A Mechanical Oscillograph for Routine Tests of Rubber and Rubber-Like Materials

1940 ◽  
Vol 13 (1) ◽  
pp. 149-158 ◽  
Author(s):  
Felix L. Yerzley
Keyword(s):  
Test Specimen ◽  
Mechanical Characteristics ◽  
Load Capacity ◽  
Standard Test ◽  
Laboratory Instrument ◽  
Early State ◽  
Compression Data

Abstract The oscillograph described has been developed primarily as a laboratory instrument to evaluate rubber and Neoprene compounds for mechanical applications. It is complete in itself as a means of measuring all of the quantities inherently involved in such service in units which are understandable to rubber technologists and mechanical engineers alike. It is hoped that it may serve its purpose by bringing into closer cooperation those who make and those who use rubber springs. The details of the test have been carefully developed, and it is expected that the machine and standard test-specimen described will not need essential modification for routine use. However, enough background has been given so that the machine may be modified in accordance with definite principles in order to gain greater load capacity if required. The test has been restricted thus far to compression. The author expects to adapt the machine to tests in shear, and by correlation between shear data and compression data to obtain figures capable of substitution in relationships already offered by other investigators for calculations in the applications and design of rubber springs. This field of calculation is complicated and in an early state of development, but by the use of the oscillograph it should be easier to obtain the quantities of information required to clarify our understanding of the mechanical characteristics of rubber-like materials within the range of deformation encountered in structural use.

scholarly journals Physico-mechanical Characteristics of High Density Briquettes produced from Composite Sawdust

2020 ◽  
Vol 24 (5) ◽  
pp. 779-787 ◽  
Author(s):  
R.S. Bello ◽  
M.A. Onilude
Keyword(s):  
Dimensional Stability ◽  
Mechanical Characteristics ◽  
Impact Resistance ◽  
Resistance Index ◽  
Standard Test ◽  
Physical Characteristics ◽  
Particle Sizes ◽  
Empirical Relationships ◽  
Independent Variables ◽  
Production Effects

Physico-mechanical characteristics of briquettes produced from composite sawdust admixture using a screw press briquetting machine was investigated. Sample feedstock materials collected has particle sizes varying between 6-8mm with 10-20% powdery components (< 4 mesh). Briquette’s physical characteristics investigated using standard test apparatus and procedures include dimensional stability immediately, 1 hour and 30 days after production, effects of particle moisture and particle size on briquette compressed and relaxed densities. Mechanical characteristics include resistance to gravity and impact, effects of densities on impact resistance index (IRI) and effects of briquette durability in water. Statistical models were used to establish empirical relationships between the feedstock materials (independent variables) and briquette characteristics (independent variables). The physical characteristics of briquettes produced at 12% are loose and brittle with poor dimensional stability, at 10% they are bonded but weak in strength with good dimensional stability while briquettes produced at 8% are wellformed, good colouration with char carbonation, excellent dimensional stability. The compressed density of the briquettes ranges of 490-820 kg/m3. The lower moisture briquettes have high resistance to water dispersion, high impact resistance and excellent storability. Keywords: Characterization, extrusion, briquette, sawmill, sawdust

The edge-cracked circular disc under symmetric pin-loading

1979 ◽  
Vol 85 (3) ◽  
pp. 523-538 ◽  
Author(s):  
R. D. Gregory
Keyword(s):  
Stress Intensity ◽  
Stress Field ◽  
Test Specimen ◽  
Edge Crack ◽  
Standard Test ◽  
Circular Disc ◽  
Crack Mouth ◽  
Intensity Factors ◽  
Point Forces ◽  
Image Position

A circular disc of radius a, made of homogeneous, isotropic, linearly elastic material, contains a radial edge crack of length b(0 < b < 2a). The disc is in equilibrium in a state of generalized plane stress under various loadings, which are motivated by the fact that this geometry is to become a standard test specimen configuration in the fracture testing of materials.The first cases considered are those in which the disc is loaded by either (i) opposing point forces P normal to the crack, or (ii) opposing point couples M, in each case acting at the crack mouth. The problem of determining the resulting stress field throughout the disc is solved analytically in closed form in each case, and the respective stress intensity factors are given exactly bywhere K+(0), K+(i) are constants whose values areK+(0) = 0.966528…,K+(i) = 0.355715…,correct to 6 decimal places.

