Element Stress Research Articles

Stress and wavefront measurement of large-aperture optical components with a ptychographical iterative engine.

The clamping stress of large-aperture optical elements has a significant influence on the optical quality of the system. In this study, a comprehensive measurement system combined with ptychographical iterative engine (PIE) wavefront sensors and polarization components is developed to determine the stress distribution of the optical elements and its effect on the transmitted and reflected wavefronts. This system avoids the use of multiple measuring instruments and has low cost and strong anti-interference ability. The experimental results demonstrate that the stress distributions measured at different resolutions are consistent with the finite element analysis, and the wavefront measurement accuracy is 0.1λ. This test configuration is very flexible and provides a useful means for online installation and quality control of large-aperture optical systems.

Hydrogen diffusion and precipitation under non-uniform stress in duplex zirconium nuclear fuel cladding investigated by high-resolution neutron imaging

With the rising burn-up of nuclear fuel rods, the influence of hydrogen is of great importance when considering formation of brittle hydrides and their potential to the detriment of the mechanical integrity of nuclear fuel cladding. This work presents investigations on hydrogen diffusion and hydride precipitation in an unirradiated duplex cladding in response to thermo-mechanical cycles, by using high-resolution neutron imaging in correlation with finite element stress computation and hydride metallography analysis. The results demonstrate that the external stress, depending on the specific distribution, can work reversely or synergistically with the material heterogeneity in hydrogen migration. The material heterogeneity is identified as the prevailing driving force for hydrogen diffusion, whereas the applied stress contributes to hydrogen field variation only locally. Hydride precipitation is found to be significantly restrained in compressed area. In the presence of tensile hoop stress, hydride reorientation-induced elevation 40∼60 wppm of hydrogen concentration is identified, which could be attributed to the precipitation temperature difference between the radial and circumferential hydrides.

Simultaneous identification of multi-parameter for power hardening elastoplastic problems in three-dimensional geometries

PurposeThe purpose of this study is to simultaneously determine the constitutive parameters and boundary conditions by solving inverse mechanical problems of power hardening elastoplastic materials in three-dimensional geometries.Design/methodology/approachThe power hardening elastoplastic problem is solved by the complex variable finite element method in software ABAQUS, based on a three-dimensional complex stress element using user-defined element subroutine. The complex-variable-differentiation method is introduced and used to accurately calculate the sensitivity coefficients in the multiple parameters identification method, and the Levenberg–Marquardt algorithm is applied to carry out the inversion.FindingsNumerical results indicate that the complex variable finite element method has good performance for solving elastoplastic problems of three-dimensional geometries. The inversion method is effective and accurate for simultaneously identifying multi-parameters of power hardening elastoplastic problems in three-dimensional geometries, which could be employed for solving inverse elastoplastic problems in engineering applications.Originality/valueThe constitutive parameters and boundary conditions are simultaneously identified for power hardening elastoplastic problems in three-dimensional geometries, which is much challenging in practical applications. The numerical results show that the inversion method has high accuracy, good stability, and fast convergence speed.

Molecular evolutionary analysis of the SHI/STY gene family in land plants: A focus on the Brassica species.

The plant-specific SHORT INTERNODES/STYLISH (SHI/STY) proteins belong to a family of transcription factors that are involved in the formation and development of early lateral roots. However, the molecular evolution of this family is rarely reported. Here, a total of 195 SHI/STY genes were identified in 21 terrestrial plants, and the Brassica species is the focus of our research. Their physicochemical properties, chromosome location and duplication, motif distribution, exon-intron structures, genetic evolution, and expression patterns were systematically analyzed. These genes are divided into four clades (Clade 1/2/3/4) based on phylogenetic analysis. Motif distribution and gene structure are similar in each clade. SHI/STY proteins are localized in the nucleus by the prediction of subcellular localization. Collinearity analysis indicates that the SHI/STYs are relatively conserved in evolution. Whole-genome duplication is the main factor for their expansion. SHI/STYs have undergone intense purifying selection, but several positive selection sites are also identified. Most promoters of SHI/STY genes contain different types of cis-elements, such as light, stress, and hormone-responsive elements, suggesting that they may be involved in many biological processes. Protein–protein interaction predicted some important SHI/STY interacting proteins, such as LPAT4, MBOATs, PPR, and UBQ3. In addition, the RNA-seq and qRT-PCR analysis were studied in detail in rape. As a result, SHI/STYs are highly expressed in root and bud, and can be affected by Sclerotinia sclerotiorum, drought, cold, and heat stresses. Moreover, quantitative real-time PCR (qRT-PCR) analyses indicates that expression levels of BnSHI/STYs are significantly altered in different treatments (cold, salt, drought, IAA, auxin; ABA, abscisic acid; 6-BA, cytokinin). It provides a new understanding of the evolution and expansion of the SHI/STY family in land plants and lays a foundation for further research on their functions.

