scholarly journals Three-Point Bending Tests of Zirconia Core/Veneer Ceramics for Dental Restorations

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Massimo Marrelli ◽  
Carmine Maletta ◽  
Francesco Inchingolo ◽  
Marco Alfano ◽  
Marco Tatullo
Keyword(s):  
Surface Roughness ◽  
Comparative Study ◽  
Mechanical Strength ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Dental Restorations ◽  
Modes Of Failure ◽  
Cad Cam

Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out.Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872). Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests.Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers.Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

scholarly journals Mechanical Characterization and Machinability Behavior of Annealed AISI D6 Cold Working Steel

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Manoj Nayak ◽  
Rakesh Sehgal ◽  
Rajiv Kumar Sharma
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Cutting Speed ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Depth Of Cut ◽  
Factors Affecting ◽  
Approach Angle ◽  
Aisi D6 Steel ◽  
Significant Factors

Tool steels in metal forming industry are exposed to complex and aggressive conditions due to multiple effects (mechanical, thermal, or tribological loading) and require defined mechanical properties. Also machining of tool steel with poor machinability like AISI D6 to manufacture form tools is an extremely difficult task. This paper investigates the microstructural, mechanical, and machining behavior of AISI D6 steel in annealed and hardened conditions. Various mechanical tests indicated good hardenability, improved surface hardness, and phenomenal improvement in tensile strength but extremely poor resistance to impact in both annealed and hardened condition for this steel. The machining characteristics of AISI D6 steel were evaluated using a 2k unreplicated full factorial design approach and statistical techniques have been used to assess and identify the significant factors, namely, cutting speed, feed, depth of cut, and approach angle, in minimizing surface roughness and main cutting force while machining this steel with a carbide tool. It was found that the depth of cut, feed, and approach angle are the most significant factors affecting the surface roughness and depth of cut and feed affect the main cutting force. Cutting speed has no effect on surface roughness and main cutting force in machining of the steel in annealed condition.

scholarly journals Report on laboratory tests of sandstone and porphyry for rock fracture analysis

2020 ◽  
Vol 19 (2) ◽  
pp. 087-100
Author(s):  
Jakub Gontarz ◽  
Jacek Szulej
Keyword(s):  
Tensile Strength ◽  
Rock Fracture ◽  
Strain Energy Release ◽  
Mechanical Tests ◽  
Bending Test ◽  
Compression Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Bending Of Beams ◽  
Brazilian Method

The paper presents the results of mechanical tests of three types of rocks from stone mines in Poland. Compression tests of cubic samples, three-point bending tests of beams, bending of beams with notch and testing of tensile strength using the quasi-Brazilian method were performed. Based on the tests, the compressive strength, tensile strength, Young's modulus, and Poisson's ratios were determined. The stress intensity factor and critical strain energy release rate in mode I were determined from the bending test of the notched beams. The determined values were used as parameters of computer models which are used to verify the authors’ method of predicting the crack propagation in the Abaqus FEA system.

Influence of thermal and pH cycles on surface characteristics lithium disilicate glass-ceramic dental crowns milled with CAD/CAM process

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yajvinder Singh ◽  
Vishal Gulati
Keyword(s):  
Surface Roughness ◽  
Glass Ceramic ◽  
Research Work ◽  
Surface Hardness ◽  
Surface Characteristics ◽  
Lithium Disilicate ◽  
Content Type ◽  
Cad Cam ◽  
Group 3 ◽  
Group 2

Purpose The paper aims to evaluate the influence of thermo-chemical cycles of oral fluids on the surface attributes (roughness and microhardness) of lithium disilicate glass-ceramic (LDC) crown restorations manufactured with CAD/CAM technology. Design/methodology/approach There have been 24 LDC crowns manufactured using the CAD/CAM process for their respective preparation dies ply methyl methacrylate (PMMA) of mandibular left second premolar tooth (n = 8 each group). The standard procedure was used to glaze 16 crown samples (Groups 2 and 3).Samples of Group 3 were aged with thermal (563°C and 5563°C) and pH (2–14) cycles. All 24 samples were tested with a Profilometer and a Vicker hardness tester was used for their surface roughness and hardness measurement, respectively. Findings In statistical examination on SPSS Statistics 20 (IBM) software, of surface roughness values (Ra) and Vicker hardness values from different groups, Tukey HSD test was executed in one-way ANOVA (a = 0.05). The means Ra for groups were accordingly Group 3 > Group1 > Group 2 (p < 0.001). Similarly, micro-hardness was in order of Group 2 > Group 1 > Group 3 (p < 0.001). Research limitations/implications The research work does not have any limitations. Originality/value Surrounding temperature and pH significantly impact the surface characteristics of lithium disilicate crown restoration. The study also reveals the inverse relationship between surface roughness and surface hardness parameters. The observed results and facts revealed well in agreement with the past research studies.

