Evaluation Of Strength Research Articles

Analytical model for evaluating bond strength of steel rebar in cracked concrete considering confinement effect

This study delves into the intricate relationship between concrete cracking and bond strength, a critical factor in transferring forces between concrete and steel rebars. While previous research has often overlooked the impact of concrete cracking on bond strength and overestimated the beneficial effects of external confinement, this study aims to fill these gaps. A new failure criterion is introduced to predict bond strength of steel rebar in cracked concrete, considering the influence of concrete crack roughness and steel rebar surface features on force transfer at their interface. This criterion incorporates an interlock capacity coefficient that considers crack kinematics and the mentioned factors, enhancing the evaluation of effective compressive strength of cracked concrete in the limit analysis. Leveraging the Mohr-Coulomb failure criterion, an adaptable failure criterion accounts for crack kinematics, concrete damage, and confinement level to assess force transfer at the concrete/steel rebar interface. The developed criterion offers a practical calculation method to estimate bond strength in cracked reinforced concrete (RC) members with various confinement setups. Validation of this criterion and approach involved comparison against experimental results from 127 specimens, confirming its effectiveness and reliability in predicting bond strength in real-world scenarios.

Wpływ ograniczenia naprężenia na stabilność masy skalnej

A huge number of factors controls rock mass failure, but it is mainly influenced by the state of stress and in particular on the bearing capacity and failure mechanism of the massif. The evaluation of rock mass strength in confined and unconfined compression, as well as its tension strength, are key issues to understand rock mass behaviour prior to failure. A connection between the laboratory analyses of the rock mass and the practical use of the obtained data is presented in the current work. The strength properties, confinement effect and failure mechanisms are successfully studied in volcanic rock specimens from an underground mine. In order to estimate the confinement effect on rock mass strength properties, different confined compression stresses on rock specimens are applied. In addition, the crack initiation and propagation in rock samples are observed and rock mass failure mechanisms are studied. The obtained data is used for stability analyses of an underground openings through determination of the safety factor. The obtained results of the safety factors underlined the influence of the confining stress on the rock mass. The tendency of increasing values of the shear safety factor and decreasing values of the tensile safety factor as confinement increases is found. This is an important observation that would allowed more accurate predictions of the stable and unstable zones of the underground openings to be carried out, and thus the stability of the rock mass to be improved.

Effect of Limb Dominance on Chronic Ankle Instability: Does It Matter?

Our study aimed to examine preoperative differences in strength and balance between dominant foot (DF) and nondominant foot (non-DF) of individuals undergoing ligament stabilization surgery in the general population. Patients with records of preoperative evaluation, including isokinetic dynamometric strength evaluation, Y-balance test (YBT), and Foot and Ankle Outcome Score (FAOS), were included in the study. The DF was the preferred leg for accurately kicking a ball through a goal. Statistical analysis determined the differences between DF and non-DF and the correlations between muscle strength, balance, and FAOS. There was no statistically significant difference between DF and non-DF regarding evertor and invertor muscle strength (p=0.082-0.951). The YBT revealed no significant difference between the two groups (p=0.082-0.951). There was a significant correlation between the evertor peak torque and total work deficits at 30°/s (p=0.022), as well as the evertor peak torque deficit at 120°/s (p=0.048). No significant differences in muscle strength and balance were found between DF and non-DF in nonathletes with chronic ankle instability. Peroneal muscle strength deficit was associated with functional impairment. Tailored interventions are needed to address limb dominance and muscle strength deficits in CAI management.

Revealling pore microstructure impacts on the compressive strength of porous proppant based on finite and discrete element method

Ceramic spheres, typically with a particle diameter of less than 0.8 mm, are frequently utilized as a critical proppant material in hydraulic fracturing for petroleum and natural gas extraction. Porous ceramic spheres with artificial inherent pores are an important type of lightweight proppant, enabling their transport to distant fracture extremities and enhancing fracture conductivity. However, the focus frequently gravitates towards the low-density advantage, often overlooking the pore geometry impacts on compressive strength by traditional strength evaluation. This paper numerically bypasses such limitations by using a combined finite and discrete element method (FDEM) considering experimental results. The mesh size of the model undergoes validation, followed by the calibration of cohesive element parameters via the single particle compression test. The stimulation elucidates that proppants with a smaller pore size (40 µm) manifest crack propagation evolution at a more rapid pace in comparison to their larger-pore counterparts, though the influence of pore diameter on overall strength is subtle. The inception of pores not only alters the trajectory of crack progression but also, with an increase in porosity, leads to a discernible decline in proppant compressive strength. Intriguingly, upon crossing a porosity threshold of 10 %, the decrement in strength becomes more gradual. A denser congregation of pores accelerates crack propagation, undermining proppant robustness, suggesting that under analogous conditions, hollow proppants might not match the strength of their porous counterparts. This exploration elucidates the underlying mechanisms of proppant failure from a microstructural perspective, furnishing pivotal insights that may guide future refinements in the architectural design of porous proppant.

