A Micromechanical Bending Stage for Studying Mechanical Properties of Materials Using Nanoindenter

2015 ◽  
Vol 82 (12) ◽  
Author(s):  
Mohamed Elhebeary ◽  
M. Taher A. Saif
Keyword(s):  
Analytical Model ◽  
Small Volume ◽  
Bending Test ◽  
Bending Stress ◽  
Entire Volume ◽  
Premature Failure ◽  
State Of Stress ◽  
3D Printed ◽  
Properties Of Materials ◽  
Good Agreement

An analytical and computational model of a novel bending stage is presented. The stage applies bending moments on micro/nanoscale beam specimens using a nanoindenter. In uniaxial tests, any flaw within the entire volume of the specimen may lead to fracture before material yields. The new stage minimizes the volume of material under a uniaxial state of stress in the specimen, but maximizes bending stress over a small volume such that high stresses can be reached within a small volume on the specimen without a premature failure by fracture. The analytical model of the stage accounts for the geometric nonlinearity of the sample, but assumes simplified boundary conditions. It predicts the deflection and stresses in the specimen beam upon loading. The numerical model of the stage and the specimen employing a finite element (FE) package tests the validity of the analytical model. Good agreement between analytical and numerical results shows that the assumptions in the analytical model are reasonable. Therefore, the analytical model can be used to optimize the design of the stage and the specimen. A design of the stage is presented that results in axial/bending stress < 2% in the sample. In order to test the feasibility of the proposed design, a 3D printed stage and a sample are fabricated using the Polyamide PA2200. Bending test is then carried out employing an indenter. Elastic modulus of PA2200 is extracted from the load-deflection data. The value matches closely with that reported in the literature.

Monotonic and fatigue assessment of steel-concrete composite beams strengthened with externally post-tensioned tendons

2018 ◽  
Author(s):  
◽  
Ayman Elzohairy
Keyword(s):  
Numerical Model ◽  
Composite Beam ◽  
Composite Beams ◽  
Fatigue Tests ◽  
Flexural Behavior ◽  
Bending Test ◽  
Steel Beam ◽  
Premature Failure ◽  
Post Tensioning ◽  
Post Tensioned

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The steel-concrete composite beam represents a structural system widely employed in both buildings and girder bridges. The coupling between steel beams and concrete flanges assures both economic and structural benefits because of quick construction of steel structures and large increase in stiffness due to the presence of concrete. Strengthening with external post-tensioning (PT) force is particularly effective and economical for long-span steel-concrete composite beams and has been employed with great success to increase the bending and shear resistance and correct excessive deflections. Applying external PT force to the steel-concrete composite beam is considered an active strengthening technique that can create permanent internal straining action in the beam which is opposite to the existing straining action due to the applied service loads. The most benefits of using this system of strengthening are an elastic performance to higher loads, higher ultimate capacity, and reduction in deformation under the applied loads. Under service loads, bridge superstructures are subjected to cyclic loads which may cause a premature failure due to fatigue. Therefore, fatigue testing is critical to evaluate existing design methods of steel-concrete composite beams. ... This research presents static and fatigue tests on four steel-concrete composite specimens to evaluate the effect of externally post-tensioned tendons on the ultimate strength and fatigue behavior of composite beams. Fatigue tests are conducted to a million cycles under a four-point bending test. In addition, final static tests are performed on fatigued specimens to evaluate the residual strength of the strengthened specimen. A numerical model is described to predict the fatigue response of the composite beam by considering the fatigue damage in the concrete flange. The accuracy of the developed numerical model is validated using the existing test data. The static test results indicate that the external post-tensioning force improves the flexural behavior of the strengthened specimen by increasing the beam capacity and reducing the tensile stress in the bottom flange of the steel beam. The fatigue results demonstrate that the external post-tensioning significantly decreases the strains in the shear connectors, concrete flange, and steel beam. The tendons demonstrated an excellent fatigue performance, with no indication of distress at the anchors.

scholarly journals Off-Axis Diffractive Optics for Compact Terahertz Detection Setup

2020 ◽  
Vol 10 (23) ◽  
pp. 8594
Author(s):  
Paweł Komorowski ◽  
Mateusz Surma ◽  
Michał Walczakowski ◽  
Przemysław Zagrajek ◽  
Agnieszka Siemion
Keyword(s):  
3D Printing ◽  
Small Volume ◽  
Optical Element ◽  
Structure Design ◽  
Thz Radiation ◽  
Direct Printing ◽  
Terahertz Detection ◽  
3D Printed ◽  
Printing Techniques ◽  
Optical Structure

Medical and many other applications require small-volume setups enabling terahertz imaging. Therefore, we aim to develop a device for the in-reflection examination of the samples. Thus, in this article, we focus on the diffractive elements for efficient redirection and focusing of the THz radiation. A terahertz diffractive optical structure has been designed, optimized, manufactured (using extrusion-based 3D printing) and tested. Two manufacturing methods have been used—direct printing of the structures from PA12, and casting of the paraffin structures out of 3D-printed molds. Also, the limitations of the off-axis focusing have been discussed. To increase the efficiency, an iterative algorithm has been proposed that optimizes off-axis structures to focus the radiation into small focal spots located far from the optical axis, at an angle of more than 30 degrees. Moreover, the application of higher-order kinoform structure design allowed the maintaining of the smallest details of the manufactured optical element, using 3D printing techniques.