scholarly journals Influence of the Printing Angle and Load Direction on Flexure Strength in 3D Printed Materials for Provisional Dental Restorations

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3376
Author(s):  
Paula Derban ◽  
Romeo Negrea ◽  
Mihai Rominu ◽  
Liviu Marsavina
Keyword(s):  
Statistical Analysis ◽  
Testing Machine ◽  
Load Direction ◽  
Flexure Strength ◽  
Three Point Bending ◽  
Dental Restorations ◽  
Frequent Use ◽  
Cad Cam ◽  
3D Printed ◽  
Printed Materials

The CAD/CAM techniques, especially additive manufacturing such as 3D printing, constitute an ever-growing part of obtaining different dental appliances and restorations. Of these, provisional restorations are of frequent use in daily dental practice and are the object of this study. Masticatory and parafunctional forces determine flexure on these prostheses. This study investigates the influence of the printing angle and loading direction of the applied force on the flexure strength of two commercially available printable resins—Detax Freeprint Temp and Nextdent MFH Vertex dental. Ten rectangular beam specimens printed at the angle of 0, 45 and 90 degrees were fabricated of each of these materials, with an addition of 10 at 0 degrees for the investigation of the load direction. Three-point bending tests were performed in a universal testing machine. Flexure strength, strain at break and Young’s modulus were determined and a statistical analysis was performed on the obtained data. According to the statistical analysis, the flexural strength has a significance dependence with respect to degrees of orientation, for both investigated materials.

Validation of an Analytical Model Describing Mechanical Properties of Porous BCP Ceramics

2007 ◽  
Vol 361-363 ◽  
pp. 15-18
Author(s):  
François Pecqueux ◽  
Nathalie Payraudeau ◽  
Franck Tancret ◽  
Jean Michel Bouler
Keyword(s):  
Mechanical Properties ◽  
Biphasic Calcium Phosphate ◽  
Bone Substitutes ◽  
Mechanical Tests ◽  
Cold Isostatic Pressing ◽  
Bending Tests ◽  
Three Point Bending ◽  
Conventional Sintering ◽  
Critical Flaw ◽  
Modelling Approach

Macroporous biphasic calcium phosphate bioceramics, for use as bone substitutes, have been fabricated by cold isostatic pressing and conventional sintering, using naphthalene particles as a porogen to produce macropores. The resulting ceramics, composite materials made of hydroxyapatite and β-tricalcium phosphate containing various macroporosities and microporosities, have been submitted to compression and three-point bending tests. The mechanical tests performed on the sintered ceramics tend to validate the modelling approach and its hypothesis, i.e. the material can be considered as a microporous matrix containing isolated macropores, and the critical flaw is a macropore.

A study on mechanical properties of Al5052/CFRP/Al5052 composite through three-point bending tests and shear lap tests according to surface roughness

2016 ◽  
Vol 54 (12) ◽  
pp. 1549-1559 ◽  
Author(s):  
MS Lee ◽  
SJ Kim ◽  
OD Lim ◽  
CG Kang
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Bending Test ◽  
Shear Load ◽  
Side View ◽  
Bending Tests ◽  
Three Point Bending ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Hybrid Sample

In this study, aluminum samples with various microsurface roughness values were produced by sandblasting to investigate the effect of the Ra (Surface roughness) value on the samples’ mechanical properties. Toward this end, a carbon fiber reinforced plastic/Al5052 hybrid sample was produced, and its mechanical properties were investigated through a tensile test, three-point bending test, and shear lap test. The theoretical and experimental tensile strength values of the hybrid composite were compared. During the bending test, CFRP and AI5052 separated in untreated specimens. A side-view examination revealed that the adhesion was best when the surface roughness was greatest ( Ra = 1.2 µm). Furthermore, shear load increased with the surface roughness. Therefore, the surface treatment was a crucial factor in making the specimen surface even and in increasing the roughness and therefore improving adhesion.

