On non-circularity of tree stem cross-sections: effect of diameter selection on cross-section area estimation, Bitterlich sampling and stem volume estimation in Scots pine

In this experimental work, strength results obtained on short columns subjected to concentric loads are presented. The specimens used in the tests have made of cold-rolled, thin-walled steel. Twenty short columns of the same cross-section area and wall thickness have been tested as follows: 8 empty and 12 filled with ordinary concrete. In the aim to determine the column section geometry with the highest resistance, three different types of cross-sections have been compared: rectangular, I-shaped unreinforced and, reinforced with 100 mm spaced transversal links. The parameters studied are the specimen height and the cross-sectional steel geometry. The registered experimental results have been compared to the ultimate loads intended by Eurocode 3 for empty columns and by Eurocode 4 for compound columns. These results showed that a concrete-filled composite column had improved strength compared to the empty case. Among the three cross-section types, it has been found that I-section reinforced is the most resistant than the other two sections. Moreover, the load capacity and mode of failure have been influenced by the height of the column. Also, it had noted that the experimental strengths of the tested columns don’t agree well with the EC3 and EC4 results.

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Exact Longitudinal Vibration Characteristics of Rods with Variable Cross-Sections

Shock and Vibration ◽

10.1155/2011/574690 ◽

2011 ◽

Vol 18 (4) ◽

pp. 555-562 ◽

Cited By ~ 8

Author(s):

Bulent Yardimoglu ◽

Levent Aydin

Keyword(s):

Differential Equation ◽

Cross Section ◽

Cross Sections ◽

Longitudinal Vibration ◽

Transformation Method ◽

Variable Cross ◽

Cross Sectional ◽

Cross Section Area ◽

Section Area ◽

Sinusoidal Functions

Longitudinal natural vibration frequencies of rods (or bars) with variable cross-sections are obtained from the exact solutions of differential equation of motion based on transformation method. For the rods having cross-section variations as power of the sinusoidal functions ofax+b, the differential equation is reduced to associated Legendre equation by using the appropriate transformations. Frequency equations of rods with certain cross-section area variations are found from the general solution of this equation for different boundary conditions. The present solutions are benchmarked by the solutions available in the literature for the special case of present cross-sectional variations. Moreover, the effects of cross-sectional area variations of rods on natural characteristics are studied with numerical examples.

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AN EXPERIMENTAL INVESTIGATION OF SOIL LAYER COUPLING FAILURE CHARACTERISTICS ON NATURAL GRASSLAND BY PASSIVE SUBSOILER-TYPE OPENERS

INMATEH Agricultural Engineering ◽

10.35633/inmateh-61-06 ◽

2020 ◽

pp. 49-58 ◽

Cited By ~ 1

Author(s):

Changbin He ◽

Yong You ◽

Decheng Wang ◽

Hongjian Wu ◽

Bingnan Ye

Keyword(s):

Cross Section ◽

Cross Sections ◽

Layer Structure ◽

Soil Layer ◽

Failure Characteristics ◽

Design And Optimization ◽

Cross Section Area ◽

Section Area ◽

Draft Force ◽

Natural Grassland

Unclear soil layer coupling failure characteristics on natural grassland impeded the design and optimization of appropriate tillage tools. The coupling failure characteristics including surface disturbance and profile, disturbed cross-section area, soil over-turning rate, and coupling forces between the soil layer of natural grassland and selected passive subsoiler-type openers were investigated in this paper. Three single-shoot openers (i.e. CO, AO and WAO) and a test unit were designed, and furrow opening experiments under different working depths were conducted. Results showed that, along the passages, U-shaped disturbed cross-sections were usually created with soil-root clods overturned along the furrows. The roots were usually broken in a pulling or dragging way underground. Both disturbed cross-section area and draft force values increased with the working depth increasing linearly (R2≥0.93), contrary to the tendency of the specific draft force with the depth. Winged opener (i.e. WAO) had larger draft forces and disturbed soil layer cross-section areas than no-winged openers (i.e. AO and CO). The soil layer failure processes of the natural grassland were affected by its composite soil layer structure and the geometry parameters of the openers. The results provide original references for designing novel furrow openers applicable to improve degraded natural grassland.

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A unified procedure for the vibration analysis of elastically restrained Timoshenko beams with variable cross sections

Noise Control Engineering Journal ◽

10.3397/1/37683 ◽

2020 ◽

Vol 68 (1) ◽

pp. 38-47

Author(s):

Gang Wang ◽

Wen L. Li ◽

Wanyou Li ◽

Zhihua Feng ◽

Junfang Ni

Keyword(s):

Cross Section ◽

Cross Sections ◽

Vibration Analysis ◽

Variable Cross Section ◽

Variable Cross ◽

Timoshenko Beams ◽

Unified Approach ◽

Cross Section Area ◽

Section Area ◽

Elastically Restrained

A generalized analytical method is developed for the vibration analysis of Timoshenko beams with elastically restrained ends. For a beam with any variable cross section along the lengthwise direction, the finite element method is the only unified approach to handle those kinds of problems, since the analytical solutions could not be obtained by the governing equations when the cross section area and the second moment of area changing variably lengthwise. In this article, a unified approach is proposed to study the Timoshenko beam with any variable cross sections. The cross section area and second moment of area of the beam are both expanded into cosine series, which are mathematically capable of representing any variable cross section. The translational displacement and rotation of cross section are expressed in the Fourier series by adding some admissible functions which are used to handle the elastic boundary conditions with more accuracy and high convergence rate. By using Hamilton's principle, the eigenvalues and the coefficients of the Fourier series are both obtained. Some examples are presented to illustrate the excellent accuracy of this method. Analytical solutions of the vibration of the beam are achieved for different combinations of boundary conditions including classical and elastically restrained ones. The derived results can be used as benchmark solutions for testing approximate or numerical methods used for the vibration analysis of Timoshenko beams with any variable cross section.