scholarly journals An approximate solution of compact test specimen for mode I fracture test by variational approach: Applied to fibrous composite

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 7223-7233
Author(s):  
Yuling Bian ◽  
Baolu Sheng ◽  
Aiping Zhou
Keyword(s):  
Approximate Solution ◽  
Test Specimen ◽  
Fibrous Composite ◽  
Initial Crack ◽  
Standard Test ◽  
Fe Model ◽  
Fracture Test ◽  
Initial Crack Length ◽  
Calculation Results ◽  
Compact Test

The present work presented an approximate solution for a compact test (CT) specimen that was employed as a standard test provided by ASTM E399-19 (2019). The variational method was employed to obtain the solution. The method used a two-step strategy to approximate the displacement response of the CT specimen. The first step was to obtain the general form of displacement solution, and then, the Rayleigh-Ritz approach was employed to modify the solution of the first step. A compliance equation of the CT specimen was obtained, and furthermore, the formula to calculate the stress intensity factor was obtained. The solution was validated by finite element (FE) model and the formula specified in ASTM E399-19 (2019). It was concluded that the calculation results of the proposed solution agreed well with the results of the FE model prediction for the ratio of initial crack length-to-ligament length, which was in the range of 0.25 to 0.35. Furthermore, compared to the results predicted by using the formula addressed in ASTM E399-19 (2019), the method proposed in the present study can achieve closer results than that of the FE model.

Α Nano Approach to Consolidation of Degraded Historic Lime Mortars

2009 ◽  
Vol 8 ◽  
pp. 13-22 ◽  
Author(s):  
Miloš Drdácký ◽  
Zuzana Slížková ◽  
Gerald Ziegenbalg
Keyword(s):  
Comparative Study ◽  
Calcium Hydroxide ◽  
Isopropyl Alcohol ◽  
Mechanical Characteristics ◽  
Colloidal Suspensions ◽  
Standard Test ◽  
Barium Hydroxide ◽  
Lime Mortar ◽  
Lime Water ◽  
Lime Mortars

This paper presents a comparative study of the effects of calcium hydroxide based agents on consolidating a lean lime mortar. In the first part, it describes the properties and characteristics of CaLoSiL® – a new stone strengthener based on colloidal suspensions of lime nanoparticles in various solvents. It further summarizes the results of recent tests on the influence of applying nano-agents based on colloidal calcium hydroxide dispersed in ethanol or isopropyl alcohol (CaLoSiL®), and compares them with the effects of lime water and with a traditional barium hydroxide treatment. The tests were carried out on non-standard test specimens fabricated from a lean mortar (1:9) and developed specially for the purpose of testing the relatively low strengthening effects that are typical for lime water consolidation. The comparison presented in this paper is based on the mechanical characteristics of consolidated lime mortar.

scholarly journals Assessing the Financial Feasibility of Slope Protection Through the use of Geocell With Recomposed of Infertile

2019 ◽  
Vol 7 (10) ◽  
pp. 745-760
Author(s):  
Dário Etsuro Haji Júnior ◽  
Estephison Montagnini e Silva ◽  
Igor Bezerra de Lima ◽  
David Barbosa de Alencar ◽  
Camily Murrieta Vasconcelos Oliveira Bezerra
Keyword(s):  
Granular Materials ◽  
Mechanical Characteristics ◽  
Load Capacity ◽  
Economic Viability ◽  
Economic Aspects ◽  
Financial Feasibility ◽  
Soil Cement ◽  
Small Load ◽  
Confinement System

Soils that have small load capacity need to have their mechanical characteristics improved in order to portray parameters that provide safety to the desired works. The geocells were developed to obtain a cellular confinement system used for reinforcement, protection and coating of slopes, similar to a beehive, which can be filled with soil, granular materials or concrete. However, the present work presents economic viability methods between the projected concrete and the geotextile. With the methodology, it was considered that the alternative use of geocell promoted savings of 35% compared to the projected concrete. The results indicated by tables that compose the projected concrete coatings and geocells were made available by the executing company. Finally, the method was applied to the soil-cement satisfactorily serving the execution, mechanical and economic aspects.