Inserting an Erroneous Element in the Answer Key of Grouped Team Readiness Assurance Test in Team-Based Learning: A Randomized Controlled Trial in Clinical Toxicology.

PurposeTeam-based learning (TBL) is an interactive instructional strategy designed to enhance student engagement. Few studies reported that TBL needs to be more interactive, concerns were raised regarding the insufficient instructor feedback, and students feel that TBL gets less attractive with time. One method of boosting students’ interaction and performance is adding an element of challenge or positive stress. Therefore, we hypothesized that inserting an erroneous answer in the answer key would generate an observable improvement in the selected outcomes in terms of better satisfaction, interaction, interest in learning, better academic performance, and better development of competencies compared to traditional TBL.MethodsThis randomized controlled trial aimed to determine if inserting an erroneous element in the answer key of a grouped team readiness assurance test (GRAT) would update TBL and whether this intervention would enhance students’ performance and satisfaction.ResultsA total of 55 medical students were recruited (88.7% response rate). Erroneous elements were inserted in the answer key of the experimental group and students enrolled in traditional TBL were considered as controls. Compared to the control group (p < 0.001), the experimental group revealed significantly higher academic performances in GRAT and team evaluation test (TET). Analysis of students’ perception of the implemented TBL revealed better perception among the experimental group (33.7 ± 6.4) than the control group (30.1 ± 7.0). Moreover, significantly higher team dynamics were reported among the experimental group than the control group (33.0 ± 6.3 and 27.8 ± 7.6 for both groups, respectively; p = 0.005). The reported advantages were in-depth understanding, easier information retrieval, and development of problem-solving skills. Students considered time and effort as their main limitations.ConclusionAdding a few erroneous answers in the GRAT is well perceived by students, enhances their learning competencies and overcomes some TBL challenges.

Fatigue life prediction of composite tidal turbine blades

Fibre reinforced polymer composites are frequently used in the design of tidal turbine blades where cyclic stresses brought on by the velocity fluctuations of tidal currents limit the in-service life of the blade. This paper presents a fatigue life prediction methodology for composite tidal turbine blades based on combined hydrodynamic and finite element structural models with the view to characterize the fatigue properties and failure modes of candidate composite material manufactured by vacuum assisted resin transfer moulding process. A hydrodynamic analysis is presented of the tidal flows over a typical tidal turbine blade. Using stream tube method, the temporal variations of tidal flows including the effect of support structure and waves provide the cyclic loading of the blades. The fatigue data for the tested material under realistic marine conditions is then used as input into the fatigue model which allows the prediction of the fatigue life. Incorporating fatigue failure modes with the finite element stress analysis of tidal turbine blades, showed that environmentally affected fatigue failure modes such as delamination is associated with blade root area when the blade is subjected to the cyclic tidal currents. Case study results for two commercial scale tidal turbine blades with energy output of 1.5 and 0.35 MW are shown to establish the methodology. The tidal turbine blade design methodology presented here can be used to assess the life expectancy of composite blade and tidal device energy production.

Research and Development of Hybrid Power Units Heat Flow Diagrams with Cooled High-Temperature Steam Turbines

Fossil fuel thermal power plants account for almost 60% of Russian electricity and heat. Steam turbine units make almost 80% of this amount. The main method for steam turbine unit efficiency improvement is the increase in the initial steam parameters’ temperature and pressure. This reduces fossil fuel consumption and harmful emissions but requires the application of heat-resistant steel. The improvement in steel’s heat resistance leads to a non-linear price increase, and the larger the temperature increase, the more the steel costs. One of the methods of improving efficiency without a significant increase in the capital cost of equipment is an external combustion chamber. These allow an increase in the steam temperature outside the boiler without the need to use heat-resistant alloys for boiler superheaters and steam pipelines between the boiler and the steam turbine. The most promising is hydrogen–oxygen combustion chambers, which produce steam with high purity and parameters. To reduce the cost of high-temperature steam turbines, it is possible to use a cooling system with the supply of a steam coolant to the most thermally stressed elements. According to the calculations, the efficiency reduction of a power unit due to the turbine cooling is 0.6–1.27%. The steam superheating up to 720 °C in external combustion chambers instead of a boiler unit improves the unit efficiency by 0.27%. At the initial steam temperatures of 800 °C, 850 °C, and 900 °C, the unit efficiency reduction caused by cooling is 4.09–5.68%, 7.47–9.73%, and 8.28–10.04%, respectively.