The 3D-printed socket could not tolerate the bending test, resulting in snapping before being completely straightened (point of failure)

ASVIDE ◽  
2018 ◽  
Vol 5 ◽  
pp. 429-429
Author(s):  
Teruya Komatsu ◽  
Toshihiko Sato ◽  
Yasuto Sakaguchi ◽  
Yusuke Muranishi ◽  
Yojiro Yutaka ◽  
...  
Keyword(s):  
Bending Test ◽  
3D Printed

Design and Fabrication of 3D Printed Reconfigurable Metamaterial-inspired Structures

2019 ◽  
Vol 2019 (1) ◽  
pp. 000595-000598
Author(s):  
Saranraj Karuppuswami ◽  
Avi Rajendra-Nicolucci ◽  
Saikat Mondal ◽  
Mohd Ifwat Mohd Ghazali ◽  
Premjeet Chahal
Keyword(s):  
High Temperature ◽  
Small Volume ◽  
Ring Resonator ◽  
Low Cost ◽  
Microfluidic Channel ◽  
Split Ring Resonator ◽  
Split Ring ◽  
Liquid Samples ◽  
Volatile Organic ◽  
3D Printed

Abstract In this paper, 3D printing is used as an alternative manufacturing technique to fabricate metamaterial-inspired RF structures for liquid profiling. A dual split-ring resonator (SRR) based sensor tag is designed and integrated with a microfluidic channel for detecting different liquid samples. The sensor is 3D printed using a high-temperature resin and metallized using a custom developed metal patterning process. The sensor requires a very small volume of 8.6 μL of sample under test for detection. The resonance frequency of the SRR changes with change in sample loading and the shift is monitored for sample profiling. Different volatile organic compounds are introduced and the shift is monitored demonstrating the sensitivity of the proposed tag. The low-cost, real-time nature of the tag makes it an ideal choice for monitoring liquids along the supply chain.

scholarly journals Evaluation of Low Temperature Cracking of Asphalt Mixture Modified with PPA Using Acoustic Emission Technique

2018 ◽  
Vol 7 (4.20) ◽  
pp. 541
Author(s):  
Mojtaba Kodadadi ◽  
Ali Khodaii
Keyword(s):  
Acoustic Emission ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Limestone Aggregate ◽  
Failure Energy ◽  
Low Temperature Cracking ◽  
Spss Software ◽  
Non Destructive ◽  
Good Agreement

In this study, the behavior of asphalt mixture was studied using non-destructive Acoustic Emission (AE) technique at low temperatures. For this purpose, two types of bitumen 60/70 and 85/100 with two types of limestone and Silica aggregate were used to construct asphalt mixtures. Polyphosphoric acid (PPA) was used to modify the bitumen in the dosage of 0, 0.5, 1.0 and 1.5% of bitumen weight. Semicircular bending test (SCB) under a steady increasing strain at a rate of 3mm/min was conducted at 0, -10-, and -20 °C. Two AE channels were used to record the Sinusoid output around the crack of SCB sample during crack growth. Analysis of the results obtained from this study using SPSS software indicates that there is a significant relationship between the failure energy of SCB samples and the number of impacts received from AEs. Furthermore, AE energy has a good agreement with the sample failure energy. According to the failure criterion, asphalt mixtures containing 85/100 bitumen modified by 1.0% of PPA and limestone aggregate exhibit more crack resistance among other compositions.  

