scholarly journals Evaluation of Mechanical Parameters at Compression Test for Different Restorative Composite Resins

2019 ◽  
Vol 56 (3) ◽  
pp. 592-595
Author(s):  
Andra Gamen ◽  
Gianina Iovan ◽  
Simona Stoleriu ◽  
Galina Pancu ◽  
Irina Nica ◽  
...  
Keyword(s):  
Compressive Strain ◽  
Mechanical Tests ◽  
Composite Resins ◽  
Mechanical Parameters ◽  
Compression Tests ◽  
Compression Behavior ◽  
Paired Samples ◽  
Kolmogorov Smirnov ◽  
Level Of Significance ◽  
Cylindrical Samples

The purpose of the present study was to evaluate the mechanical parameters at compression tests for two different restorative composite resins. The materials here under study were: Gradia Direct (GC Corporation, Tokyo, Japan) and Filtek Ultimate Universal Restorative, (3M ESPE, St. Paul, MN, USA). 30 cylindrical samples, 15 for each material, with a thickness of 6 mm and a diameter of 5 mm, were made. The compression behavior at mechanical tests for each sample was analyzed. One-Sample Kolmogorov-Smirnov Test followed by Paired Samples t-Test was used for statistical analysis and determining the level of significance. Gradia Direct had a lower value of Young�s modulus than Filtek Ultimate Universal Restorative, the results being statistically significant (p = 0.001 [ 0.05). The comparative evaluation of the compressive strength did not reveal statistically significant results between the two materials (p = 0.098 ] 0,05). Regarding the compressive strain the values were significantly lower for Filtek Ultimate Universal Restorative (p=0.000 [ 0.05). The microhybrid composite evaluated in the present study proved to have better mechanical properties than the nanofilled composite.

scholarly journals Comparative Study Regarding the Compressive Strength of Different Composite Resins Used for Direct Restorations

2018 ◽  
Vol 55 (3) ◽  
pp. 447-453
Author(s):  
Irina Nica ◽  
Gianina Iovan ◽  
Simona Stoleriu ◽  
Cristina Angela Ghiorghe ◽  
Galina Pancu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Compressive Strain ◽  
Mechanical Tests ◽  
Ultimate Compressive Strength ◽  
Composite Resins ◽  
Compression Behavior ◽  
Post Hoc ◽  
Cylindrical Samples ◽  
Scanning Electron

The aim of this study was to evaluate and to compare the compression behavior under identical mechanical tests, of three different composite resins, by determining Young�s modulus for compression, ultimate compressive strength and ultimate compressive strain. The studied materials were: Filtek Z250 Universal Restorative, Filtek Z550 and Filtek Bulk Fill Posterior Restorative (3M ESPE, St. Paul, MN, USA). Fifteen cylindrical samples, having 6 mm in height and 5 mm in diameter, were made from each material, using plastic molds. The samples were subjected to quantitative analysis of the compression behavior after mechanical tests. The fractured fragments of the samples were subjected to qualitative surface evaluation by scanning electron microscopy. Results were statistically analyzed using one-way analysis of variance (ANOVA) with Tukey�s post hoc test. Filtek Z250 had the lowest value of Young�s modulus for compression and the results were statistically significant (p[0.05) when compared to Filtek Bulk Fill Posterior Restorative and Filtek Z550. There were no statistically significant differences between all three materials regarding ultimate compressive strength (p]0.05). The lowest value for ultimate compressive strain was recorded for Filtek Bulk Fill.

Improvement of Collagen Hydrogel Scaffolds Properties by the Addition of Konjac Glucomannan

2011 ◽  
Vol 409 ◽  
pp. 187-192 ◽  
Author(s):  
Raquel Farias Weska ◽  
Matteo Achilli ◽  
Marisa Masumi Beppu ◽  
D. Mantovani
Keyword(s):  
Tissue Engineering ◽  
Vascular Tissue ◽  
Compressive Strain ◽  
Biological Properties ◽  
Mechanical Tests ◽  
Konjac Glucomannan ◽  
Spectrophotometric Analysis ◽  
Vascular Tissue Engineering ◽  
Compression Tests ◽  
Collagen Gels

