Enhanced Instruction of Engineering Mechanics Using Curvature Experiments

2009 ◽  
Author(s):  
Byron L. Newberry
Keyword(s):  
Low Cost ◽  
Structural Response ◽  
Local Strain ◽  
Strain Gauges ◽  
Local Curvature ◽  
Post Process ◽  
Single Use ◽  
Strain Stress ◽  
Engineering Mechanics ◽  
Point Data

Resistive strain gauges are the most commonly used experimental devices for stress analysis. Their versatility stems from their ability to directly measure local strain on the surface of a structure, almost regardless of geometry. This strength can represent an educational limitation, however. Measurements made using strain gauges tend to provide results without students assessing or understanding the global structural response; limiting the insight gained and the instructional value of the experiment. Herein a low-cost device is presented that allows accurate measurement of local curvature in a beam. Once the local curvature is known, the elastic equations governing the beam may be used to calculate the local strain, stress, and deflection. The educational strength of the device is that students are forced to understand the interrelation of stress, strain, and deflection to post-process the experimental results. The device, though limited to beam geometries, has proven effective in helping students master engineering mechanics. It also allows investigation of the entire beam without added expense; as the device is not permanently affixed to one location. This is a significant advantage compared to strain gauges that provide only point data and are single-use. Details of the device itself, how it has been incorporated into the curriculum, and data assessing its effectiveness within a junior-level course are presented.

scholarly journals Microscale local strain gauges based on visible micro-disk lasers embedded in a flexible substrate

2018 ◽  
Vol 26 (13) ◽  
pp. 16797 ◽  
Author(s):  
Taojie Zhou ◽  
Jie Zhou ◽  
Yuzhou Cui ◽  
Xiu Liu ◽  
Jiagen Li ◽  
...  
Keyword(s):  
Flexible Substrate ◽  
Local Strain ◽  
Strain Gauges

Stiffened Hangers: an Often Overlooked Tool for Conceptual Design of Tied-Arch Footbridges

2021 ◽  
Author(s):  
Juan José Jorquera-Lucerga ◽  
Juan Manuel GARCÍA-GUERRERO
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Structural Response ◽  
Bending Moments ◽  
Structural Element ◽  
Axial Forces ◽  
Limited Effectiveness ◽  
Out Of Plane ◽  
Arch Bridges ◽  
Fixed End

<p>In tied-arch bridges, the way the arch and the deck are connected may become crucial. The deck is usually suspended from hangers made out of steel pinned cables capable of resisting axial forces only. However, a proper structural response, (both in-plane and out-of-plane) may be ensured by fixing and stiffening the hangers in order to resist, additionally, shear forces and bending moments. This paper studies the effect of different pinned and stiffened hanger arrangements on the structural behavior of the tied-arch footbridges, with the intention of providing designers with useful tools at the early steps of design. As a major conclusion, regarding the in-plane behavior, hangers composed of cables (either with vertical, Nielsen-Löhse or network arrangements) are recommended due to its low cost and ease of erection. Alternatively, longitudinally stiffened hangers, fixed at both ends, can be used. Regarding the out-of-plane behavior, and in addition to three-dimensional arrangements of cables, of limited effectiveness, transversally stiffened hangers fixed at both ends are the most efficient arrangement. A configuration almost as efficient can be achieved by locating a hinge at the end corresponding to the most flexible structural element (normally the arch). Its efficiency is further improved if the cross-section tapers from the fixed end to the pinned end.</p>

scholarly journals Performance of composite reinforced short column under axial loading

2018 ◽  
Vol 7 (3) ◽  
pp. 1376
Author(s):  
N Chaitanya ◽  
V Ranga Rao ◽  
M Achyutha Kumar Reddy
Keyword(s):  
Axial Loading ◽  
Element Model ◽  
Strain Gauges ◽  
Load Carrying Capacity ◽  
Short Column ◽  
Equal Angle ◽  
Short Columns ◽  
Load Carrying ◽  
Strain Stress ◽  
Loaded Column

The purpose of this paper is to compare the behaviour of composite reinforced concrete square short columns and conventional square short column. Experiments are conducted on four axially loaded column specimens till failure. Among four specimens, two are conventional and remaining two columns are having equal angles as main reinforcement. Short columns are designed using IS 456 2000. The obtained details of main reinforcement are replaced in area wise by equal angle (ISA 2525). The tie reinforcement used to withhold the main reinforcement in position are retained with the same deformed bars. Performance of columns are measured in terms of load carrying capacity, longitudinal strain, stress, crushing modes, strains in each face using strain gauges. Outcome of the experiments are compared and plotted in the form of stress vs strain of the column. A finite element model was developed using Abaqus to simulate the results.  

