Root Radius Research Articles

The elasto-plastic numerical study of crack initiation in notched PMMA specimens under uniaxial loading conditions – Tension and torsion

This paper presents the results of FEM numerical calculations aimed at describing the plastic strain and stress fields under critical loading conditions: tensile force or torsional moment. The calculations were carried out with reference to the results of experimental tensile and torsional tests of flat PMMA specimens weakened with V-notches of different root radii: 0.5, 2 and 10 mm. The procedure for conducting nonlinear numerical analyses is described, including the determination of the actual hardening curve by the hybrid method. A high level of consistency between the results of the experimental and numerical calculations was obtained through description of PMMA with the elastic–plastic material model. The points of occurrence of stress maxima and plastic strain were indicated, which were taken as potential crack initiation sites. On the basis of the stress and plastic strain values measured at the critical points, a stress–strain fracture criterion was formulated, which was then positively verified.

Inhibitor screening for volume-sensitive LRRC8A chloride channel

Leucine-rich repeat-containing protein 8 A (LRRC8A) protein is a critical member of volume-regulated anion channels. It plays a critical roles in the regulation of cellular volume and involves in the development of diseases like osteoarthritis. Screening of lead compounds to modulate its function may provide potential therapeutics of related diseases. Here, we employ virtual screening techniques and molecular dynamics (MD) simulation to screen potential inhibitors against LRRC8A. LRRC8A was regarded as the drug target to investigate potential compounds from the ZINC15 database via molecular docking. The final compound was selected among the top 10 Autodock Vina score (–8.8 Kcal/mol) with the ZINC ID ZINC000018195627 after druggability prediction. The docked complex from the virtual screening was subjected to MD simulation to analyze the stability of the LRRC8A protein–ligand complex, with parameters including root mean square deviation, root mean square fluctuation and radius of gyration. Molecular Mechanics/Poisson–Boltzmann Surface Area (MM/PBSA) method was further employed to predict the binding free energies from MD simulation trajectory. Our study provides insightful analysis for the potential compound to modulate LRRC8A and lay the foundation of therapeutics development against osteoarthritis. Communicated by Ramaswamy H. Sarma

Truncated DNM1 variant underlines developmental delay and epileptic encephalopathy.

Developmental and epileptic encephalopathies (DEEs) signify a group of heterogeneous neurodevelopmental disorder associated with early-onset seizures accompanied by developmental delay, hypotonia, mild to severe intellectual disability, and developmental regression. Variants in the DNM1 gene have been associated with autosomal dominant DEE type 31A and autosomal recessive DEE type 31B. In the current study, a consanguineous Pakistani family consisting of a proband (IV-2) was clinically evaluated and genetically analyzed manifesting in severe neurodevelopmental phenotypes. WES followed by Sanger sequencing was performed to identify the disease-causing variant. Furthermore, 3D protein modeling and dynamic simulation of wild-type and mutant proteins along with reverse transcriptase (RT)-based mRNA expression were checked using standard methods. Data analysis of WES revealed a novel homozygous non-sense variant (c.1402G>T; p. Glu468*) in exon 11 of the DNM1 gene that was predicted as pathogenic class I. Variants in the DNM1 gene have been associated with DEE types 31A and B. Different bioinformatics prediction tools and American College of Medical Genetics guidelines were used to verify the identified variant. Sanger sequencing was used to validate the disease-causing variant. Our approach validated the pathogenesis of the variant as a cause of heterogeneous neurodevelopmental disorders. In addition, 3D protein modeling showed that the mutant protein would lose most of the amino acids and might not perform the proper function if the surveillance non-sense-mediated decay mechanism was skipped. Molecular dynamics analysis showed varied trajectories of wild-type and mutant DNM1 proteins in terms of root mean square deviation, root mean square fluctuation and radius of gyration. Similarly, RT-qPCR revealed a substantial reduction of the DNM1 gene in the index patient. Our finding further confirms the association of homozygous, loss-of-function variants in DNM1 associated with DEE type 31B. The study expands the genotypic and phenotypic spectrum of pathogenic DNM1 variants related to DNM1-associated pathogenesis.