Investigation of the Effects of Adhesive Materials of Different Types and Thicknesses on Dental Tissue Stress via FEM Analysis.

The aim of this study was to investigate the types and thicknesses of adhesive materials used in restorative treatment in dentistry in class I occlusal and class II disto-occlusal cavities and to examine the effects of stress distribution on enamel, dentin, restoration material, and adhesive material using the finite element stress analysis method. A 3-dimensional geometry of the tooth was obtained by scanning the extracted 26 numbered upper molar tooth with dental tomography. The 3D geometry obtained by using the Geomagic Design X 2020.0 software was divided into surfaces, and necessary arrangements were made. With the Solidworks 2013 software, 2 different cavity modeling, class I occlusal and class II disto-occlusal, with a cavity angle of 95 degrees on the 3D model, as well as 10, 30, and 50 micrometers thick, four types of adhesive materials and the modeling of the bulk-fill composite material on it were made. With finite element stress analysis, the stress distribution was analyzed using the Abaqus software. The materials used in the study are included in the simulation as isotropic linear elastic. Periodontal ligament and jawbone were not included in the analysis. A total of 600 N pressure was applied on the models. In our study, it was observed that the amount of stress on the tooth structures changed when the thickness, elastic modulus, and Poisson ratios of the adhesive material were changed. In addition, when all models are examined, it is seen that when the thickness is increased, more stress is placed on the adhesive material compared to the restoration, while when 50-micrometer-thick adhesive material is used, more stress is placed on the restoration compared to the adhesive material.

Solid isotropic material with thickness penalization – A 2.5D method for structural topology optimization

SIMP is the most common topology optimization scheme to minimize the material utilization of a structural component using element densities as a design variable. This paper presents a new methodology, SIMTP, Solid Isotropic Material with Thickness Penalization, introducing a nodal thickness variable to the plane stress element. SIMTP uses a 2.5D element, and it is developed considering the varying thickness as a 3D problem and planar transformation as a 2D problem. The developed 2.5D element is used for projecting the 2D strain energy onto a 3D space. Classical optimization problems like Cantilever, MBB, and L-, beams are solved using 2.5D SIMTP, and results are compared with SIMP. The implementation is simple, directly representing the thickness, and nodal design variables enhance the resolution. Checkerboarding or other topology-related issues are not noticed during the process. Also, 2.5D SIMTP can yield desired results with fewer elements, thereby reducing the computational efforts. Besides, a 211-line MATLAB implementation of 2.5D SIMTP with examples is provided at the end of this paper.

Metalloprotein status in Indian patients with beta thalassemia trait

Introduction and Aim: Beta Thalassemia trait (BTT) is the most prevalent heterozygous hemoglobinopathy in Asian population. The current study aims to evaluate plasma antioxidant metalloproteins like SOD, ceruloplasmin, ferritin and correlate them with the trace elements in patients with BTT. Materials and Methods: The subjects included in the study were divided into two groups comprising of 40 BTT patients in group I and 40 age and sex matched normal individuals in group II. Cation exchange HPLC was used for hemoglobin variant analysis. Plasma iron, copper, ceruloplasmin and SOD were assayed using the spectrophotometric method while zinc was determined by atomic absorption spectrometry and ferritin by ECLIA. Results: There was a marked reduction in plasma trace elements in BTT compared to healthy controls. The decrease in zinc (p&lt;0.001) and copper (p&lt;0.04) was statistically significant. Both SOD and ferritin levels were significantly lower in BTT patients (p&lt;0.001). However, an apparent decrease was observed in ceruloplasmin levels. Iron and ferritin showed a significant positive correlation (r=0.84 p=0.01), similarly copper and ceruloplasmin correlated positively (r=0.92 p=0.001) in BTT patients. Interestingly HbF correlated negatively with all the three trace elements. Conclusion: It can be concluded that decreased antioxidant metalloproteins may lead to free radical toxicity in BTT. The study highlights the indirect role of trace elements in oxidative stress and draws attention on the requirement for regular and timely assessment of metalloenzymes and periodic administration of trace elements in reduction of free radical damage and associated complications in BTT patients.

Characterization of demethylating DNA glycosylase ROS1 from Nicotiana tabacum L.