Comparative evaluation of the shear strength of orthodontic adhesives for fixation of brackets

Comparative evaluation of the shear strength of orthodontic adhesives for fixation of brackets

Development and Experimental Verification of Inorganic Electromagnetic Pulse Shielding Paint for Building Interiors Using Carbon-Based Materials.

The term electromagnetic pulse (EMP) generally refers to high-power electromagnetic waves and can be classified into EMPs caused by nuclear weapons, non-nuclear EMPs, and EMPs caused by natural phenomena. EMPs can cause catastrophic damage to any electronic device consisting of electromagnetic components, including communications devices and transportation. In this study, the shielding effectiveness of paint was evaluated depending on the type and content of carbon material and binder. To analyze the compatibility and dispersibility improvement of the raw materials used in paint manufacturing, experiments were conducted in two stages, using 27 mixtures. The shielding effectiveness was evaluated for the optimal mixture developed through mixture experiments. The results of this study confirmed that the developed EMP shielding paint can improve the shielding effectiveness of concrete by 25-40 dB. Additionally, the adhesion strength and moisture resistance evaluation of the EMP shielding paint were evaluated. The average adhesive strength of the EMP shielding paint was 1.26 MPa. In moisture-resistance testing at a temperature of 50 ± 3 °C and a relative humidity of 95% or higher for more than 120 h, no cracks or peeling were observed on the painted surface.

Effect of Cu-Sn-Ti solder alloy on morphology, bonding interface, and mechanical properties of cBN grits

Cubic boron nitride (cBN) grits were joined with a Cu70-Sn20-Ti10 solder alloy powder at a temperature of 960 °C for 20 min under vacuum. The bonding morphology, macroscopically and microscopically, was analyzed, along with the interfacial reaction layer products and thickness of Cu-Sn-Ti/cBN grits. The research extensively characterized the surface morphology and attachment phase of cBN grits both before and after a reaction process. The analysis also included a detailed examination of the cBN grits' morphology. Moreover, the research performed a comparative evaluation of the compressive strength of cBN before and after the reaction, providing valuable insights into the effect of the reaction process on cBN's mechanical properties. The results indicate that the solder effectively wets the surface of the cBN grits, demonstrating good wettability. At the microscopic level,the reaction layer with a structural sequence of cBN-TiB2-TiB-TiN forms at the interface between the two materials. This reaction layer is approximately 5.65 μm thick and exhibits a chemical metallurgical combination. Moreover, the compressive strength of cBN remained unchanged before and after brazing.

Evaluation of the tensile strength and impact property of polyamide/short glass fibre-multi-walled carbon nanotube composites: an experimental study based on response surface method

The tensile strength, impact property and thermal stability of polyamide 6 (PA6) reinforced with carboxylic acid-functionalised multi-walled carbon nanotubes (MWCNTs) with 1 and 2 wt.%, and short glass fibre (SGF) with 10 and 20 wt.%, were investigated. The morphological properties were examined by SEM. The differential scanning calorimetry (DSC) was also carried out to explore the thermal stability and crystallinity of nanocomposites. For determining the optimal weight percentage of reinforcements, the response surface methodology (RSM) was used. The effect of nanotubes and weight percentages of fibre on the tensile and impact properties was investigated by analysis of variance. The results indicated that the incorporation of MWCNTs to PA6 increased the tensile and impact strength of the matrix by 16% and 24%, respectively. Also, the addition of SGFs to polyamide improved the mechanical properties. The results also showed that the nanocomposite containing 1 wt.% MWCNTs and 20 wt.% SGFs had the highest properties (66% increase for tensile and 81% increase for impact strength compared to neat PA6). The DSC results confirmed the effect of reinforcements on thermal characteristics of nanocomposites. The validation of output models of responses implies the ability of models to predict the tensile and impact behaviour of composites.