Reconstruction of Kyoto of the Edo era based on arts and historical documents: 3D urban model based on historical GIS data

2009 ◽  
Vol 3 (1-2) ◽  
pp. 21-38 ◽  
Author(s):  
Yuzuru Isoda ◽  
Akihiro Tsukamoto ◽  
Yoshihiro Kosaka ◽  
Takuya Okumura ◽  
Masakazu Sawai ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
3D Models ◽  
Historical Documents ◽  
Historical Gis ◽  
Model Based ◽  
Urban Model ◽  
Gis Data ◽  
Point Data

This paper explores a method for creating large-scale urban 3D models using Historical GIS data. The method is capable of automatically generating realistic VR models based on GIS data at a low cost. 3D models of houses are created from polygon data, fences from line data, and pedestrians and trees from point data. The method is applied to the Virtual Kyoto Project in which the landscape of the whole city of Kyoto of the early Edo era (ca 17C) is reconstructed.

A survey of inkjet-printed low-cost sensors

2018 ◽  
Vol 85 (7-8) ◽  
pp. 504-514
Author(s):  
Christoph Beisteiner ◽  
Bernhard G. Zagar
Keyword(s):  
Low Cost ◽  
Pressure Sensors ◽  
Strain Gauges ◽  
Temperature Dependent ◽  
Moulding Process ◽  
Seebeck Coefficients ◽  
Injection Moulding Process ◽  
Inkjet Printers ◽  
Lamination Process ◽  
Pet Films

Abstract Inkjet-printers from the company Epson and others can be used to fabricate low-cost sensors on coated PET films. By using nanoparticle-based dispersions resistive temperature dependent sensors, strain gauges, thermocouples and pressure sensors can be fabricated. For these purposes the gauge factors, Seebeck coefficients and temperature coefficients of resistance for Ag, Carbon Black and PEDOT:PSS dispersions on Mitsubishi® and Pelikan® PET substrates are characterized. Furthermore, piezoresistive effects in transverse and longitudinal strain directions are discussed. Additionally, a printed sensor system for measuring strains within a surface is presented. Finally, an injection-moulding process and a lamination process are used to improve the mechanical scratching of those sensors.

scholarly journals Application of Low-Cost Sensors for the Development of a Methodology to Design Front-End Loaders for Tractors

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
H. Malon ◽  
A. Ayuda ◽  
F. J. Garcia-Ramos ◽  
M. Vidal ◽  
J. Cuartero
Keyword(s):  
Finite Element Method ◽  
Low Cost ◽  
Strain Gauges ◽  
Second Phase ◽  
The Finite Element Method ◽  
Structural Behaviour ◽  
Experimental Phase ◽  
Front End ◽  
Accurate Design ◽  
Two Phases

Tractor front-end loaders are an essential part of the equipment used on farms. At present, there are an important number of small- and medium-sized companies involved in the manufacturing of this equipment. These companies rely heavily on experience for innovative designs, as in the vast majority of cases they lack access to adequate methodology for the optimal design of new front-end loaders. The study conducted has developed a methodology to design tractor front-end loaders with a view of obtaining their accurate design during the bucket loading process. The methodology comprises two phases: the first phase involves a numerical analysis of the structural behaviour of the front-end loader components by means of the Finite Element Method; the second phase, the experimental phase, makes use of low-cost sensors, in particular, strain gauges, to analyse existing strains at selected points in the front-end loader structure. The experimental results obtained by means of low-cost sensors fitted onto the front-end loader allow analysing the existing strains at the points measured, as well as validate the numerical model developed. This methodology is validated by applying it to a commercial front-end loader, more specifically to model 430E2 of the company Maquinaria Agrícola El León S.A (Spain).

scholarly journals Use of Particle Image Velocimetry (PIV) technique to measure strains in geogrids

2019 ◽  
Vol 92 ◽  
pp. 12007
Author(s):  
Chaminda Gallage ◽  
Chamara Jayalath
Keyword(s):  
Tensile Strength ◽  
Retaining Wall ◽  
Local Strain ◽  
Tensile Tests ◽  
Experimental Program ◽  
Strain Gauges ◽  
Data Logging ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Secant Stiffness