One of the main mechanisms of epigenetic regulation in higher eukaryotes is based on the methylation of cytosine at the C5 position with the formation of 5-methylcytosine (mC), which is further recognized by regulatory proteins. In mammals, methylation mainly occurs in CG dinucleotides, while in plants it targets CG, CHG, and CHH sequences (H is any base but G). Correct maintenance of the DNA methylation status is based on the balance of methylation, passive demethylation, and active demethylation. While in mammals active demethylation is based on targeted regulated damage to mC in DNA followed by the action of repair enzymes, demethylation in plants is performed by specialized DNA glycosylases that hydrolyze the N-glycosidic bond of mC nucleotides. The genome of the model plant Arabidopsis thaliana encodes four paralogous proteins, two of which, DEMETER (DME) and REPRESSOR OF SILENCING 1 (ROS1), possess 5-methylcytosine-DNA glycosylase activity and are necessary for the regulation of development, response to infections and abiotic stress and silencing of transgenes and mobile elements. Homologues of DME and ROS1 are present in all plant groups; however, outside A. thaliana, they are poorly studied. Here we report the properties of a recombinant fragment of the ROS1 protein from Nicotiana tabacum (NtROS1), which contains all main structural domains required for catalytic activity. Using homologous modeling, we have constructed a structural model of NtROS1, which revealed folding characteristic of DNA glycosylases of the helix– hairpin–helix structural superfamily. The recombinant NtROS1 protein was able to remove mC bases from DNA, and the enzyme activity was barely affected by the methylation status of CG dinucleotides in the opposite strand. The enzyme removed 5-hydroxymethylcytosine (hmC) from DNA with a lower eff iciency, showing minimal activity in the presence of mC in the opposite strand. Expression of the NtROS1 gene in cultured human cells resulted in a global decrease in the level of genomic DNA methylation. In general, it can be said that the NtROS1 protein and other homologues of DME and ROS1 represent a promising scaffold for engineering enzymes to analyze the status of epigenetic methylation and to control gene activity.

New insights on the tectonic framework using EIGEN6C4 gravity data, seismicity, and finite element stress analysis: An attempt to map earthquake vulnerable zones in parts of North-East India and surroundings

Shillong Plateau and its surroundings experience frequent seismic activities characterised by the complex tectonic setup covering different parts of the Eastern Himalaya, Indo-Burma ranges and their conflux at the Assam syntaxis; which need further multivariate investigations. The present study deals with a combined analysis of EIGEN6C4 Bouguer gravity data, 56 years (1964–2020) seismicity data, 11 stations GPS velocity data (1996–2015) and focal mechanism of twelve earthquake events (1996–2017). We have enhanced Bouguer gravity data using the Theta derivative. Upward continuations of the Bouguer gravity were estimated at the heights of 5 km, 10 km, 20 km, 40 km, 60 km, and 100 km, which helped to infer the approximate persistent depth of the structures. Theta derivatives for the upward continued maps have also been estimated to enhance structures and fault zones at different approximated depths. Large numbers of smaller lineaments and shallow crustal smaller blocks are delineated at ∼2.5 km depth, whereas medium grade lineaments are mostly limited within the depth range of 2.5–25 km. However, relatively longer crustal-scale lineaments are highlighted at a greater depth of ∼30 km or more. Euler depth solutions of Bouguer gravity indicate a density heterogeneity interface in the depth range of 12–23 km that corroborates well with upward continuation results and past seismicity data. We have estimated Moho depth using the Parker-Oldenburg algorithm from the Bouguer gravity data. It delineates nine thin crustal structural features (S1–S9), twelve thick crustal structural features (D1-D12) and eleven crustal-scale lineaments (L1-L11) based on the distinct variations of Moho depths and their extensions. The b-value analysis indicates the highest order of b-value in the 15–30 km depth range, mainly in Mikir hill (∼1.7), the eastern part of Shillong Plateau (1.5) and the Indo-Burma ranges (2.3) that perhaps correlate well with the heterogeneity interface delineated by Euler depth solutions. The Eastern Himalaya generally exhibits characteristic low-Bouguer anomaly, high lineament density, low to moderate b-value, and deep-Moho/thick crust. The seismic stress model estimated using the finite element approach exhibits higher-order stress (∼34 MPa) around the central part of Shillong Plateau and at the northern part of Mikir hill with an SW-NE trend. Seismic stress correlates well with the regional lineament trend, GPS velocity/strain direction and low b-value, the joint analysis help to delineate a possible zone of future large earthquakes.