Strength Evaluation of Expansive Soil Stabilized with Lead–Zinc Mine Tailings and Cement: An Artificial Intelligence Approach

Strength Evaluation of Expansive Soil Stabilized with Lead–Zinc Mine Tailings and Cement: An Artificial Intelligence Approach

Strength Evaluation of CFRP-Strengthened RC Slab-Beams System by Load Test to Satisfy the Safety Requirements: A Case Study

Strength Evaluation of CFRP-Strengthened RC Slab-Beams System by Load Test to Satisfy the Safety Requirements: A Case Study

Ultimate strength of light-rail hybrid cable-stayed bridge including concrete tension softening effect

This paper presents an analysis of the ultimate strength of a light-rail hybrid cable-stayed bridge (CSB) and discusses the influences of the concrete tension softening effect (CTSE), which is defined as the tensile strength of concrete being much less than its compressive strength. Both geometrical and material non-linearities are considered. A finite-element model of the bridge was established using Ansys software, with material non-linearity considered through the fibre beam element Beam189. An algorithm was written using Fortran language for the uniaxial concrete constitutive model to consider the CTSE (i.e. the concrete smeared crack model). The results showed that the CTSE significantly influenced the ultimate strength of the investigated bridge when the side-span concrete girder dominates the failure of the bridge as estimated by calculations. It is essential to consider the CTSE for the evaluation of the ultimate strength of a light-rail hybrid CSB.

Strength Evaluation of Flush End-Plate Connection Using Triangular Haunch in Pipe Rack

Strength Evaluation of Flush End-Plate Connection Using Triangular Haunch in Pipe Rack

An in vitro evaluation of bond strength and failure behavior between 3D-printed cobalt-chromium alloy and different types of denture base resins

ObjectivesThis study aimed to evaluate the shear bond strength and failure behavior between cobalt-chromium (Co-Cr) alloy and different types of denture base resins (DBRs) over time. MethodsSeventy-two disk-shaped specimens (8 mm in diameter and 2 mm in thickness) were manufactured using a selective laser melting technology-based metal 3D printer. Three types of DBRs were used: heat-cure (HEA group), cold-cure (COL group), and 3D-printable (TDP group) DBRs (n = 12 per group). Each DBR specimen was fabricated as a 5 mm × 5 mm × 5 mm cube model. The specimens of the TDP group were manufactured using a digital light processing technology-based 3D printer. Half of the DBRs were stored in distilled water at 37 °C for 24 h, whereas the remaining half underwent thermocycling for 10,000 cycles. Shear bond strength was measured using a universal testing machine; failure modes were observed, and metal surfaces were evaluated using energy dispersive spectrometry. ResultsThe shear bond strength did not differ between the DBR types within the non-thermocycled groups. Contrarily, the TDP group exhibited inferior strength compared to the HEA group (P = 0.008) after thermocycling. All three types of DBRs exhibited a significant decrease in the shear bond strength and an increased tendency toward adhesive failure after thermocycling. ConclusionsThe bond strength between 3D-printable DBRs and Co-Cr alloy was comparable to that of heat-and cold-cure DBRs before thermocycling. However, it exhibited a considerable weakening in comparison to heat-cure DBRs after simulated short-term use. Clinical SignificanceThe application of 3D-printable DBR in metal framework-incorporated removable partial dentures may be feasible during the early phase of the treatment. However, its application is currently limited because the bond strength between the 3D-printable DBR and metal may weaken after short-term use. Further studies on methods to increase the bond strength between these heterogeneous materials are required.

Sustainable Construction with Cattail Fibers in Imbabura, Ecuador: Physical and Mechanical Properties, Research, and Applications

This study is dedicated to advancing practical and experimental knowledge within sustainable construction and enhancing community productivity, focusing on cattail schoenoplectus californicus, Cyperaceae fibers in Imbabura, Ecuador. The research aims to meticulously analyze and understand cattail fibers’ physical and mechanical properties, characteristics, and potential applications through extensive laboratory testing. The study strives to contribute significantly to the ongoing discussions surrounding sustainable building materials by offering a rich repository of scientific data and insights from our in-depth investigations. Furthermore, we delve into biotechnology and biomimicry, seeking inspiration from the natural world to innovate our construction methodologies. Our exploration also encompasses the technical dimensions of a building, artisanal craftsmanship, eco-conscious design principles, and the evaluation of seismic strength within architectural, structural, and acoustical design frameworks. Through this comprehensive approach, we aspire to illuminate new pathways for employing cattail in sustainable construction practices.