Collagen gels have been investigated for a number of applications in tissue engineering because of their excellent biological properties. However, their limited mechanical behavior represents a major bottleneck for clinical use, especially for vascular tissue engineering. The targeting of their mechanical properties may be envisaged by the addition of other biopolymers, such as konjac glucomannan (KGM), a neutral high-molecular weight polysaccharide extracted from the tubers ofAmorphophallus konjac, which has already been studied for biomedical applications due to its biocompatibility and biodegradable activity. In the present study, reconstituted collagen gels were prepared at pH 10 and room temperature, by mixing collagen with NaOH, NaCl and 0.05 to 0.2% of KGM. Collagen fibrillogenesis was monitored by spectrophotometric analysis at 310 nm. Gel samples were analyzed by compression tests, FTIR and SEM. Comparing to the control, the addition of KGM reduced the half-time (t1/2) of gelation fromca. 3 h to 2 h and the mechanical tests showed increases in the compressive strain energy of up to 3 times, and in compressive modulus of almost 4 times. Scanning electron images of collagen gel samples with KGM revealed the presence of micro-domains of KGM in the collagen matrix, revealing a phase separated scaffold for vascular tissue engineering.

scholarly journals STUDY OF THE COMPRESSION BEHAVIOR OF SUNFLOWER SEEDS USING THE FINITE ELEMENT METHOD

AGROFOR ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Sorin-Ștefan BIRIȘ ◽  
Mariana IONESCU ◽  
Neluș-Evelin GHEORGHIȚĂ ◽  
Nicoleta UNGUREANU ◽  
Nicolae-Valentin VLĂDUȚ
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mechanical Tests ◽  
Sunflower Seeds ◽  
Compression Tests ◽  
The Finite Element Method ◽  
Compression Process ◽  
Fem Model ◽  
Compression Behavior ◽  
Element Method

It is known that the phenomena that occur during compression of sunflower seedsare very complex. Comprehension of these phenomena is important for increasingthe performance of the equipment in the vegetable oil industry, both for thecracking of shells and for the grinding of kernels. Also for the pressing of oilseedmaterials it is helpful to understand the compression behavior of sunflower seeds.The major objective of this work is to find an easy way of highlighting how thestresses and deformations propagate in sunflower seeds kernels and shells duringthe compression process, with the aim of optimizing the energy consumptionrequired for the mechanical processing. Therefore, now days there is and we canuse the finite element method. This method is the most advanced engineering toolfor computing numerical and mathematical modeling of complex phenomenainvolving the propagation of stress and strain fields in continuous media. In thispaper a two-dimensional FEM model for analyzing sunflower seeds subjected atcompression by axial and lateral directions is presented. For experimentalvalidation of FEM model we made uniaxial compression tests on sunflower seeds,using a Hounsfield/Tinius Olsen unit for mechanical tests, H1KS model. Themodels used in this work highlight that the orientation of the seeds is veryimportant. There are situations when it is desirable that the stresses to be higher (atshelling, grinding, pressing, etc.) or situations when it is desirable that the stressesto be smaller (at transport, storage, etc.).

A Study of the Mechanical Role of Enamel and Dentin in Human Teeth

2012 ◽  
Author(s):  
Keyoung Jin Chun ◽  
Hyun Ho Choi ◽  
Jong Yeop Lee
Keyword(s):  
Surface Hardness ◽  
Mechanical Tests ◽  
Indentation Load ◽  
Bite Force ◽  
Compression Tests ◽  
Healthy Human ◽  
Human Teeth ◽  
Diamond Indenter ◽  
Dental Hard Tissues ◽  
Measured Hardness

The dental hard tissues of a tooth are combined of enamel and dentin together. The enamel protects the dentin and comes in direct contact with food during mastication. Bite force is expressed as compression force. The purpose of this study is to identify the primary roles of enamel and dentin during mastication by analyzing their mechanical properties and hardness. Healthy human teeth (age: 19.3 ± 4.1) were used as specimens for mechanical tests. The teeth, which underwent epoxy resin molding, were machine cut to make 10 enamel specimens, 10 dentin specimens and 10 enamel–dentin composite (ED) specimens of 1.2 mm × 1.2 mm × 3.0 mm (Width × Height × Length) in size. Compression tests were conducted using a micro-load system at 0.1 mm/min test speed. Teeth surface hardness (HV) was measured by a Vickers diamond indenter with a 300g indentation load. Data were obtained from 4 points on each enamel specimen and 4 points on each dentin specimen. The strain (%), stress (MPa) and modulus of elasticity (E, MPa) of the specimens were obtained from compression tests. The MAX. strain of the enamel, dentin and ED specimens were 4.5 ± 0.8 %, 11.9 ± 0.1 % and 8.7 ± 2.7 %, respectively. The MAX. stress of the enamel, dentin and ED specimens were 62.2 ± 23.8 MPa, 193.7 ± 30.6 MPa and 126.1 ± 54.6 MPa, respectively. The E values of the enamel, dentin and ED specimens were 1338.2 ± 307.9 MPa, 1653.7 ± 277.9 MPa and 1628.6 ± 482.7 MPa, respectively. The E of the dentin specimens was the highest and the E of the enamel specimens was the lowest, but the E values of all specimens was not significantly different in the T-test (P > 0.1). The measured hardness value of the enamel specimens (HV = 274.8 ± 18.1) was about 4.2 times higher than that of the dentin specimens (HV = 65.6 ± 3.9). Because of the values of MAX. stress and MAX. strain of the enamel specimens, the enamel specimens tended to fracture earlier than the dentin and ED specimens; therefore, enamel was considered to be more brittle than dentin and ED. Enamel is a harder tissue than dentin based on their measured hardness values. Therefore, enamel has a higher wear resistance, making it suitable for grinding and crushing, whereas dentin has a higher force function, making it suitable for abutment against bite force.