Identification and Bioinformatic Analysis of CAMTA Genes in Olive (Olea europaea L.)

Calcium is a secondary messenger which involves in stress response, adaptation, development and signaling pathways in plants. In cells, calcium is captured by calmodulin and after a conformation change, calmodulin becomes able to target calmodulin binding transcription factors. The calmodulin-binding transcriptional activators (CAMTAs) are one of these calmodulin binding transcription factors and they have CG-1, TIG, ANK, CaMBD and IQ conserved domains. CAMTAs are studied well in lots of plant species, and they are found to be involved in stress responses like drought, cold, salt and hormone responses like ethylene, abscisic acid, auxin, and gibberellin. In this study, CAMTA genes and proteins are characterized in olive. Olive (Olea europaea L.) is a Mediterranean commercially important crop, and this is the first study on olive CAMTAs. 7 CAMTA genes are found in olive in total in this study. Then, the cis-actin regulatory elements in the promoter regions of these genes are analyzed. Stress and hormone response related elements in the promoter regions are found, suggesting possible stress and hormone response roles of CAMTAs in olive. Also, protein characteristics, conserved domains, and subcellular localizations are investigated. According to the results, all olive CAMTA proteins are mainly localized in the nucleus as consistent with their roles, and all of them have 2 to 6 conserved domains which are also found in other plant CAMTAs. Additionally, a phylogenetic tree with 109 CAMTA proteins from well-knows plant species is constructed, and this tree showed that olive CAMTA proteins are highly conserved in plant kingdom.

Conceptualizing Multiple Stressors and Their Consequences in Agroforestry Systems

The natural environment of crops is exposed to a complex collection of biotic and abiotic pressures. Abiotic stresses cover a diversity of environmental elements that cannot be avoided, such as temperature, drought, salinity, cold, heat, light, and water stress. Biotic stress is caused by living organisms with which plants coexist and interact. Pathogens and herbivores are examples of biotic stressors that can threaten food security and result in significant economic losses. Agricultural production systems differ in the extent of stress towards cultivated crops; agroforestry is considered to provide a protective function against environmental stress. The concept of this review was to assess the impact of environmental change and the atmospheric variability on the plants in agroforestry systems. The application of trees in field crop production has become more and more involved in practice, especially in areas with an extreme climate and unfavorable soil conditions. The main reasons for the rising interest are the effects of climate change, soil degradation, and erosion. Most of the trees are used as hedgerows or farm boundaries, or as scattered planting on the farm to control soil erosion as well as to improve farm productivity, which requires a thorough understanding of each stress element.

Analyses of Pepper Cinnamoyl-CoA Reductase Gene Family and Cloning of CcCCR1/2 and Their Function Identification in the Formation of Pungency

Cinnamoyl-CoA reductases (CCR) have a possible role in pungency formation of pepper because they can convert feruloyl-CoA, sinapoyl-CoA, and p-coumaroyl-CoA into lignin, which are also competitive precursors of capsaicin biosynthesis in phenylpropanoid metabolism. In this study, genome-wide CCR gene family, exon–intron structures, sequence homology, phylogenetic characterization, and promoters were analyzed in pepper. Two CCR genes were cloned from Capsicum chinense, their enzymic kinetic parameters and regulatory function were identified by heterologous expression, ectopic expression, and VIGS. In total, 38 genes were found as predicted CCRs or CCR-like proteins and were composed of 2–10 exons. The promoters of pepper CCRs contained growth, stress, hormone, and light-response elements. The affinity and catalytic efficiency of CcCCR1/2 to feruolyl-CoA was the highest. The analysis of metabolic substances showed that capsaicin content was negatively correlated with lignin and positively correlated with flavonoids. The highest expression of CcCCR1 was found in stems, the higher expression of CcCCR2 was found in stem and early fruit than other organs. CCR1, 2 had certain effects on capsaicin content by regulating related enzyme activity, CCR2 played a more important role in regulating pungency formation. Our results clarify the competitive mechanism between lignin and capsaicin biosynthesis and provide an explanation for spice regulation.