Geosynthetics are widely used in Geotechnical Engineering to reinforce soil/gravel in pavements, retaining wall backfills, and embankments. It is important to measure strains in geogrids in the determination of their strength parameters such as tensile strength and secant stiffness, and in evaluating their performances in geogrid-reinforced structures. Strain gauges are commonly used in measuring strains in geogrids. However, it is important to verify the strains measured by strain gauges as these strains are affected by the data logging device, gauge factors, quality of bonding between grain gauge and geogrid, and temperature. Therefore, this study was conducted to verify the performance of strain gauges attached to Geogrids and also to investigate the possibility of using PIV technique and GeoPIV-RG software to measure the local strains developed in a geogrid specimen under tensile testing in the laboratory. In the experimental program of this study, six composite geogrid specimens were tested for tensile strength (wide-width tensile tests) while measuring/calculating its tensile strain by using strain gauges attached to the specimens, Geo-PIV-RG analysis and crosshead movements of Instron apparatus. Good agreement between the strains obtained from strain gauges and geoPIV-RG analysis was observed for all the tests conducted. These results suggest that the PIV technique along with geoPIV-RG program can effectively be used to measure the local strain of geogrids in the laboratory tests. It was also able to verify that properly installed strain gauges are able to measure strain in the geogrids which are used in the field applications.

Differences between static and dynamic elastic moduli: Importance of experimental methods

2020 ◽  
Author(s):  
Elisabeth Bemer ◽  
Noalwenn Dubos-Sallée ◽  
Patrick N. J. Rasolofosaon
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Moduli ◽  
Young's Modulus ◽  
Local Strain ◽  
Experimental Methods ◽  
Triaxial Tests ◽  
Strain Gauges ◽  
Strain Measurements ◽  
Dynamic Elastic Moduli

&lt;p&gt;The differences between static and dynamic elastic moduli remain a controversial issue in rock physics. Various empirical correlations can be found in the literature. However, the experimental methods used to derive the static and dynamic elastic moduli differ and may entail substantial part of the discrepancies observed at the laboratory scale. The representativeness and bias of these methods should be fully assessed before applying big data analytics to the numerous datasets available in the literature.&lt;/p&gt;&lt;p&gt;We will illustrate, discuss and analyze the differences inherent to static and dynamic measurements through a series of triaxial and petroacoustic tests performed on an outcrop carbonate. The studied rock formation is Euville limestone, which is a crinoidal grainstone composed of roughly 99% calcite and coming from Meuse department located in Paris Basin. Sister plugs have been cored from the same quarry block and observed under CT-scanner to check their homogeneity levels.&lt;/p&gt;&lt;p&gt;The triaxial device is equipped with an internal stress sensor and provides axial strain measurements both from strain gauges glued to the samples and LVDTs placed inside the confinement chamber. Two measures of the static Young's modulus can thus be derived: the first one from the local strain measurements provided by the strain gauges and the second one from the semi-local strain measurements provided by the LVDTs. The P- and S-wave velocities are measured both through first break picking and the phase spectral ratio method, providing also two different measures of the dynamic Young's modulus.&lt;/p&gt;&lt;p&gt;The triaxial tests have been performed in drained conditions and the measured static elastic moduli correspond to drained elastic moduli. The petroacoustic tests have been performed using the fluid substitution method, which consists in measuring the acoustic velocities for various saturating fluids of different bulk modulus. No weakening or dispersion effects have been observed. Gassmann's equation can then be used to derive the dynamic drained elastic moduli and the solid matrix bulk modulus, which is otherwise either taken from the literature for pure calcite or dolomite samples, or computed using Voigt-Reuss-Hill or Hashin-Shtrikman averaging of the mineral constituents.&lt;/p&gt;&lt;p&gt;For the studied carbonate formation, we obtain similar values for static and dynamic elastic moduli when derived from careful lab experiments. Based on the obtained results, we will finally make recommendations, emphasizing the necessity of using relevant experimental techniques for a consistent characterization of the relation between static and dynamic elastic moduli.&lt;/p&gt;

scholarly journals Recreating mineralogical petrographic heterogeneity within microfluidic chips: assembly, examples, and applications

Lab on a Chip ◽  
2016 ◽  
Vol 16 (24) ◽  
pp. 4677-4681 ◽  
Author(s):  
Stephen A. Bowden ◽  
Yukie Tanino ◽  
Blessing Akamairo ◽  
Magali Christensen
Keyword(s):  
Low Cost ◽  
Microfluidic Chips ◽  
Single Use

We developed a technique for rapid, low-cost assembly of single-use, mineralogically heterogeneous microfluidic rock analogues.

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