Mechanical Characteristics Research Articles

Seeking orderness out of the orderless movements: an up-to-date review of the biomechanics in clear aligners

Abstract Introduction Although with increasing popularity due to aesthetic appeal and comfort, clear aligners (CAs) are facing challenges in efficacy and predictability. Advancement in the underlying biomechanical field is crucial to addressing these challenges. This paper endeavors to provide a comprehensive framework for understanding the biomechanics of CA and enlightening biomechanics-based improvements on treatment strategies. Methods A thorough review of the English-language literature accessible through PubMed and Google Scholar, without any publication year restrictions, was undertaken to unravel the biomechanical aspects of CA. Results This review presented an up-to-date understanding of aligner biomechanics arranged by the framework of the material-dependent mechanical characteristics of CA, the geometric characteristics-dependent force transmission of the CA system, methods for studying the biomechanics of CA, and the biomechanical analyses for different types of tooth movement. Conclusions Biomechanics should be the fundamental concern for concepts, methods and adjuncts attempting to enhance the accuracy and predictability of tooth movement induced by CA. Improvement on material properties and alteration of geometric design of CA are two main approaches to develop biomechanically optimized force system. Exploration of real-world force sensing and monitoring system would make substantial progresses in aligner biomechanics.

Disperse reinforcement of artificial base with glass waste

The article presents the results of laboratory stamp tests of sandy soils, the dispersed reinforcement of which was made with cullet waste in the form of crumbs. The tested soil samples had different densities and, accordingly, for each density, several options were made for the percentage of glass in the mass of the total volume. The purpose of the laboratory research was to obtain such a mechanical characteristic of the soil as the deformation modulus, which was subsequently compared with the same deformation modulus, but not of reinforced soil. The research results obtained showed the effectiveness of using glass chips as dispersed reinforcement of loose soils, which makes it possible to improve its strength properties and significantly save on the installation of artificial foundations for buildings or structures, as well as solve the issue of recycling glass waste and, accordingly, improve the environmental performance of the environment.

Investigation of mechanical characteristics and sustainable practices in concrete incorporating recycled marble waste

Due to the rapid expansion of infrastructure, urbanization, and industry, there is a constant need for concrete worldwide. However, the expansion of the concrete sector increases pressure on natural resources, endangering the balance of the ecosystem. Thus, it would be advantageous to meet current concrete needs without reducing production quality by incorporating recycled materials into concrete mixes. In this work, we investigate the mechanical characteristics of environmentally friendly concrete using recycled marble powder (WMP) partially replacing cement and marble coarse aggregates (MCA) as an alternative to natural coarse aggregates. The qualities of the concrete were evaluated using a combination of destructive and non-destructive testing techniques. In this study, three series of mixes were prepared. The first series (S1) is composed of 100% natural coarse aggregates. In the second series (S2), 50% of the natural coarse aggregates are substituted for marble coarse aggregates, while the third series (S3) is composed of 100% marble coarse aggregates. In each of the three series, Marble powder was used in place of cement at a percentage ranging from 5% to 20%, increasing by 2.5%. Concrete mixes were developed and evaluated with different levels of marble waste substitution to compare their compressive strengths and workability to those of traditional concrete made from 100% natural aggregates. Simultaneously, the strength characteristics were measured using the Schmidt hammer and ultrasonic velocity tests. As was mentioned, in the three series, when Cement is replaced with marble powder, the slump decreases, even though the incorporation of marble coarse aggregates tends to increase this workability, while the compressive strength shows an increase of 28.66% and 31.63% compared to the control mix for 50% and 100% substitute of natural coarse aggregates with marble coarse aggregates, respectively. It is also noteworthy that concrete containing marble waste exhibits normal ultrasonic velocity. For concrete mixtures of series (S1), (S2), and (S3), respectively, the velocity of ultrasonic pulses increased by 18.20%, 27.44%, and 27.98%, while the Schmidt Rebound Number increased by 10.13%, 14.52%, and 21.37%, respectively, in contrast to the values of the control mixture. Additionally, the reliability of results from the universal testing machine (UTM) was validated through correlation analysis of compressive strength measurements obtained by various methods. The study's findings are intriguing and underscore the potential of employing marble waste as an alternative to natural aggregates.