A Newly Developed Clamping Device for the Tension/Compression Test at Various Strain Rates

2014 ◽  
Vol 626 ◽  
pp. 353-358
Author(s):  
Geun Su Joo ◽  
Min Kuk Choi ◽  
Hoon Huh
Keyword(s):  
Strain Rate ◽  
Sheet Metal ◽  
Metal Forming ◽  
Loading Condition ◽  
Strain Rates ◽  
Compression Tests ◽  
Compression Behavior ◽  
Compression Loading ◽  
Hardening Behavior ◽  
Clamping Device

The tension/compression hardening behavior is important in sheet metal forming processes because of complicated loading paths. Experimental methods to measure the tension/ compression behavior have not considered the effect of the strain rate although the strain rate is related to the hardening behavior of sheet metal. The tension/compression tests need to be conducted considering the strain rate to acquire accurate hardening behavior.This paper deals with an experimental technique to measure the tension/compression behavior of sheet metal at various strain rates. A new clamping device was developed to prevent a sheet specimen from buckling under compression loading condition. Compared to previous clamping devices, the clamping device was devised to uniformly impose a clamping force and easily measure the strain from side of a specimen. Tension/compression tests have been conducted at various strain rates for SPCC and DP590 with displacement of 10%. Hardening curves under the tension or compression loading condition were obtained and analyzed with respect to the strain rate.

scholarly journals The Effect of Transversal Connection in the in-Plane Response of Double-Leaf Brick Masonry Walls

2021 ◽  
Author(s):  
Lorenzo Scandolo ◽  
Stefano Podestà
Keyword(s):  
Structural Safety ◽  
Masonry Walls ◽  
Masonry Building ◽  
Mechanical Parameters ◽  
Compression Tests ◽  
Knowledge Process ◽  
Diagonal Compression ◽  
Set Up ◽  
Definition Of ◽  
Simplified Mechanical Model

Abstract The evaluation of structural safety derives from the knowledge of material properties. In case of existent masonry building, the definition of reliable mechanical parameters could be a very difficult task to be achieved. For this reason, an estimation of these values is useful, for example it is the first phase of the knowledge process, for simplified mechanical model or when NTD test is the only possibility.The transversal connection in masonry panels is a technological detail that affects the static and seismic behavior and could significantly increase the strength of the element.In this paper the effect of transversal connection in double-leaf brickwork masonry panels is evaluated by diagonal compression tests. To achieve this goal, a new set-up was designed to load each leaf independently.The results have shown an increment of about 20% in strength if transversal connection is present. If the leaves have very different mechanical parameters, the tests highlight an unexpected behavior.

Analysis of Coir Fiber Reinforced Poly-Lactic Acid (PLA) and Poly-Propylene (PP) Polymeric Composite

2016 ◽  
Vol 852 ◽  
pp. 10-15
Author(s):  
Sahas Bansal ◽  
M. Ramachandran ◽  
Pramod Raichurkar
Keyword(s):  
Lactic Acid ◽  
Natural Fibers ◽  
Polymeric Composite ◽  
Mechanical Tests ◽  
Composite Resins ◽  
Poly Lactic Acid ◽  
Coir Fiber ◽  
Scanning Calorimetry ◽  
Biodegradable Composite ◽  
Poly Propylene

Green composites shaped by mixture of biodegradable polymers and natural fibers have spellbound massive interest in current years due to their environmentally valuable properties and also to decrease our dependency on the non-renewable resources. Due to the environmental advantages and light weight of natural fibers, an increasing quantity of natural fibers has been used to replace synthetic fibers composites. Coir fiber poly-lactic acid (PLA)/ poly-propylene (PP) resin reinforced polymeric composites have been developed with 90o orientation. The composition of PLA and PP for resin preparation is taken in the ratio 95:05 whereas for the composite, resins and coir fiber in 80:20. The compression molding technique is applied and then the tests are carried out. Mechanical tests (Impact and Hardness), Micro structural analysis (Fourier Transform Infrared Spectroscopy and Optical Imaging) and Differential Scanning Calorimetry are conducted. According to the investigational verification, the new biodegradable composite shows significant results on par with synthetic/ man made composites and the advantages of using bio-composites has been indicated with simplicity.