An Efficient Sequential Strategy for Non-probabilistic Reliability-based Topology Optimization (NRBTO) of Continuum Structures with Stress Constraints

In the study, the sequential strategy is proposed for non-probabilistic reliability-based topology optimization (NRBTO) of continuum structures with stress constraints. Firstly, the qp-relaxation criterion is involved to circumvent the stress singularity. Then the deterministic topology optimization formulation by Stress-Influence-Function (SIF) approach is described. Uncertainty quantification analysis is conducted to determine the feasible bounds of the elemental stresses under unknown-but-bounded uncertainties. For safety reasons, the non-probabilistic reliability concept is introduced in the optimization formulation. The sequential strategy is proposed to handle the NRBTO problem and thus the original nested process of topology optimization and reliability analysis was decoupled, in which the update of design variables and the shift of the strength feature in the stress influence function are conducted alternately in the optimization process. The Performance Measure Approach (PMA) is applied to calculate the shift value of the strength feature and a shift value function is presented to avoid the numerical oscillations caused by the large variation of strength feature. Three numerical examples are eventually given to illustrate the applicability and validity of the developed sequential strategy for NRBTO with stress constraints.

A Comprehensive Study of the WRKY Transcription Factor Family in Strawberry.

WRKY transcription factors play critical roles in plant growth and development or stress responses. Using up-to-date genomic data, a total of 64 and 257 WRKY genes have been identified in the diploid woodland strawberry, Fragaria vesca, and the more complex allo-octoploid commercial strawberry, Fragaria × ananassa cv. Camarosa, respectively. The completeness of the new genomes and annotations has enabled us to perform a more detailed evolutionary and functional study of the strawberry WRKY family members, particularly in the case of the cultivated hybrid, in which homoeologous and paralogous FaWRKY genes have been characterized. Analysis of the available expression profiles has revealed that many strawberry WRKY genes show preferential or tissue-specific expression. Furthermore, significant differential expression of several FaWRKY genes has been clearly detected in fruit receptacles and achenes during the ripening process and pathogen challenged, supporting a precise functional role of these strawberry genes in such processes. Further, an extensive analysis of predicted development, stress and hormone-responsive cis-acting elements in the strawberry WRKY family is shown. Our results provide a deeper and more comprehensive knowledge of the WRKY gene family in strawberry.

Research on Structural Optimization Design of Plate Gate

The bulkhead gate of simple structure, easy fabrication, easy maintenance, safe and reliable degree is high, widely used in water conservancy and hydropower engineering, have stronger effects of spatial structure, this paper adopts three-dimensional finite element stress analysis, modeling and research of the relationship between the structure parameters and the structure performance, and then through the ANSYS software to optimize design. The analysis results show that the optimized gate has lighter weight and saves more materials under the condition of satisfying the strength and stiffness constraints.

Time History Method of Three-Dimensional Dynamic Stability Analysis for High Earth-Rockfill Dam and Its Application

Accurately grasping the stability characteristics of high earth-rockfill dam slopes is the key to the seismic safety evaluation of dams. In this research, the development and application of the common methods for slope stability analysis are reviewed firstly. Then, a three-dimensional dynamic time history stability analysis method is presented, and corresponding software is developed based on the sliding surface finite element stress method combined with the three-dimensional finite element dynamic response. This method makes the three-dimensional dynamic stability analysis efficient, and the effectiveness of this software is verified. Finally, the two-dimensional (2D) and three-dimensional (3D) dynamic stability analyses of a high concrete face dam are carried out, and the stability of the dam’s downstream slope under seismic load is studied. The results indicate that there are many differences between the results of the traditional 2D and 3D stability analyses. The time history of the safety factor, local safety behavior, overall shape and spatial position of the potential sliding body, and even the sliding process of failure can be captured with 3D stability analysis.

A Finite Element Stress Analysis of a Concical Triangular Connection in Implants: A New Proposal.

Conical implant–abutment connections are popular for their stability; however, in other conditions, such as excessive force, implants and abutments can absorb all the stress. Some connections with three points of support can resist more than conical connections. In recent years, different studies has shown that the design of a connection affects its stability. The aim of this study was to analyze and compare the stresses in finite elements (FEs) in a newly proposed conical triangular connection in implants with hexagonal and conical connections. A nonlinear 3D FE parametric model was developed using SOLIDWORKS 2017®. All the connections, i.e., external and internal hexagons, morse taper, conical connection, and the new conical triangular proposal were compared when axial forces of 150, 250, and 350 N were applied to the occlusal. The maximum stress was found in the external hexagon. The maximum stress was concentrated at the level of the neck of the abutment, implant, and bone, except for the morse taper; at the level of the crown and abutment, the lowest stress occurred in the new proposal. Conclusions: The new conical triangular (CT) connection and the conical connection (CC) generate similar stress in the implant, abutment, and crown. However, the CT connection improves the CC by reducing stress at the bone level, adding an advantage to having three retention points.