (for cell structures that manifest in-plane anisotropy) are reported as functions of relative density. Comparison among different honeycomb structures demonstrates that the diamond cells, hexagonal periodic supercells composed of six equilateral triangles and the Kagome cells have superior in-plane mechanical properties among the set considered.

scholarly journals Extraction of mechanical properties of materials through deep learning from instrumented indentation

2020 ◽  
Vol 117 (13) ◽  
pp. 7052-7062 ◽  
Author(s):  
Lu Lu ◽  
Ming Dao ◽  
Punit Kumar ◽  
Upadrasta Ramamurty ◽  
George Em Karniadakis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Deep Learning ◽  
Scaling Laws ◽  
Three Dimensional ◽  
Instrumented Indentation ◽  
Multilayered Structures ◽  
Mechanical Properties Of Materials ◽  
Properties Of Materials ◽  
Indentation Problem ◽  
And Function

Instrumented indentation has been developed and widely utilized as one of the most versatile and practical means of extracting mechanical properties of materials. This method is particularly desirable for those applications where it is difficult to experimentally determine the mechanical properties using stress–strain data obtained from coupon specimens. Such applications include material processing and manufacturing of small and large engineering components and structures involving the following: three-dimensional (3D) printing, thin-film and multilayered structures, and integrated manufacturing of materials for coupled mechanical and functional properties. Here, we utilize the latest developments in neural networks, including a multifidelity approach whereby deep-learning algorithms are trained to extract elastoplastic properties of metals and alloys from instrumented indentation results using multiple datasets for desired levels of improved accuracy. We have established algorithms for solving inverse problems by recourse to single, dual, and multiple indentation and demonstrate that these algorithms significantly outperform traditional brute force computations and function-fitting methods. Moreover, we present several multifidelity approaches specifically for solving the inverse indentation problem which 1) significantly reduce the number of high-fidelity datasets required to achieve a given level of accuracy, 2) utilize known physical and scaling laws to improve training efficiency and accuracy, and 3) integrate simulation and experimental data for training disparate datasets to learn and minimize systematic errors. The predictive capabilities and advantages of these multifidelity methods have been assessed by direct comparisons with experimental results for indentation for different commercial alloys, including two wrought aluminum alloys and several 3D printed titanium alloys.

scholarly journals Effects of Simulation-Guided Microwave Presintering Process on the Preparation and Final Properties of Pure Ceramic Rings: Lower Sintering Temperature and Higher Mechanical Properties

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiao Lu ◽  
Tong-Tong Zhou ◽  
Feng-He Zhao ◽  
Xiao-Xiong Wang ◽  
Li-Xiang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electromagnetic Field ◽  
Relative Density ◽  
Textile Industry ◽  
Microwave Sintering ◽  
Three Dimensional ◽  
Simulation Software ◽  
Gel Casting ◽  
Average Grain Size ◽  
Conventional Sintering

In order to improve the performance and endurance of steel rings used for twisting and winding yarns in the textile industry, a more wear-resistant ceramic version is studied and examined by conducting multiple simulations combined with microwave sintering experiments of the ring preparation process, aiming to reduce manufacturing costs and improve efficiency. The three-dimensional (3D) electromagnetic field simulation software HFSS is used to simulate the electromagnetic field distribution in the microwave sintering cavity and to determine the electromagnetic region with the most uniform electromagnetic field to guide the microwave sintering experiments. The 3Y-TZP ceramic rings are shaped by gel-casting. The effect of presintering on the performance of ceramic rings is investigated by applying conventional sintering and microwave sintering methods. The experimental results show that the simulation-guided microwave sintering process can resolve the deficiency of uneven microwave sintering at low temperatures. Comparing the final sintering temperatures and mechanical properties of the final ceramic-sintered rings obtained by microwave presintering to those obtained by conventional presintering, microwave presintered sample has a final temperature of 1400°C, which is 100°C lower than that of conventional presintering, which is 1500°C; its average grain size of 0.18 μm is dramatically smaller than that of conventional presintering, which is 0.24 μm, with about 80% of the grain sizes present in the range of 0.1-0.2 μm and a relative density of about 99%, as opposed to conventional presintering’s 70% falling between 0.2 and 0.3 μm and relative density of about 98%; the Vickers hardness and fracture toughness for microwave presintered sample reach 1550 kg·f·mm−2 and 9.05 MPa m1/2, respectively, which are both greater than 1431 kg·f·mm−2 and 8.86 MPa m1/2 in the conventional samples.