scholarly journals Numerical Study on Uniaxial Compression Behavior of Geobags

2019 ◽  
Vol 8 (4) ◽  
pp. 137-148
Author(s):  
N. Hataf ◽  
M. Javahery
Keyword(s):  
Bearing Capacity ◽  
Coastal Erosion ◽  
Mechanical Characteristics ◽  
Numerical Study ◽  
Load Capacity ◽  
Computer Software ◽  
Compressive Load ◽  
Friction Angle ◽  
Test Results ◽  
Compression Behavior

Geobags have been used as coastal erosion control and flood preventing measures during the last decades. More recently engineers have used geobags to improve the bearing capacity of soft soils. In this paper, a study was performed to investigate the behavior of geobags under compression loadings utilizing a finite element computer software. The numerical modeling was verified by simulating reported laboratory compression test results. The effects of various parameters such as geobag’s dimensions, mechanical characteristics of filling soil and bag material properties on the ultimate bearing capacity of geobags were investigated. It was shown that increasing the friction angle of filling soil and the tensile strength of textile lead to an increase in the geobag ultimate compressive load capacity. On the other hand, an increase in dilation angle of filling soil, Poisson's ratio and the height of geobag lead to a decrease in the ultimate compressive load capacity of geobags.

scholarly journals The Analysis of Beam-Column Joint Reinforced with Cross Bars according to SK SNI T-15-1991-03 on Cyclic Loads

2021 ◽  
pp. 1-10
Author(s):  
Zardan Araby ◽  
Samsul Rizal ◽  
Abdullah ◽  
Mochammad Afifuddin
Keyword(s):  
Test Specimen ◽  
Cyclic Load ◽  
Load Capacity ◽  
Maximum Load ◽  
Cyclic Loads ◽  
Concrete Compressive Strength ◽  
Dissipation Energy ◽  
Column Joint ◽  
The Moment ◽  
Inelastic Region

The primary structural component supporting the other structural loads in a building is the beam-column joint. It is considered a critical area of a building which needs to be accurately designed to ensure energy is dissipated properly during the occurrence of an earthquake. Beam-column joint has the ability to offer a proper structure required to transform cyclic loads in the inelastic region but also has a direct impact on the components connected to it during the occurrence of any failure. This is one of the reasons the beam-column connection needs to be designed carefully. Therefore, this study focused on designing a beam-column joint with reinforcement according to SK SNI T-15-1991 in order to withstand cyclic loads. The test specimen used was observed to have a concrete compressive strength of 19.17 MPa while the dimension of the beam was 120 x 30 x 40 cm and the column was 30 x 30 x 200 cm, having 8Ø13.4 mm bars with 310.03 MPa yield strength (fy) as well as Ø9.8-100 mm stirrup reinforcement with (fy) 374.59 MPa. The test was initiated through the provision of 0.75 mm, 1.5 mm, 3 mm, 6 mm, 12 mm, 24 mm monotonic cyclic loads at the end of the beam up to the moment the specimen cracked. A maximum load of 68.35 kN for the compression and 49.92 kN for the tension was required to attain the cyclic load capacity. The maximum load was attained at 50.98 mm displacement. Furthermore, beam-column with 23.93 mm displacement caused a reduction in capacity. Meanwhile, the load at 24 mm produced the cycle's highest dissipation energy of 13.25 but this can be increased through the addition of stirrups to provide stiffness in the joint. The stiffness value was also observed to have increased after the structural repairs.

Forming of 7075-T6 Aluminum in High Pressure Environments

1972 ◽  
Vol 94 (3) ◽  
pp. 595-598
Author(s):  
R. L. Pendleton ◽  
R. L. Davis
Keyword(s):  
Finite Element ◽  
Test Specimen ◽  
Effective Strain ◽  
Major Axis ◽  
Accurate Data ◽  
Compression Tests ◽  
Finite Element Stress Analysis ◽  
Tension And Compression ◽  
Dependent Model ◽  
Compression Data

Plates of 7075-T6 Aluminum have been folded along a major axis in pressure environments of atmospheric, 20,000 psi, and 40,000 psi. A finite element computer program is used to determine the stress state in the plates at various loads. Tension and compression tests conducted in pressure environments up to 70,000 psi were used to construct models using effective stress, effective strain, and pressure as parameters to predict the behavior of the material under various stress conditions. A prediction of the occurrence of fracture in the folded plate was possible using the computer results and the pressure dependent model. As better finite element stress analysis programs become available, both the forming operation and the test specimen can be analyzed to provide more accurate data that can be coupled with tension and compression data to predict the performance of metalforming operations under pressure.

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