Enhancing Index and Strength Properties of Black Cotton Soil Using Eco Friendly Material: GGBS

This research investigates the efficiency of utilizing Ground Granulated Blast Furnace Slag (GGBS) for soil stabilization, aiming to improve index and strength properties and address environmental sustainability through waste utilization. Various laboratory tests, including compaction, Atterberg limits, and unconfined compressive strength evaluations, were conducted on soil samples of Hingoli district amended with GGBS at different ratios. The results reveal significant enhancements in engineering properties, indicating the potential of GGBS in soil stabilization practices. The findings underscore the economic and environmental benefits of incorporating GGBS into soil stabilization techniques, offering a sustainable solution for both soil improvement and waste management in construction projects. This study contributes to the advancement of sustainable engineering practices by demonstrating the effectiveness of waste utilization in enhancing soil performance and mitigating environmental impacts. Keywords-: GGBS, Atterberg Limit, Hingoli, Unconfined Compressive Strengtht, Speicfic Gravity

Evaluation Mechanical Properties of Repaired Polyamide Dentures at Different Processing Techniques and Surface Treatment

Background: Polyamide denture base materials have gained prominence in dentistry due to their superior attributes compared to traditional acrylic materials. However, the susceptibility of polyamide dentures to fractures necessitates exploration of repair, replacement, and reinforcement methods. Effective denture rehabilitation requires enhancing tensile and transverse strength.Methods: This study utilized 160 acrylic resin samples. The control group included 40 specimens with and without fusing material integration, representing fractured and intact scenarios. The remaining 120 specimens underwent meticulous repair through three approaches: Reinjection nylon repair (RiNR), Recycling Manual heating (spruing) repair (RcNHR), and Manual heating nylon (NHR) repair, each with American and Russian fusing materials. Rigorous tensile and transverse strength evaluations were performed. Results: Techniques augmenting tensile and transverse strength (RcNHR, NHR, RiNR) were significantly effective compared to untreated fractures (C2) for both fusing materials. The control group (C1) consistently exhibited higher strength than C2. RiNR exhibited paramount strength, with American-treated RcNHR showing lower tensile strength, and Russian-treated NHR showing reduced transverse strength. Russian and American treatments showed no significant differences in RcNHR and RiNR, but differences emerged in NHR. Conclusion: Implementing flexible materials enhances polyamide denture strength. Reintegration through reinjection and manual heating with sprue-material yielded positive outcomes. RiNR achieved the highest strength. Russian and American treatments showed no notable differences in RcNHR and RiNR, with variations seen in NHR. This study suggests potential for refining mechanical properties and methodologies, advancing denture restoration practices.

Low-carbon UHPC with glass powder and shell powder: Deformation, compressive strength, microstructure and ecological evaluation

Waste glass and shells are by-products generated in the production process of the construction industry and aquaculture respectively. The high-value treatment of these materials presents a global challenge. Converting waste glass and shells into solid waste-based ultra-high performance concrete (UHPC) mixtures is an eco-friendly strategy. In this study, glass powder (GP) and oyster shell powder (OSP) were mixed to prepare composite supplementary cementitious materials (GOS) and partially replace cement. The compressive strength, drying shrinkage, microstructure, and environmental impact of GOS-containing UHPC were investigated. Results indicate that adding GOS reduces the fluidity of UHPC mixtures, with further decreases as GOS content increases. Replacing cement with an appropriate amount of GOS (10 wt%-20 wt%) enhances the compressive strength of UHPC, though higher GOS levels reduce its strength. Meanwhile, the drying shrinkage deformation of UHPC decreases significantly as the GOS substitution level increases. The 28-d drying shrinkage deformation of the specimen added with 20 wt% GOS is 574 μm/m, which is 61.96 % lower than the control group. Additionally, the specimen added with 20 wt% GOS shows significantly improved compactness and enhanced bonding at the interfacial transition zone. Compared with traditional UHPC, GOS-containing UHPC has lower carbon emissions and costs, effectively utilizes waste, and promotes sustainable development.

Development of Strength Evaluation Methodology for Independent IMO TYPE C Tank with LH2 Carriers

Given the inadequate regulatory framework for liquefied hydrogen gas storage tanks on ships and the limitations of the IGC Code, designed for liquefied natural gas, this study introduces a critical assessment procedure to ensure the safety and suitability of such tank designs. This study performed a heat transfer analysis for boil-off gas (BOG) calculations and established separate design load cases to evaluate the yielding and buckling strength. In addition, the study assessed methodologies for both high-cycle and low-cycle fatigue assessments, complemented by comprehensive structural integrity evaluations using finite element analysis. A comprehensive approach was developed to assess the structural integrity of Type C tanks by conducting crack propagation analysis and comparing these results with the IGC Code criteria. The practicality and efficacy of these methods were validated through their application on a 23K-class liquefied hydrogen carrier at the concept design stage. These findings may have important implications for enhancing safety standards and regulatory policies.

Strength Evaluation of Combined New and Old Plates Welded Joint: Case of Anggada XV Tug Boat

Strength Evaluation of Combined New and Old Plates Welded Joint: Case of Anggada XV Tug Boat

Strength Evaluation on Stabilized Sub Grade of MMGSY Road

Strength Evaluation on Stabilized Sub Grade of MMGSY Road