The mechanics of three-dimensional cellular materials

1982 ◽  
Vol 382 (1782) ◽  
pp. 43-59 ◽  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Good Description ◽  
Large Body ◽  
Three Dimensional ◽  
Cellular Materials ◽  
Cellular Solids ◽  
Polymeric Foams ◽  
Cell Geometry

The mechanical properties (the moduli and collapse strengths) of three dimensional cellular solids or foams are related to the properties of the cell wall, and to the cell geometry. The results of the analyses give a good description of a large body of data for polymeric foams.

Experimental investigation on Iroko wood used in shipbuilding

2016 ◽  
Vol 231 (1) ◽  
pp. 128-139 ◽  
Author(s):  
V Bucci ◽  
P Corigliano ◽  
V Crupi ◽  
G Epasto ◽  
E Guglielmino ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strength Class ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Test Pieces ◽  
Hardwood Species ◽  
Glued Laminated Timber ◽  
Strength And Stiffness

The paper deals with investigations about mechanical properties of Iroko, a hardwood species used for structures in shipbuilding as glued laminated timber. Experimental tests have been carried out to assess strength, stiffness and density of Iroko in accordance with current EN Standards. All the results obtained by tensile and three-point bending tests, along with the statistical analyses performed to define the characteristics values of some mechanical properties, are reported in the paper. These values allowed to assign the strength class, reported in EN 338 Standard, to the investigated Iroko wood population. The experiments have taken into account both solid timber strips and scarf-jointed strips, in order to evaluate the influence of such a type of joint, which is widely used in wooden shipbuilding on strength and stiffness. Eventually, peculiar investigations have been carried out to analyse the failure mode of some test pieces through special experimental techniques: three-dimensional computed tomography and infrared thermography.

Effect of Tube Wall Thickness in Joining of Aluminum Tube and Holed Rib by Extrusion

2009 ◽  
Vol 424 ◽  
pp. 121-128
Author(s):  
T. Moroi ◽  
T. Kuboki ◽  
Makoto Murata
Keyword(s):  
Wall Thickness ◽  
Tube Wall ◽  
Metal Flow ◽  
Three Dimensional ◽  
Tube Wall Thickness ◽  
Die Surface ◽  
Elasto Plasticity ◽  
Two Parameters ◽  
Analysis Models ◽  
Extrude Tube

Existence of some holes at internal ribs enhances the function and value of the tubes. A new extrusion method is proposed here for the forming of this shape by extrusion with joining. The method involves the use of a unique mandrel that has a slit along its axis and two guides at the slit exit. A holed sheet is fed through the slit and joined with the inner surface of extrude tube. Effect of two parameters, that are tube-wall thickness and guide position h which is distance from guide top to die surface were clarified by FEA. Two kinds of three-dimensional analysis models were prepared. One of the analysis models treats the rib as rigid body to examine a gap between rib and tube. Another model treats the rib as the elasto-plasticity body as well as the billet to examine the effect of the guide position and the tube wall thickness on the rib deformation. The series of analyses was carried out with emphasis on the metal flow. The gap between tube and rib is able to be suppressed small and joining condition becomes satisfactory when guide position rose or tube wall was thin. When the guide position rose further, or the tube wall thickness was excessively thinner, the amount of the deformation of the rib increases, and it causes defects.

Microstructure and mechanical properties of three dimensional-printed continuous fiber composites

2018 ◽  
Vol 53 (2) ◽  
pp. 271-280 ◽  
Author(s):  
Cagri Oztan ◽  
Ryan Karkkainen ◽  
Mauro Fittipaldi ◽  
Garrett Nygren ◽  
Luke Roberson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Fiber Composites ◽  
Polymer Materials ◽  
Similar Process ◽  
Continuous Fiber ◽  
Fiber Volume ◽  
Multiple Length Scales ◽  
Strength And Stiffness ◽  
Future Work

Additive manufacturing processes have a demonstrated capacity for flexible production of metal and polymer components. More recently, capabilities for three dimensional printing of continuous fiber reinforced composites were developed. As with printed metal and polymer materials, printed composites will exhibit a unique microstructure with morphological features and process artifacts that manifest on multiple length scales. The aim of this research was to investigate the microstructures of various printed continuous fiber composites and determine linkages to consequent mechanical properties such as stiffness and strength. Samples investigated in this study comprised unidirectional carbon fibers in nylon matrix, unidirectional Kevlar fibers in nylon matrix, and Kevlar fibers in nylon matrix aligned at ±45° directions. Tensile properties of the samples were evaluated along with comparison to expected properties. Fiber volume ratios were analyzed by thermogravimetric analysis. Scanning electron microscopy and optical microscopy were used to observe and characterize the hierarchical microstructure. Both strength and stiffness were approximately 30–40% weaker than traditionally produced composites, owing to features such as imperfect interfaces between printed layers, microvoids, incomplete fill density, and similar process artefacts. Future work will investigate mitigation of such effects through process modifications and post-processing to produce higher performance printed composites.