Shape memory resin for direct printed aligners: A scoping review

: This review aims at analyzing the literature available regarding the properties of the novel Tera Harz resin introduced to manufacture direct printed aligners in terms of its mechanical characteristics, accuracy, and cytotoxicity. Utilizing the databases of PubMed, Scopus, and the Cochrane Library, a search for publications published up until February 2024 was conducted by applying the search phrases ("3D printed" OR "three-dimensional printed") AND aligner AND (polymer* OR material* OR resin* OR technopolymer*). There were 620 records found in the first search. 220 studies were reviewed after duplicates were eliminated. A total of 196 complete texts were screened based on the title and abstract. 90 full-text papers had their eligibility evaluated. The qualitative synthesis contained 16 studies.With its ideal characteristics, the new shape memory resin has the potential to be a viable replacement for thermoformed aligners, offering greater accuracy and force delivery. The gathered data is still only somewhat reliable and quantitatively scarce. It is necessary to do more research to assess the therapeutic efficacy of these new materials.

Damage Characteristics and Mechanical Properties of DD6 Single‐Crystal Alloy Based on Crystal Plasticity Theory under Uniaxial Tensile Conditions

Herein, the mechanical behavior and damage characteristics of DD6 nickel‐based single crystal alloy under different crystal orientation conditions are studied based on the theory of crystal plasticity coupled with damage constitutive equations using the crystal plasticity finite‐element method. The results indicate that the crystal plastic finite‐element model coupled with damage constitutive equations can well describe the entire deformation process from elasticity to damage. Under the reference orientation condition, the damage starts from the center position inside the test specimen and extends to the surrounding areas. The stress value in the damaged area decreases gradually from the periphery to the center of the test specimen, and an external stress reduction zone is formed. The crystal exhibits the best elasticity properties in the [0, 1, 1] orientation and the best plasticity properties in the [0, tan22.5°, 1] orientation. As the rotation angle of crystal orientation increases, the damage zones of X‐Z, Z‐Y, and X‐Y sections all exhibit clockwise rotation characteristics.

Performance evaluation of controlled low-strength blended cement concrete modified with recycled waste materials

Purpose This work aims to investigate the feasibility of recycling waste plastic (polyethylene terephthalate) as a coarse aggregate for producing blended cement concrete modified with fly ash and pond ash. Design/methodology/approach The low, medium and high controlled strength blended cement concrete modified with varied proportions of fly and pond ashes were produced. Manufactured sand and recycled plastic coarse aggregate (RPCA) replaced normal fine and coarse aggregates. Concrete samples were tested for workability, mechanical and durability characteristics. Microstructural analysis was performed on cement concrete blended with fly and pond ashes and compared to conventional concrete samples. Findings All concrete mixes showed better flowability with values greater than 200 mm. Besides, the maximum flow time was approximately 8 s. The wet density of blended cement concrete-RPCA-based concretes was approximately 30% lower than that of conventional concrete. The compressive strengths of the controlled strength mix at 7 and 28 days were within the specified ranges. While the conventional concrete had slightly higher permeability, the blended cement concrete-RPCA-based concretes had better thermal resistivity and lower thermal conductivity. The scanning electron microscopy analysis revealed the densification of the microstructure due to the filler effects of fly and pond ashes. Originality/value This study establishes the prospects of substituting RPCA with normal coarse aggregate in the production of controlled low-strength blended cement concrete, offering benefits of structural fill concrete, lower permeability and thermal conductivity, higher thermal resistivity and reduced density and shrinkage.

Study on the Influence Characteristics of Excavation Face Instability of New Tunnels Orthogonally Crossing Existing Tunnels

This study aims to solve the problem of stability of the excavation surface of a new tunnel crossing an existing tunnel orthogonally. The relative horizontal spacing between the two tunnels is taken as an influencing factor, and transparent soil model tests are conducted and expanded with numerical simulations. Finally, the active destabilization mechanism and influence characteristics of the excavation surface of the two tunnels at different horizontal spacings, vertical spacings, and tunnel diameter ratios are obtained. The results show that when the excavated face is destabilized, the existing tunnel located in front of and above the excavation surface limits the development of the upper “silo” and the transfer of soil stress in the destabilized area, and the ultimate support pressure is reduced by 17.6% and 8.7%, respectively. This effect increases as the vertical spacing between the two tunnels decreases and the tunnel diameter ratio increases. At this point, the deformation trend of the existing tunnel cross-section is reflected as “elliptical-shaped”. This trend is more apparent when the vertical spacing between the two tunnels and the tunnel diameter ratio are decreased. The protection of the existing tunnel should be strengthened at this time.