The Effects of Undercut Depth and Length on Weldment Mechanical Properties

Undercutting is a fusion welding defect that appears as a groove at the weld metal's toe. An undercut discontinuity forms when welding, particularly when the current is applied at an extremely rapid rate. It decreases the static and fatigue strength of the weld and produces stress concentration at the welding zone. The height of the reinforcement, the weld bead's contact angle, the undercut's breadth, depth, length, and root radius, as well as other factors, affect the stress concentration factor's size. In this study, two mild steel plates with a 20 mm thickness were welded together using gas metal arc welding. Each test plate was machined to have a 30° single bevel groove angle prior to welding. The butt welded plate underwent radiographic NDT testing. A weldment free of defect was created. The weldment was machined into typical test specimens for tensile strength. An undercut defect was simulated by drilling a groove through each tensile test sample. Grooves had different depths and lengths. After that, samples were put through a tensile test. The test findings allowed for the identification of the impacts of groove shape on tensile strength, ductility, and static stress concentration factor.

A Preliminary Geometrical Characterization of Surface Scratches on Aluminium Alloys Used in the Aerospace Industry

Surface marks, such as scratches or cosmetic marks, commonly appear during the manufacturing phase of metallic components, because of the contact between tools and sharp edges with the surface of the parts. Scratches, depending on their width, depth, and root radius, cause a decrease in the fatigue life of metallic alloys. In particular, the presence of scratches with a size comparable to the grain size favors the generation of fatigue cracks in these features. In the aerospace industry, the presence of surface marks is a common cause of rejection. The low hardness of aluminium, a material widely employed in the manufacture of aerospace structures, contributes to the generation of surface marks. In this paper, a preliminary geometrical characterisation of scratches is established. It aims to define a set of parameters to characterise exhaustively the different scratches and to generate different behavior models for each type of scratch. Parameters such as scratch length, path radius, and burr height are considered in addition to the well-known parameters such as scratch depth, root radius, and open angle.

Fatigue limit prediction of cracked and notched specimens related to grain size

Fatigue behavior of specimens is influenced by crack/notch geometry and material properties. Here, a unified fatigue limit model is proposed to describe notch geometry and grain size (G) influences by analyzing fatigue measurements on specimens from 11 kinds of metals (G = 6 to 120 μm) and containing defects (crack, U-notch, sharp and blunt V-notches). Based on Atzori-Lazzarin diagram, fatigue limit of notched specimens (crack is special notch) is linked to notch depth, root radius and opening angle, and the intersections in the diagram are related to G. Additionally, inevitable fatigue-limit scatter is quantified by incorporating normal distribution theory. Results show that proposed model with 96% reliability can predict fatigue limits of different-metal specimens with various defects.

Adsorption and encapsulation of melittin on covalently functionalized carbon nanotubes; a molecular dynamics simulation study

For the first time, molecular dynamics (MD) simulation was used to examine melittin's adsorption and encapsulation on covalently functionalized carbon nanotubes (fCNTs). The CNT wall and terminals were functionalized with carboxy, hydroxyl, and amine functional groups. The findings demonstrated that the melittin would be adsorbed on the fCNT's outer surface when just the CNT terminal is functionalized. On the other hand, melittin is encapsulated inside the nanotube space when the CNTs' walls and terminals are functionalized. Encapsulated melittin has an alpha-helix structure similar to melittin in a water medium. With the use of parameters like root mean square fluctuations (RMSF) and radius of gyration (Rg), the melittin conformational changes were evaluated. According to the findings, the amine functional group significantly alters the melittin's conformation. The wall and terminals fCNTs with hydroxyl and carboxyl could encapsulate melittin inside them with a stable structure. This result will be useful for the design of peptide carriers.

Temperature dependent molecular dynamics simulation study to understand the stabilizing effect of NADES on the protein [formula omitted]-Lactoglobulin