Effect of Magnesium on the Strength, Stiffness and Toughness of Nodular Cast Iron

2020 ◽  
Vol 991 ◽  
pp. 17-23
Author(s):  
Agung Setyo Darmawan ◽  
Pramuko Ilmu Purboputro ◽  
Agus Yulianto ◽  
Agus Dwi Anggono ◽  
Wijianto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Yield Strength ◽  
Tensile Test ◽  
Impact Test ◽  
Nodular Cast Iron ◽  
Ferrite Matrix ◽  
Strength And Stiffness ◽  
The Impact

Nodular cast iron is a type of cast iron with spheroid graphite surrounded by ferrite matrix and / or pearlite. The size of the graphite and its matrix affects the mechanical properties of the cast iron. This research was conducted to investigate the effect of Magnesium composition on strength, stiffness and toughness of nodular cast iron. Magnesium addition is performed by adding FeSiMg alloys. After that, the composition of magnesium was investigated by using spectrometry. Then tensile test was conducted to obtain the yield strength, tensile strength and modulus of elasticity. Further, impact test was performed to determine the impact energy needed to break the material. The result showed an increase of yield strength, tensile strength and stiffness and a decrease of toughness.

scholarly journals The Size Effects of Point Defect on the Mechanical Properties of Monocrystalline Silicon: A Molecular Dynamics Study

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3011
Author(s):  
Wei Wan ◽  
Changxin Tang ◽  
An Qiu ◽  
Yongkang Xiang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Yield Strength ◽  
Point Defect ◽  
Size Effects ◽  
Constant Strain Rate ◽  
Monocrystalline Silicon ◽  
Dislocation Slip ◽  
Actual Strength ◽  
Yield Strength Variation

The molecular dynamics method was used to simulate the fracture process of monocrystalline silicon with different sizes of point defect under a constant strain rate. The mechanism of the defect size on the mechanical properties of monocrystalline silicon was also investigated. The results suggested that the point defect significantly reduces the yield strength of monocrystalline silicon. The relationships between the yield strength variation and the size of point defect fitted an exponential function. By statistically analyzing the internal stress in monocrystalline silicon, it was found that the stress concentration induced by the point defect led to the decrease in the yield strength. A comparison between the theoretical strength given by the four theories of strength and actual strength proved that the Mises theory was the best theory of strength to describe the yield strength of monocrystalline silicon. The dynamic evolution process of Mises stress and dislocation showed that the fracture was caused by the concentration effect of Mises stress and dislocation slip. Finally, the fractured microstructures were similar to a kind of two-dimensional grid which distributed along the cleavage planes while visualizing the specimens. The results of this article provide a reference for evaluating the size effects of point defects on the mechanical properties of monocrystalline silicon.

scholarly journals Mechanical Properties of Dental Alloys According to Manufacturing Process

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3367
Author(s):  
Ji-Min Yu ◽  
Seen-Young Kang ◽  
Jun-Seok Lee ◽  
Ho-Sang Jeong ◽  
Seung-Youl Lee
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Yield Strength ◽  
Modulus Of Elasticity ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Dental Alloys ◽  
Cad Cam ◽  
Scheffe Method ◽  
Printing Method

The purpose of this study is to investigate the effect of the fabrication method of dental prosthesis on the mechanical properties. Casting was produced using the lost wax casting method, and milling was designed using a CAD/CAM program. The 3D printing method used the SLS technique to create a three-dimensional structure by sintering metal powder with a laser. When making the specimen, the specimen was oriented at 0, 30, 60, and 90 degrees. All test specimens complied with the requirements of the international standard ISO 22674 for dental alloys. Tensile strength was measured for yield strength, modulus of elasticity and elongation by applying a load until fracture of the specimen at a crosshead speed of 1.5 ± 0.5 mm/min (n = 6, modulus of elasticity n = 3). After the tensile test, the cross section of the fractured specimen was observed with a scanning electron microscope, and the statistics of the data were analyzed with a statistical program SPSS (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY, USA: IBM Corp.) and using Anova and multiple comparison post-tests (scheffe method). The yield strength was the highest at 1042 MPa at an angle of 0 degrees in the specimen produced by 3D printing method, and the elongation was the highest at 14% at an angle of 90 degrees in the specimen produced by 3D printing method. The modulus of elasticity was the highest at 235 GPa in the milled specimen. In particular, the 3D printing group showed a difference in yield strength and elongation according to the build direction. The introduction of various advanced technologies and digital equipment is expected to bring high prospects for the growth of the dental market.

Sign in / Sign up

Export Citation Format

Share Document