Reactive powder concrete beam design using a mathematical software to reduce costs

AbstractReactive powder concrete is widely recognized for its remarkable mechanical characteristics and resilience, rendering it an ideal option for structural uses that include heavy loads. However, the intricate interaction of numerous material and geometric aspects makes constructing reactive powder concrete beams extremely difficult. By using MATLAB to provide an optimized design framework for beams, this research tackles these issues. Particle swarm optimization and evolutionary algorithms are two of the advanced techniques used in the study to solve the optimization problem. It also includes constraints other one as structural requirements and material limitations. Results demonstrate that MATLAB-based optimization facilitates effective design, lowering costs and material consumption, with potential for more applications in the building sector.

Mechanical Characteristics of Grillage Root Foundation for High-Voltage Tower Under Horizontal Conditions

Mechanical Characteristics of Grillage Root Foundation for High-Voltage Tower Under Horizontal Conditions

Concrete Creep Prediction Based on Improved Machine Learning and Game Theory: Modeling and Analysis Methods

Understanding the impact of creep on the long-term mechanical features of concrete is crucial, and constructing an accurate prediction model is the key to exploring the development of concrete creep under long-term loads. Therefore, in this study, three machine learning (ML) models, a Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting Machine (XGBoost), are constructed, and the Hybrid Snake Optimization Algorithm (HSOA) is proposed, which can reduce the risk of the ML model falling into the local optimum while improving its prediction performance. Simultaneously, the contributions of the input features are ranked, and the optimal model’s prediction outcomes are explained through SHapley Additive exPlanations (SHAP). The research results show that the optimized SVM, RF, and XGBoost models increase their accuracies on the test set by 9.927%, 9.58%, and 14.1%, respectively, and the XGBoost has the highest precision in forecasting the concrete creep. The verification results of four scenarios confirm that the optimized model can precisely capture the compliance changes in long-term creep, meeting the requirements for forecasting the nature of concrete creep.

Mimicking Osteoid 3D Porous Dense Microfiber Silk Fibroin Embedded Poly(vinyl alcohol) Scaffold for Alveolar Ridge Preservation

Abstract Alveolar ridge loss presents difficulties for implant placement and stability. To address this, alveolar ridge preservation (ARP) is required to maintain bone and avoid the need for ridge augmentation using socket grafting. In this study, a scaffold for ARP was created by fabricating a 3D porous dense microfiber silk fibroin (mSF) embedded in poly(vinyl alcohol) (PVA), which mimics the osteoid template. The research utilized a freeze-thawing technique to create a mimicked osteoid 3D porous scaffold by incorporating different amounts of mSF into the PVA, namely, 1%, 3%, 5%, and 7%. Subsequently, a 3D profilometer machine and a scanning electron microscope (SEM) were employed to examine the morphology and size of the mSF and the mimicked osteoid 3D porous scaffold in all groups. Thermal characteristics and crystalline structure were analyzed before assessing the water contact angle, swelling behavior, degradation, and mechanical properties. The experiment evaluated the biological performance of the mimicked osteoid 3D porous scaffold by examining the efficacy of osteoblast cell adhesion, proliferation, viability, protein synthesis, alkaline phosphatase (ALP) activity, and calcium synthesis. Finally, the ability of osteoblast cells to regulate the osteoid matrix deposition on the osteoid 3D porous scaffold was assessed by mimicking the dynamic bone environment using rat mesenchymal stem cells (RMSC). The findings suggest that incorporating mSF into PVA enhances the interconnective pore size, crystalline structure, and thermal behavior of the mimicked osteoid 3D porous scaffold. The hydrophilicity of PVA decreased with an increase in the proportion of mSF, while a higher proportion of mSF resulted in increased swelling and mechanical characteristics. Incorporating a greater proportion of mSF, specifically 5% and 7%, led to a reduced rate of degradation. The addition of 5% mSF to the PVA 3D porous scaffold resulted in remarkable biological properties and excellent osteoconductive activity.