The thermal stability of a protein is an important concern for its practical application in food processing industries. In this study, we have carried out classical molecular dynamics simulations to systematically investigate the effect of NADES (natural deep eutectic solvent) on the stabilization of the protein β-Lactoglobulin (BLG) at different temperatures. This study sheds light on the very aspects of NADES composed of betaine and sorbitol on the stability of the protein. NADES provides better stability to the protein up to a temperature of 400 K than in water. It is observed that the protein starts to unfold above temperature 400 K in spite of the presence of NADES which is quiet evident from the root mean square deviation (RMSD) and radius of gyration (Rg) plots. The decreasing average solvent accessible surface area (SASA) values and increasing intra-protein hydrogen bonds indicate better stability of the protein in NADES medium than in water at temperatures 300 K and 400 K. At high temperatures viz. 450 K and 500 K the number and distribution of solvent species (betaine and sorbitol) around the protein surface show an increment that are evident from the calculations of solvation shell, radial and spatial distribution functions. Increased number of betaine molecules that interact with the protein through electrostatic interaction may lead to destabilization of the protein at these temperatures. This study suggests that NADES could be used as an ideal medium for thermal stability of the protein BLG up to a temperature of 400 K. Beyond this temperature, NADES used for this study fails to exert stabilization effect on the protein.

The allocation of anatomical traits determines the trade-off between fine root resource acquisition-transport function.

Cortex radius (CR) and stele radius (SR) are important functional traits associated with the nutrient acquisition and transport functions of fine roots, respectively. However, for developmental and anatomical reasons, the resource acquisition-transport relationship of fine roots is expected to be different for different root orders. To address this issue, critical fine root anatomical traits were examined for the first three orders of roots of 59 subtropical woody plants. Designating the most distal fine roots as order one, SR scaled isometrically with respect to root radius (RR) (i.e., SR ∝ RR1.0) in the three root orders, whereas CR scaled allometrically with respect to RR (i.e., CR ∝ RR>1.0) with the numerical values of scaling exponents increasing significantly with increasing root orders thereby indicating a disproportional increase in CR with increasing root orders. There were also differences between normalized root tissue (CR/RR and SR/RR) and RR in different root orders. A negative isometric relationship (i.e., SR/RR ∝ RR-1.0) existed between SR/RR and RR in three order roots, whereas the allometric exponent between CR/RR and RR increased with root order (from 0.88 to 1.55). Collectively, the data indicate that root anatomical and functional traits change as a function of RR and that these changes need to be considered when modeling fine root resource acquisition-transport functions.

Comparative biological activity of abamectin formulations on root-knot nematodes (Meloidogyne spp.) infecting cucumber plants: in vivo and in vitro

The root-knot nematodes (Meloidogyne spp.) are considered one of the most destructive diseases in the world. In Egypt, farmers primarily rely on chemical nematicides, which have become costly to control. Currently, abamectin is a bio-based pesticide used as an alternative tool against Meloidogyne spp. on cucumber plants (Cucumis sativus L.). During the current research, four tested abamectin formulations were DIVA (1.8% EW), RIOMECTIN (5% ME), AGRIMEC GOLD (8.4% SC) and ZORO (3.6% EC) compared with two reference nematicides namely, CROP NEMA (5% CS) and TERVIGO (2% SC). The main results showed that, in vitro study elucidated that the most effective formulations of abamectin as a larvicidal were EW with LC50 value of 21.66 µg ml−1. However, in the egg hatching test, the formulations of abamectin SC (2%) and EW were the most effective in reducing egg hatching, with LC50 values of 12.83 and 13.57 µg ml−1. The calculated relative potency values showed diversity depending on the two referenced nematicides. On the other hand, in vivo study, the results indicated that, all tested formulations of abamectin recorded general mean reductions in root galls (23.05–75.23%), egg masses (14.46–65.63%). Moreover, the total population density declined by 39.24–87.08%. Furthermore, the influence of abamectin formulations, in the presence of root-knot nematodes, on the growth of cucumber plants parameters, such as root dry weight, root length, root radius, root surface area, shoot dry weight and shoot height, as well as the content of macro-elements (N, P and K) exhibited varying levels of response.

Failure criterion for brittle materials with U‐notches: Unification of characteristic length‐based and grain size‐based criteria

AbstractHere, the limitations of characteristic length‐based (Lchb) and grain size‐based (Gb) criteria with two or three parameters were pointed out employing the apparent toughness tests of 12 different ceramics at a large span range of U‐notch root radius (ρ) values. After comprehensively considering the potential influencing factors of stress intensity factor (Kc), ρ divided by critical notch tip radius (ρc) was proposed as the independent variable, and the data of 21 materials (covering ceramics, plastics, resins, rocks, and metals) was summarized and discussed to establish a simple and more applicable Kc prediction model. Results indicated that Kc/KIc was a power function of ρ/ρc with a power exponent n of 0.5 for ideal materials and less than 0.5 for actual materials. It was also found that ρc can be calculated simply by KIc2/(πσ02), where σ0 represented the inherent strength. This semiempirical criterion succeeded in unifying the Lchb and Gb criteria without introducing more parameters to increase the prediction accuracy of the Kc at the U‐notch root for brittle materials like ceramics.