scholarly journals Sensitivity Analysis in the Estimation of Mechanical Parameters of Engineering Rock Mass Based on the Hoek–Brown Criterion

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Zhiqiang Li ◽  
Guofeng Liu ◽  
Shuqian Duan ◽  
Shufeng Pei ◽  
Changgen Yan
Keyword(s):  
Rock Mass ◽  
Triaxial Compression ◽  
Damage Zone ◽  
Surrounding Rock ◽  
Geological Strength Index ◽  
Sensitivity Factor ◽  
Mechanical Parameters ◽  
Compression Tests ◽  
Disturbance Factor

Geological strength index GSI, disturbance factor (D), material constant mi, and uniaxial compressive strength σci of the intact rock are essential input parameters IPs of the Hoek–Brown H−B criterion. Mechanical parameters MPs of the engineering rock mass, including elastic modulus E, cohesion c, and internal friction angle φ estimated by the H–B criterion, and the predicted excavation response of surrounding rock, including the displacement and excavation damage zone EDZ based on the MPs, are of high relevance with the four IPs of the H–B criterion. In this paper, the deep and huge underground cavern excavated in basalt from a hydropower station under construction in the southwest of China is used to analyse the sensitivity of the IPs on the MPs, the displacement, and EDZ of the surrounding rock mass. Firstly, the H–B criterion is applied to estimate the MPs, among which the IPs are obtained from a series of in situ and laboratory tests, including borehole camera observation, wave velocity test, uniaxial and triaxial compression tests, and so on. Secondly, the sensitivity relationships between IPs, MPs, and prediction results of displacement and EDZ are established and described quantitatively by the sensitivity factor (si). Results show that the MPs of the rock mass are more sensitive to GSI and D⋅GSI and σci are high-sensitivity parameters affecting the displacement and EDZ. Finally, the variations in the estimated MPs and associated prediction results concerning excavation response, which are caused by the uncertainties in the determination of the IPs, are further quantified. This study provides a straightforward assessment for the variability of the rock mass parameters estimated by the H–B criterion. It also gives a valuable reference to similar geotechnical engineering for the determination of rock mass parameters in the preliminary design.

A Study on Compression Behavior of Warp Knitted Spacer Fabrics

2011 ◽  
Vol 332-334 ◽  
pp. 1036-1039
Author(s):  
Xiao Fang Guo ◽  
Hair U Long
Keyword(s):  
Surface Structure ◽  
Inclination Angle ◽  
Compression Rate ◽  
Compression Tests ◽  
Apparent Effect ◽  
Compression Behavior ◽  
Spacer Fabric ◽  
Spacer Fabrics ◽  
Chinese Standard ◽  
Compression Resistance

The influences of inner layer′s (spacer yarn′s) pattern, surface structure of fabric, thickness, and spacer yarn′s diameter on compression resistance of warp knitted spacer fabric were investigated in the study. The compression tests involving 10 samples were carried out by TexLab Precision Instruments CT250 based on Chinese standard FZ/T01051.2-1998. The results show that inner layer′s pattern and surface structure affect the compression resistance of spacer fabric by changing the inclination angle of spacer yarn, the closer spacer yarn keep vertical, the better compression resistance of fabric. The laws of force exerted on spacer yarn followed by fabric′s thickness differ according to compression rate, the compression resistance increases as the thickness increases when the deformation of fabric is small (less than 4.90%), but decreases when the deformation is large enough (more than 19.20%). The diameter of spacer yarn has apparent effect on compression resistance, and the fabric with finer spacer yarns has lower compression resistance.

scholarly journals Experimental Study on Axial Compression Behavior of Masonry Columns’ Strengthening with Bamboo Scrimber Bar Mesh Mortar Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Hongyao Liu ◽  
Min Lei ◽  
Bowang Chen
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Failure Process ◽  
Engineering Application ◽  
Compression Tests ◽  
Compression Behavior ◽  
Bamboo Scrimber ◽  
Calculation Results ◽  
Strengthening Method

We propose a new method to strengthen structural masonry. To study on the axial compression behavior of masonry columns’ strengthening with a bamboo scrimber bar mesh mortar layer, axial compression tests of twelve masonry columns have been completed: nine strengthened columns and three unstrengthened columns. The failure process, bearing capacity, and failure mode are carried out. The strengthening method of bamboo scrimber bar mesh mortar layer permits the upgrade of the columns’ bearing capacity. The effects of bamboo bar ratio and mortar strengthening ratio on bearing capacity of the reinforced columns are compared. We propose the method for calculating the axial bearing capacity of such a reinforced column. The calculation results agree well with the experimental results, and the research results are available for engineering application.

Sign in / Sign up

Export Citation Format

Share Document