scholarly journals Fracture Behavior of Single-Crystal Sapphire in Different Crystal Orientations

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 930
Author(s):  
Shizhan Huang ◽  
Jiaming Lin ◽  
Ningchang Wang ◽  
Bicheng Guo ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Surface Roughness ◽  
Single Crystal ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Fracture Morphology ◽  
High Tech ◽  
Bending Tests ◽  
Three Point Bending ◽  
Single Crystal Sapphire

In order to study the anisotropy of fracture toughness and fracture mechanism of single-crystal sapphire, the three-point bending tests and the single-edge V-notch beam (SEVNB) were used to test the fracture toughness of A-plane, C-plane, and M-plane sapphire, which are widely used in the semiconductor, aerospace, and other high-tech fields. Fracture morphology was investigated by a scanning electron microscope and three-dimensional video microscopy. The fracture toughness and fracture morphology of different crystal planes of sapphire showed obvious anisotropy and were related to the loading surfaces. C-plane sapphire showed the maximal fracture toughness of 4.24 MPa·m1/2, and fracture toughness decreases in the order of C-plane, M-plane, and A-plane. The surface roughness is related to the dissipation of fracture energy. The surface roughness of the fracture surface is in the same order as C-plane > M-plane > A-plane. The fracture behavior and morphology of experiments were consistent with the theoretical analysis. C-plane sapphire cleavages along the R-plane with an angle of 57.6 degrees and the rhombohedral twin were activated. M-plane and A-plane sapphire cleavages along their cross-section.

scholarly journals Effect of Fibrillated Cellulose on Lime Pastes and Mortars

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 459
Author(s):  
Chiara D’Erme ◽  
Walter Remo Caseri ◽  
Maria Laura Santarelli
Keyword(s):  
Isothermal Calorimetry ◽  
Green Buildings ◽  
Mechanical Tests ◽  
Nitrogen Gas ◽  
Early Hydration ◽  
Bending Tests ◽  
Cement Production ◽  
Three Point Bending ◽  
Promising Solution ◽  
Mechanical Performances

The use of nanocellulose in traditional lime-based mortars is a promising solution for green buildings in the frame of limiting the CO2 emissions resulting from Portland Cement production. The influence of the fibrillated cellulose (FC) on lime pastes and lime-based mortars was studied incorporating FC at dosages of 0%, 0.1%, 0.2% and 0.3wt% by weight of binder. The lime pastes were subjected to thermal and nitrogen gas sorption analyses to understand if FC affects the formation of hydraulic compounds and the mesoporosities volume and distribution. The setting and early hydration of the mortars were studied with isothermal calorimetry. The mechanical performances were investigated with compressive and three-point-bending tests. Furthermore, fragments resulting from the mechanical tests were microscopically studied to understand the reinforcement mechanism of the fibres. It was found that 0.3wt% of FC enhances the flexural and compressive strengths respectively by 57% and 44% while the crack propagation after the material failure is not affected.

scholarly journals Comparison of the Effects of Sugar-free Solutions, Cola, Mouthwash on the Surface Hardness and Roughness of Temporary Crown Materials

2022 ◽  
Vol 58 (4) ◽  
pp. 197-209
Author(s):  
Nuran Yanikoglu ◽  
Zeynep Yesil Duymus ◽  
Sebahat Findik Aydiner
Keyword(s):  
Surface Roughness ◽  
Oral Cavity ◽  
Analysis Of Variance ◽  
Traditional Method ◽  
Surface Hardness ◽  
Micro Hardness ◽  
Restorative Materials ◽  
Cad Cam ◽  
Hardness Values

The aim of this study is to investigate the effect of polishing with different solutions on the surface roughness and hardness of two different polymethylmethacrylate temporary restoration materials. In the study, two different temporary crown materials prepared in the CAD / CAM system and prepared by the traditional method were used to test a total of 224 pieces of 10 mm diameter and 2 mm thickness. After the surface roughness and micro hardness values were measured, samples were randomly divided into seven groups among themselves; After waiting 24 h, 1 and 3 weeks, values were measured again. Data were evaluated using 3-way analysis of variance (ANOVA) and Tukey HSD test. The temporary restorative materials surface hardness and roughnesses are important to be able to stay in oral cavity without any changes. And it is also important to determine which of the materials (prepared by temporary conventional materiels or by the CAD/CAM) are less effected by the liquids in oral cavity.

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