Crack propagation life of high-speed aviation gear

The most common fault in aviation power transmission systems is the fatigue fracture of gears, which seriously affects the reliability and safety of the structure. The aim of this study is to analyze the crack propagation path (CPP) to predict the crack propagation life (CPL) of gears. The location of crack initiation is determined by statics analysis and building a gear pair model in ANSYS software. A FEM model of the gear pair with a crack is created, the Stress Intensity Factor (SIF) at the crack tip is calculated, and the influence of the initial state of the crack on the SIF is analyzed. FRANC3D is adopted to obtain the CPP and CPL. Based on the obtained results, the impact of gear structure parameters on CPL is discussed. With the reduction of flange thickness, web thickness, and root radius, the CPL gradually decreases.

Characterising the notch root radii and analyses of stress concentration factors near the dominant valleys of rough surface profiles

Surface roughness is one of the key surface integrity factors affecting the strength and fatigue life of components. Stress concentrations occur due to the randomness of the surface profiles. The presence of a dominant valley, a complex geometry and interacting effects exasperate the severity of the stress concentrations. To estimate the theoretical stress concentration factor (SCF) at the valley, the notch root radius should be estimated carefully. We propose an effective method for estimating the root radius of the deepest valley using numerical derivative techniques. The surface roughness of a carefully sanded Alumec 89 block was measured using SJ-400 tester. The 1-D roughness data was used first to evaluate the root radius of the deepest valleys and then, estimate the SCF using analytical and computational methods. We used 2-D finite element (FE) models under uniaxial tension for the computational analyses. The validity of our method is based on determining the SCF using different theoretical methods and comparing the results to the FE calculations. The theoeritical estimations are made using the Neuber, Inglis and Arola-Ramulu approaches, whereas COMSOL Multiphysics is used for the FE analyses. Comparing the theoeritical methods with the FE calculations, the Arola-Ramulu approach was better, with a maximum of error. The minimum deviations can be explained by the model containing parameters such as , and which are inherent to the roughness profile of the material.

Effects of homogeneous and ultrasonic treatment on casein/phosphatidylcholine complex-emulsions: Stability and bioactivity insights

Casein (CAS), a typical protein emulsifier, has functional properties limited by its chemical structure in practical production applications. This study aimed to combine phosphatidylcholine (PC) and casein to form a stable complex (CAS/PC) and improve its functional properties through physical modification (homogeneous and ultrasonic treatment). To date, few studies have explored the effects of physical modification on the stability and biological activity of CAS/PC. Interface behavior analysis showed that compared to homogeneous treatment, PC addition and ultrasonic treatment could decrease the mean particle size (130.20 ± 3.96 nm) and increase the zeta potential (−40.13 ± 1.12 mV), indicating the emulsion is more stable. The chemical structural analysis of CAS showed that PC addition and ultrasonic treatment promoted changes in its sulfhydryl content and surface hydrophobicity, exposing more free sulfhydryl groups and hydrophobic binding sites, thereby enhancing its solubility and improving the stability of the emulsion. Additionally, storage stability analysis revealed that the incorporation of PC with ultrasonic treatment could improve the root mean square deviation value and radius of gyration value of CAS. These modifications resulted in an increase the binding free energy between CAS and PC (−238.786 kJ/mol) at 50 °C, leading to an improvement in the thermal stability of the system. Furthermore, digestive behavior analysis indicated that PC addition and ultrasonic treatment could increase the total FFA release from 667.44 ± 22.33 μmol to 1250.33 ± 21.56 μmol. In conclusion, the study underscores the effectiveness of PC addition and ultrasonic treatment in enhancing the stability and bioactivity of CAS, offering novel ideas for designing stable and healthy emulsifiers.