Analytical solution for twinning deformation effect of pre-strained shape memory effect beam-columns

2019 ◽  
Vol 30 (14) ◽  
pp. 2147-2165 ◽  
Author(s):  
Alireza Ostadrahimi ◽  
Fathollah Taheri-Behrooz
Keyword(s):  
Shape Memory Alloy ◽  
Analytical Solution ◽  
Shape Memory ◽  
Cross Sections ◽  
Bending Stress ◽  
Deformation Effect ◽  
One Dimensional ◽  
Beam Columns ◽  
Analytical Expressions ◽  
Good Agreement

In this article, an analytical solution is presented for twinning deformation effect of a prismatic shape memory alloy beam-column. To this end, a reduced one-dimensional Souza model is employed to study the bending stress of a pre-strained shape memory alloy beam-column at low temperatures. Analytical expressions for bending stress as well as polynomial approximations for deflection are obtained. Derived equations for bending problem are employed to analyze twinning deformation effect of shape memory alloy beam-columns with rectangular and circular cross sections. Furthermore, the distance of zero-stress fiber from the center line during loading is studied. The results of this work show good agreement when compared with experimental data and finite element results.

scholarly journals Open-source, 3D-printed Peristaltic Pumps for Small Volume Point-of-Care Liquid Handling

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Michael R. Behrens ◽  
Haley C. Fuller ◽  
Emily R. Swist ◽  
Jingwen Wu ◽  
Md. Mydul Islam ◽  
...  
Keyword(s):  
Open Source ◽  
Small Volume ◽  
Point Of Care ◽  
Liquid Handling ◽  
Peristaltic Pumps ◽  
3D Printed

Secondary Fluorescence of 3D Heterogeneous Materials Using a Hybrid Model

2020 ◽  
Vol 26 (3) ◽  
pp. 484-496
Author(s):  
Yu Yuan ◽  
Hendrix Demers ◽  
Xianglong Wang ◽  
Raynald Gauvin
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Analytical Model ◽  
Hybrid Model ◽  
Three Dimensional ◽  
Heterogeneous Materials ◽  
X Ray ◽  
The Monte Carlo Method ◽  
Secondary Fluorescence ◽  
Good Agreement

AbstractIn electron probe microanalysis or scanning electron microscopy, the Monte Carlo method is widely used for modeling electron transport within specimens and calculating X-ray spectra. For an accurate simulation, the calculation of secondary fluorescence (SF) is necessary, especially for samples with complex geometries. In this study, we developed a program, using a hybrid model that combines the Monte Carlo simulation with an analytical model, to perform SF correction for three-dimensional (3D) heterogeneous materials. The Monte Carlo simulation is performed using MC X-ray, a Monte Carlo program, to obtain the 3D primary X-ray distribution, which becomes the input of the analytical model. The voxel-based calculation of MC X-ray enables the model to be applicable to arbitrary samples. We demonstrate the derivation of the analytical model in detail and present the 3D X-ray distributions for both primary and secondary fluorescence to illustrate the capability of our program. Examples for non-diffusion couples and spherical inclusions inside matrices are shown. The results of our program are compared with experimental data from references and with results from other Monte Carlo codes. They are found to be in good agreement.

scholarly journals Response of a Warped Flexible Rotor with a Fluid Bearing

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Jim Meagher ◽  
Xi Wu ◽  
Chris Lencioni
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Equation Of Motion ◽  
Diagnostic Information ◽  
Flexible Rotor ◽  
Vibration Data ◽  
Rotor Model ◽  
Good Agreement

A two-complex-degrees-of-freedom model is developed and compared to experimental data for various amounts of rotor bow and its orientation to mass imbalance of the rotor. The equation of motion is developed by adding constant forces that rotate with the rotor to a Bently-Muszynska two-mode isotropic rotor model with a plane journal bearing. Diagnostic information discernable from probes at the bearing is explored and compared to midspan response, where previous research has concentrated. The model presented also extends earlier work by representing the effect of a nonrigid bearing. Good agreement between the analytical model and experiment demonstrates that the analysis presented can be useful to diagnose and balance residual shaft bow from probes located at the bearings, where vibration data are typically more available than midspan probes.

A Semi-Analytical Model for Buckling of Laminated Plates with the NKQ Method

2012 ◽  
Vol 232 ◽  
pp. 68-72
Author(s):  
Rasoul Khandan ◽  
Siamak Noroozi ◽  
John Vinney ◽  
Philip Sewell ◽  
Mehran Koohgilani
Keyword(s):  
Analytical Model ◽  
Linear Equations ◽  
Laminated Plates ◽  
General Distribution ◽  
General Boundary Conditions ◽  
Kantorovich Method ◽  
Linear Integral ◽  
Non Linear Equations ◽  
Linear Integral Equations ◽  
Good Agreement

A semi-analytical approach for analysis of laminated plates with general boundary conditions under a general distribution of loads is developed. The non-linear equations are solved by the Newton-Kantorovich-Quadrature (NKQ) method which is a combination of well-known Newton-Kantorovich method and the Quadrature method. This method attempts to solve a sequence of linear integral equations. In this paper this method is used to propose a semi-analytical model for buckling of laminated plates. The convergence of the proposed method is investigated and the validation of the method is explored through numerical examples and the results compared with finite element method (FEM). There is a good agreement between the NKQ model and FEM results.

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