Carbon-based nanocomposites for sensing applications-a review

Abstract Carbon-based nanomaterials exhibit unique morphological and physical properties. When used as fillers in various matrices such as polymers, they can provide enhanced electrical, thermal and mechanical characteristics. The emerging field of sensing technologies has witnessed remarkable advancements, resulting from the integration of carbon-based nanocomposites. This paper presents a comprehensive review of the latest developments in key carbon-based nanocomposite sensors. First, the unique properties of carbon nanomaterials are reviewed covering the full dimensional spectrum, followed by main synthesis routes addressing critical aspects such as morphology, surface functionalization, and doping strategies. Later, the synergistic effects arising from the combination of carbon nanomaterials with other components, such as polymers, are explored in detail, emphasizing the role of percolation levels in the overall sensing performance. The different sensing applications presented in this review cover a broad range, including strain, temperature, gas and biosensing. The mechanisms and principles governing the sensing capabilities of carbon-based nanocomposites are provided, shedding light on the interactions between analytes and nanocomposite surfaces. A critical analysis of current challenges and prospects is also presented, outlining potential avenues for further research and innovation. Finally, this review aims to serve as a valuable resource for researchers interested in carbon-based nanocomposites and their evolving role in advancing sensing technologies.

Impact of geopolymer aggregate on the mechanical properties and durability characteristics of concrete

This study examined the use of geopolymer aggregate (GPA), produced from slag and an alkaline solution, as a substitute for coarse aggregate in conventional concrete. The research aimed to evaluate how different proportions of GPA (25%, 50%, 75%, and 100% replacement) affect the durability and mechanical properties of concrete. A series of tests were conducted, including slump, compressive strength, flexural strength, chloride resistance, sulfate resistance, sorptivity, and water absorption. The results demonstrated significant improvements in concrete properties with the inclusion of GPA. The compressive strength of GPA concrete ranged from 31 to 38 MPa, showing a 10%–15% increase over that of standard concrete. Flexural strength improved by 6% at 7 days and 7.5% at 28 days compared to control mixes. Water absorption was reduced by 42.58%, and sorptivity decreased by 47.9% compared to ordinary aggregate concrete. GPA concrete also excelled in acid resistance, with a weight loss of 28.6% and a lower reduction in strength compared to traditional acidic aggregates. In sulfate resistance tests, GPA concrete showed a 31% reduction in both weight and strength loss. These results highlight the advantages of using GPA as an alternative to conventional coarse aggregates. GPA not only enhances the mechanical and durability properties of concrete but also presents a more sustainable option, contributing to reduced environmental impacts associated with traditional aggregate materials.

A Finite Element Analysis of Peri-implant Stresses Surrounding Zirconium and Titanium Dental Implants

ABSTRACT Introduction: Stresses tend to vary depending on the kind of implant material (titanium or zirconium) because of differences in their mechanical and physical characteristics. Objectives: The current research was done to assess the peri-implant stresses around zirconium and titanium dental implants using finite element analysis. Materials and Method: Three distinct implant configurations were used to create three-dimensional finite element models (M1, M2, and M3) using ANSYS (11.0 Version) software, a P4 CPU running at 3 GHz, and hardware with three gigabytes of RAM. These configurations are typical for zirconium and titanium implants. Under 250 N of axial force and 50 N of nonaxial load, the stress surrounding the implants was examined. Result: When compared to titanium implants, zirconium implants displayed higher strains in cancellous bone and lower stresses in cortical bone. Overall, titanium implants caused larger stresses in the bone than zirconium implants. Conclusion: Compared to titanium implants, zirconium implants resulted in reduced peri-implant stresses.