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Tests of Concrete Strength across the Thickness of Industrial Floor Using the Ultrasonic Method with Exponential Spot Heads

Materials ◽

10.3390/ma13092118 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2118 ◽

Cited By ~ 6

Author(s):

Bohdan Stawiski ◽

Tomasz Kania

Keyword(s):

Compressive Strength ◽

Cross Section ◽

Cross Sections ◽

Ultrasonic Method ◽

Concrete Strength ◽

Testing Machine ◽

Cross Section Area ◽

Section Area ◽

Strength Result

The accepted methods for testing concrete are not favorable for determining its heterogeneity. The interpretation of the compressive strength result as a product of destructive force and cross-section area is burdened with significant understatements. It is assumed erroneously that this is the lowest value of strength at the height of the tested sample. The top layer of concrete floors often crumble, and the strength tested using sclerometric methods does not confirm the concrete class determined using control samples. That is why it is important to test the distribution of compressive strength in a cross-section of concrete industrial floors with special attention to surface top layers. In this study, we present strength tests of borehole material taken from industrial floors using the ultrasonic method with exponential spot heads with a contact surface area of 0.8 mm2 and a frequency of 40 kHz. The presented research project anticipated the determination of strength for samples in various cross-sections at the height of elements and destructive strength in the strength testing machine. It was confirmed that for standard and big borehole samples, it is not possible to test the strength of concrete in the top layer of the floor by destructive methods. This can be done using the ultrasonic method. After the analysis, certain types of distributions of strength across concrete floor thickness were chosen from the completed research program. The gradient and anti-gradient of strength were proposed as the new parameters for the evaluation of floor concrete quality.

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Thermoelectricity in periodic and quasiperiodically segmented nanobelts and nanowires

MRS Advances ◽

10.1557/adv.2016.291 ◽

2016 ◽

Vol 1 (60) ◽

pp. 3953-3958 ◽

Cited By ~ 2

Author(s):

J. Eduardo Gonzalez ◽

Vicenta Sanchez ◽

Chumin Wang

Keyword(s):

Cross Section ◽

Cross Sections ◽

Figure Of Merit ◽

Tight Binding ◽

Fibonacci Sequence ◽

Real Space ◽

Thermoelectric Figure ◽

Cross Section Area ◽

Section Area ◽

Convolution Method

ABSTRACTThermoelectric properties of segmented nanowires and nanobelts are studied by means of the Kubo-Greenwood formula and a real-space renormalization plus convolution method. The tight-binding and Born models are respectively used for the calculation of electronic and lattice thermal conductivities. In particular, we investigate the thermoelectric figure of merit (ZT) of periodic and quasiperiodically segmented nanowires with two different cross sections, where the segments of the quasiperiodic one are ordered following the Fibonacci sequence. The results show an increase of ZT when the cross section area of nanowires diminishes. In addition, we present results of ZT in segmented nanobelts with an inhomogeneous cross section. For both nanowires and nanobelts, the quasiperiodicity seems to be an important enhancing factor of ZT.

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Design Improvement of Y-TZP Three Unit Bridges by Predicted Stress Concentration Using FEA and Experimental Failure Modes after Three Point Bending Test

Revista de Chimie ◽

10.37358/rc.19.1.6912 ◽

2019 ◽

Vol 70 (1) ◽

pp. 336-342

Author(s):

Adrian Almasi ◽

Iulian Antoniac ◽

Sergiu Focsaneanu ◽

Marius Manole ◽

Robert Ciocoiu ◽

...

Keyword(s):

Cross Section ◽

Cross Sections ◽

Failure Modes ◽

Bending Test ◽

Design Improvement ◽

Cross Section Area ◽

Section Area ◽

Starting Point ◽

Cad Cam ◽

Experimental Trials

In this study an attempt to improve a three unit partial denture design is presented by performing experimental trials to find the failure load of a Y-TZP dental infrastructure. The experimental results are linked with FEA predictions to explain failure and find the optimum design. The test samples used were three unit fixed partial dentures obtained by CAD/CAM using as starting point a clinical case. Design improvement attempt was to increase connector cross-section size and modify its shape. Four samples with circular and elliptical connector cross-sections and 5mm2 and 9mm2 area were tested in flexure. The models created for CAM were used to perform FEA and find the stress distribution, pinpoint the stress concentrators and link the results to experimental failure modes. The results showed that connector design plays an important role in restoration success and increasing connector cross-section area the stress is distributed in a uniform manner. It was concluded that increasing connector cross-section area and using a wider shape (ellipse) strongly decreases failure probability.

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