Creep damage in 9-12% Cr steel notched components: Microstructural evolution and stress state dependence

To understand the stress state dependent creep damage, following creep tests in 9–12% Cr steel notched components with different root radii, a study of associated time dependent microstructural evolution is presented in this work. Particular attention is paid to the dependence of creep damage evolution on the stress state. The average creep strain of notched component exhibits a typical three-stage characteristic (transient, steady and tertiary stages). During the transient stage, remarkable re-distribution in stress state (equivalent stress and stress triaxiality) is found. The rapid relaxation of equivalent stress near the notch root, associated with the initial coarsening of substructure would delay the nucleation or growth of cavity. By contrast, the time-dependent increase of equivalent stress combined with the relatively high stress triaxiality seems to be responsible for the higher cavity density at the center of notched component. The precipitate coarsening is heterogeneous and promoted by the high level of equivalent stress or stress triaxiality. During the steady stage, the creep damage behavior is related to the magnitude of stress state. Higher cavity density and greater reduction in hardness are mainly found in the region where both the equivalent stress and stress triaxiality are high. As a whole, both the redistribution process of stress states and their levels exhibit significant influence on microstructural evolution and creep damage behavior of notched components at elevated temperatures.

Investigation on Flexural Fracture Behaviour of Bolted Spherical Joints with Crack Propagation in Screw Threads.

Bolted spherical joints, due to their prominent merits in installation, have been widely used in modern spatial structures. Despite significant research, there is a lack of understanding of their flexural fracture behaviour, which is important for the catastrophe prevention of the whole structure. Given the recent development to fill this knowledge gap, it is the objective of this paper to experimentally investigate the flexural bending capacity of the overall fracture section featured by a heightened neutral axis and fracture behaviour related to variable crack depth in screw threads. Accordingly, two full-scale bolted spherical joints with different bolt diameters were evaluated under three-point bending. The fracture behaviour of bolted spherical joints is first revealed with respect to typical stress distribution and fracture mode. A new theoretical flexural bending capacity expression for the fracture section with a heightened neutral axis is proposed and validated. A numerical model is then developed to estimate the stress amplification and stress intensity factors related to the crack opening (mode-I) fracture for the screw threads of these joints. The model is validated against the theoretical solutions of the thread-tooth-root model. The maximum stress of the screw thread is shown to take place at the same location as the test bolted sphere, while its magnitude can be greatly reduced with an increased thread root radius and flank angle. Finally, different design variants related to threads that have influences on the SIFs are compared, and the moderate steepness of the flank thread has been found to be efficient in reducing the joint fracture. The research findings could thus be beneficial for further improving the fracture resistance of bolted spherical joints.

ANALYSIS OF STRENGTH OF A FORK OF THE FORKLIFT BY NUMERICAL METHODS

Forklift is an industrial power truck, commonly called forklifts or lift trucks, then usually have two forks the can be trial power truck used forklifting and transport materials. Fork-lifts, to this day, the fork strength of a forklift under load still seems to be one of the biggest issues. Fork’s related structural design and detail have a significant impact on the overall performance and reliability of a forklift. In this work, static analyses of a fork forklift were performed using Finite Element Method, on the free software FreeCAD, a multidisciplinary software application that is the result of a long-term active collaboration between develop-ers and users. Open science hardware is cheaper, easier to maintain, and more accessible to more people. In this paper, by calculating the maximum normal stress of the section, the force situation and allowable stress of the fork are analyzed. The fork is made of structural material is 40Cr steel. The output values of the static study consist in establishing the distri-bution of equivalent unitary stresses (stress state) according to the von Mises criterion. The maximum stress of the structure is 128 MPa, which is does not exceed the allowable. Then in order to enhance the structural strength of the weak part, the measures of gradually in-creasing the fillet radius of the fork root were proposed, and the radius were selected as 35mm and 45mm, the weight of the forklift load was still 0,5t. Numerical experiments have shown that by increasing the radius from 25 to 45 mm, stresses decrease by 1.1...1.15 times, which is consistent with the theory of basic mechanics that stress concentration can easily lead to fatigue failure of the structure. Both numerical calculations and visual analysis showed consistency, with stress concentrations observed at the fork neck, demonstrating the accuracy of the established finite element model.