Mechanical and dynamic characteristics for the CFRP, GFRP, and hybrid composites exposed to HCl environment

In the current study, the low-velocity impact (LVI) characteristics of carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), and hybrid composites before and after the corrosive environment exposure were investigated. In this regard, CFRP, GFRP, and hybrid composites were subjected to LVI and tensile loadings after being kept in a 10% diluted HCl environment for 1 week and 1 month, and the impacts of the corrosive environment on the composites’ dynamic and mechanical responses were determined by comparing the outcomes of the control and aged specimens. LVI tests for CFRP, GFRP, and hybrid composites were carried out by transferring 25.2 and 11.2 J impact energy to the specimens with two impact velocities of 3 and 2 m/s, respectively, and thus, the effects of impact energy and hybridization were investigated. Moreover, tensile tests were conducted for the control and aged specimens with 2 mm/min crosshead speed, and thus, the effects of fiber material, hybridization, and corrosive environment on the mechanical properties were determined. The study found that CFRP composites had higher stiffness than GFRPs, whereas hybrid composites exhibited dynamic responses between CFRP and GFRP, as expected. On the other hand, it turned out that the composites absorbed most of the impact energy, which was interpreted as being absorbed by the damage of fiber-reinforced composites, which stand out with their brittle characteristics. Furthermore, it was discovered that the damage severity elevated as expected with a longer aging time, which was attributed to the corrosive liquid attacking the fibers, matrix, and fiber/matrix interfaces and reducing strength. It was also observed that, as predicted, the corrosive effects generally resulted in a reduction in tensile responses, including ultimate strain and tensile strength.

In vitro bioprinted 3D model enhancing osteoblast-to-osteocyte differentiation

In vitrobone models are pivotal for understanding tissue behavior and cellular responses, particularly in unravelling certain pathologies' mechanisms and assessing the impact of new therapeutic interventions. A desirablein vitrobone model should incorporate primary human cells within a 3D environment that mimics the mechanical properties characteristics of osteoid and faithfully replicate all stages of osteogenic differentiation from osteoblasts to osteocytes. However, to date, no bio-printed model using primary osteoblasts has demonstrated the expression of osteocytic protein markers. This study aimed to develop bio-printedin vitromodel that accurately captures the differentiation process of human primary osteoblasts into osteocytes. Given the considerable impact of hydrogel stiffness and relaxation behavior on osteoblast activity, we employed three distinct cross-linking solutions to fabricate hydrogels. These hydrogels were designed to exhibit either similar elastic behavior with different elastic moduli, or similar elastic moduli with varying relaxation behavior. These hydrogels, composed of gelatin (5% w/v), alginate (1%w/v) and fibrinogen (2%w/v), were designed to be compatible with micro-extrusion bioprinting and proliferative. The modulation of their biomechanical properties, including stiffness and viscoelastic behavior, was achieved by applying various concentrations of cross-linkers targeting both gelatin covalent bonding (transglutaminase) and alginate chains' ionic cross-linking (calcium). Among the conditions tested, the hydrogel with a low elastic modulus of 8 kPa and a viscoelastic behavior over time exhibited promising outcomes regarding osteoblast-to-osteocyte differentiation. The cessation of cell proliferation coincided with a significant increase in alkaline phosphatase activity, the development of dendrites, and the expression of the osteocyte marker PHEX. Within this hydrogel, cells actively influenced their environment, as evidenced by hydrogel contraction and the secretion of collagen I. This bio-printed model, demonstrating primary human osteoblasts expressing an osteocyte-specific protein, marks a significant achievement. We envision its substantial utility in advancing research on bone pathologies, including osteoporosis and bone tumors.

Edge dislocations, alloy composition, and grain boundaries effects on the mechanical properties in NiCo binary alloy.

In this research, we investigated the mechanical properties of NiCo binary alloy both with and without grain boundaries, across various alloy compositions. We investigated the effects of edge dislocation, alloy compositions, and grain boundaries on the mechanical properties of FCC using molecular dynamics (MD) simulations. By analyzing the influence of the grain boundaries with different alloy compositions on several mechanical properties, we were able to gain a deeper understanding of how these characteristics were modified. The elastic moduli increased with increasing grain boundaries for a specific chemical composition, indicating that becomes more rigid. The anisotropy factor analysis showed that have a natural tendency toward anisotropy, which is further influenced by the presence of grain boundaries. Grain boundaries have a significant effect on strength and ductility across a wide range of alloy compositions. These results indicate that a deeper comprehension of these implications can aid in designing improved binary alloy with superior mechanical characteristics.

Assessment of the Hardness of Various Orthodontic Wires

ABSTRACT Introduction: The mechanical characteristics of orthodontic wires are crucial since they have a significant impact on the effectiveness of orthodontic therapy, and patients undergoing orthodontic treatment are becoming more and more picky about their aesthetic preferences. Objectives: The goal of the current investigation was to assess the hardness of various orthodontic wires. Materials and Methods: Three types of wires were employed in this study: nickel titanium (NiTi, USA), beta-titanium (TMA, USA), and stainless steel (SS, Germany). For the upper left canine in this investigation, we utilized an edgewise bracket with a slot size of 0.018″. Epoxy resin was used to implant the wires. The orientation of the brackets was horizontal. Next, a measurement was taken of the brackets’ external surfaces’ hardness. Using an optical microscope, the micrographs of the typical Vickers indentations were captured. The acquired data was assessed statistically. Results: The specimens belonging to the stainless steel, nickel-titanium, and beta-titanium groups had mean microhardness values of 523.24, 367.22, and 321.36, respectively. There were noteworthy outcomes when comparing the three research groups. Conclusion: Among the stainless steel group specimens, the highest microhardness was observed. However, more research is advised.

Development and Characterization of Mikania, Kapok, Wool, Sugarcane, and Pineapple Fiber Reinforced Polyester Composite

ABSTRACTThis study utilizes plant‐derived fibers including Mikania, wool, kapok, sugarcane, and pineapple as strengthening additions to fabricated and tested reinforced polyester mixtures. This study aimed to examine the mechanical qualities and potential applications of these natural materials in boosting the effectiveness of polyester composites. The composites were formed by including natural fibers into a polyester base using a hand lay‐up preparation method. The finished samples received a complete assessment, covering tensile and impact testing as well as SEM analysis. The findings showed that incorporating natural materials like Mikania vines, wool, kapok fuzz, sugarcane fibers, and pineapple leaves had a notably positive effect on the mechanical features of the plastic composites. The tensile strength of the material combined pineapple was particularly high, achieving a maximum stress of 42.4822 N/mm2 and a maximum stretch of 4.27950%. Similarly, that same composite exhibited a maximum stretch of 3.75753% and a maximum stress of 77.4922 N/mm2 during the bending experiment. The substances exhibiting the strongest impact endurance, as determined by the impact assessment, included kapok, Mikania, wool, pineapple, and sugarcane. The kapok provided an impact toughness of 1.2 N m, which was somewhat elevated. This research offers a precious understanding of using natural fibers as strengthening additives in polyester composites, demonstrating their flexible perspective for many uses. The discoveries present hopeful possibilities for additional examination and progression in composite materials, consequently advancing the development of sustainable materials.

The Effect of Kappa Carrageenan Composition on the Characteristics of Chitosan-Kappa Carrageenan Hydrogel Film

Chitosan-Kappa Carrageenan (Chit-KC) hydrogel films have been made using a casting method with different compositions. This research aimed to investigate the effects of different compositions on the chemical, physical, and mechanical characteristics of the Chit-KC hydrogel films. The compositions of the kappa carrageenan in the Chit-KC films were 0%, 16.67%, 33.33%, 50.0%, and 100.0%. The films were characterized using FTIR, SEM, DTA-TGA, and XRD instruments to analyze their functional groups, morphology, thermal properties, and crystallinity. They were also tested for their solubility, swelling, water vapor permeability (WVP), and mechanical characteristics. The results revealed that the addition of kappa-carrageenan induced the formation of a polyelectrolyte complex. The polyelectrolyte complex caused an increase in swelling, crystallinity, and WVP values and a decrease in solubility, tensile strength, elongation, and elasticity. It also caused the formation of film layers and granules on the surface of the hydrogel film. The IR spectra exhibited that the Chit-KC hydrogel films contained O-H, C-H, C=O, S=O, C-O, and C-O-C groups. The DTA-TGA test results revealed that the film began decomposing at around 200°C and re-decomposing at 300°C.