Selenium Organic Content Prediction in Jengkol (Archidendron pauciflorum) and Its Molecular Interaction with Cardioprotection Receptors PPAR-γ, NF-κB, and PI3K.

Selenium (Se) is a trace mineral found in plants with a distinct sulfuric odor that is cardioprotective and reported to have low toxicity. West Java, Indonesia, has a variety of plants with a distinct odor that are consumed raw, such as jengkol (Archidendron pauciflorum). This study is conducted to determine the Se content of jengkol using the fluorometric method, where the jengkol extract is separated, and the Se content is detected using high-pressure liquid chromatography (HPLC), combined with fluorometry. Two fractions with the highest Se concentration (A and B) are found and characterized using liquid chromatography mass spectrometry to predict the organic Se content by comparing the results with those in the external literature. The Se content of fraction (A) is found to be selenomethionine (m/z 198), gamma glutamyl-methyl-selenocysteine-(GluMetSeCys; m/z 313), and the Se-sulfur (S) conjugate of cysteine-selenoglutathione (m/z 475). Furthermore, these compounds are docked on receptors involved in cardioprotection. The receptors are peroxisome proliferator-activated receptor-γ (PPAR-γ), nuclear factor kappa-B (NF-κB), and phosphoinositide 3-kinase (PI3K/AKT). The interaction of receptor and ligan that has the lowest binding energy of the docking simulation is measured with molecular dynamic simulation. MD is performed to observe bond stability and conformation based on root mean square deviation, root mean square fluctuation, radius gyration, and MM-PBSA parameters. The results of the MD simulation show that the stability of the complex organic Se compounds tested with the receptors is lower than that of the native ligand, while the binding energy is lower than that of the native ligand based on the MM-PSBA parameter. This indicates that the predicted organic Se in jengkol, i.e., gamma-GluMetSeCys to PPAR-γ, gamma-GluMetSeCys AKT/PI3K, and Se-S conjugate of cysteine-selenoglutathione to NF-κB, has the best interaction results and provides a cardioprotection effect, compared to the molecular interaction of the test ligands with the receptors.

Fuzzy set‐based methodology for manufacturing parameter determination of 3D‐printed polylactide components with user‐specified strength, geometrical design, and cost requirements

AbstractA computational data‐driven fuzzy set‐based methodology is proposed and applied to determine, with high accuracy, the manufacturing parameters of 3D‐printed polylactide (PLA) components, ensuring user‐specified failure tensile strength and design requirements (here: the notch root radius). Hence, the novel decision‐making tool to estimate 3D‐printing process parameters is offered, ensuring desired design characteristics and the mechanical performance. The estimated manufacturing angle and infill density have been adjusted to provide meaningful values for real applications, still resulting in accurate predictions through the validation process. Following the success of these design and strength driven estimations, an extension of the proposed methodology to the cost‐saving problem has then been suggested by introducing printing period and material cost as extra inputs to the decision‐making process.

Influence of notch root radius on high cycle fatigue properties and fatigue crack initiation behavior of Ti-55531 alloy with a multilevel lamellar microstructure

Notch high cycle fatigue (HCF) properties and microcrack initiation behavior of Ti-55531 alloy with a multilevel lamellar microstructure under various notch radii were systematically investigated. Results indicate that the reduction of notch root radius significantly promotes fatigue microcrack initiation, and then dramatically reduces the HCF life and strength of the alloy. Cyclic deformation of the alloy is mainly controlled by the slipping and deformation twinning in α plates. The primary fatigue crack initiation micro-mechanism is α/β interface cracking induced by slipping and twinning at all notch HCF specimens. Moreover, the volume fraction of twinning would increase with decreasing of the notch root radius. Interestingly, when the notch root radius is the smallest (R = 0.14 mm) and the stress concentration factor is the largest (Kt = 4), in addition to slipping and twinning, basal stacking faults promoting the cracking of α/β interface could be another crucial HCF microcrack initiation mechanism of the alloy. Furthermore, with decreasing of notch root radius and increasing of stress concentration factor, the size of cycle plastic deformation zone at notch root gradually reduces to the size of α colony and even the α plate. Therefore, the order of influential degree of three different levels microstructure on the crack initiation mechanism of notched HCF can be arranged as α plate > α colony > β GB.