Torsional Properties Research Articles

Torsion properties of modified diagonal classes on triple products of modular curves

AbstractConsider three normalized cuspidal eigenforms of weight $2$ and prime level p. Under the assumption that the global root number of the associated triple product L-function is $+1$ , we prove that the complex Abel–Jacobi image of the modified diagonal cycle of Gross–Kudla–Schoen on the triple product of the modular curve $X_0(p)$ is torsion in the corresponding Hecke isotypic component of the Griffiths intermediate Jacobian. The same result holds with the complex Abel–Jacobi map replaced by its étale counterpart. As an application, we deduce torsion properties of Chow–Heegner points associated with modified diagonal cycles on elliptic curves of prime conductor with split multiplicative reduction. The approach also works in the case of composite square-free level.

Investigation of torsional properties of surface- and strut-based lattice structures manufactured using multiJet fusion technology

Investigation of torsional properties of surface- and strut-based lattice structures manufactured using multiJet fusion technology

Abnormal precipitation behaviour of α″-martensite from α-phase under tension–torsion deformation

ABSTRACT The tension–torsion properties and deformation microstructure of near β titanium alloy after various heat treatment have been investigated by transmission electron microscopy (TEM). The samples after aging treatment at 500°C for 8 h possesses obviously higher strength than those samples undergoing other different treatment on account of thin α” plates distributing uniformly in the β grains. Interestingly, precipitation of α″-martensite in α plates were observed for the first time under tension–torsion deformation. The abnormal precipitation behaviour was attributed mainly to the large tensile-shear stress.

Comparative evaluation of bending property and torsional resistance of three nickel–titanium files: A finite element analysis

Aims: We aimed to investigate the effect of instrument length on the torsional resistance and bending property of three nickel–titanium files, namely ProTaper Gold (PTG), ProTaper Next (PTN), and HyFlex CM (HCM) using finite element analysis.Materials and Methods: Three-dimensional models of each aforementioned system were created using the computer-assisted design (CAD) software SolidWorks® 2016 (Dassault Systèmes, SolidWorks Corp., Concord, MA, U. S.). Then, all models were imported to the ANSYS® Workbench 16 (Canonsburg, PA, U. S.) where the simulation was computed. The boundary conditions used to simulate the behavior of the endodontic instruments were in compliance with the ISO 3630 1 specification standards.Results: It was observed that in bending test, HCM model exhibited load of 510.35 MPa with displacement of 6.05 mm, followed by PTG model (465.48 MPa) and 11.21 mm displacement, then PTN file model (440.74 MPa) and 10.30 mm displacement, whereas in torsional test the rigidity curve for HCM file (1.9673 N mm/Radian) lies much below PTG (6.4615 N mm/Radian) which clearly shows that HCM is flexible as compared to PTG and PTN.Conclusion: Considering the high flexibility of the HCM file, it can be effectively used in severely curved root canals and PTG and PTN files in moderately curved root canals. It was also recommended that HCM files should not be kept in canals for a longer time because stresses might reach to ultimate level quickly which can cause fracture.

Angular Optical Trapping to Directly Measure DNA Torsional Mechanics.

Angular optical trapping (AOT) is a powerful technique that permits direct angular manipulation of a trapped particle with simultaneous measurement of torque and rotation, while also retaining the capabilities of position and force detection. This technique provides unique approaches to investigate the torsional properties of nucleic acids and DNA-protein complexes, as well as impacts of torsional stress on fundamental biological processes, such as transcription and replication. Here we describe the principle, construction, and calibration of the AOT in detail and provide a guide to the performance of single-molecule torque measurements on DNA molecules. We include the constant-force method and, notably, a new constant-extension method that enables measurement of the twist persistence length of both extended DNA, under an extremely low force, and plectonemic DNA. This chapter can assist in the implementation and application of this technique for general researchers in the single-molecule field.

Torsional behavior of steel reinforced concrete beam with welded studs: Experimental investigation

This paper totally reports the results of eight pure torsion tests on steel reinforced concrete (SRC) beams and one pure torsion test on contrast reinforced concrete (RC) beam. Test variables included stud position, stud spacing, stud length, stud diameter and stud layout. The test results indicated that the failure pattern of all SRC beams was the ductile failure with the characteristics of multiple 45° inclined cracks and concrete crushing, but for RC beam, that is the brittle failure with single 45° inclined crack. The arrangement of studs at the wed could improve the torsional behavior of SRC beams, and increasing the stud diameter and stud length could play an enhanced effect, but the effect of setting studs at the flange was not significant. Compared with the specimen with symmetrical welded studs, the specimen with staggered welded studs had better torsional properties. Moreover, the stud spacing structured in 150–250 mm was beneficial to the torsional behavior of SRC beams. Considering the positive effect of studs on torsional behavior of SRC beams, the calculation methods of cracking and ultimate torsional moment were proposed, and the calculated value reflected the measured data well.

Seismic behavior of steel reinforced concrete column with welded studs subjected to combined action of compression-bending-shear-torsion

This paper presents the seismic behavior of steel reinforced concrete (SRC) column with welded studs. Nine SRC columns, varying in stud position, stud spacing, stud length and stud layout, were tested under combined compression-bending-shear-torsion cyclic load. All specimens were subjected to bending-torsion failure with the characteristics of concrete crushing and X-shaped cracks. The fullness of hysteretic curves of bending moment and torsion moment showed that the torsional energy dissipation of the SRC columns was poor. The arrangement of studs at the flange could improve the seismic behavior of SRC columns, and decreasing the stud spacing and increasing the stud length could play an enhanced effect, but the effect of setting the studs at the web was not significant. For SRC columns subjected to torsion moment, a certain number of structural studs need to be added to enhance their torsional properties under the condition that the studs can resist bending moment. In addition, the strain distribution illustrated that the web of encased steel played a great role in resisting torsion, so the torsional bearing capacity of SRC columns was mainly controlled by the strength of the web. Based on the unified strength equation established in this paper, a calculation method of torsional bearing capacity of SRC columns, subjected to combined action of compression-bending-hear-torsion, was proposed.

Strength and fracture mechanism during torsion of ultrafine-grained austenitic steel for medical applications

The article considers evaluation of torsional strength and fracture of austenitic corrosion-resistant steel 08Kh18N9 with an ultrafine-grained (UFG) and coarse-grained (CG) structure, widely used in medicine for the production of plates, screws, rods for bone osteosynthesis and other medical products. The structure of the CG steel was studied using an Axiovert 40 MAT metallographic microscope, and the fine structure of the UFG steel was investigated with a JEM-2100 transmission electron microscope. Torsion tests of the cylindrical samples with a diameter of 10 mm were carried out at a temperature of 20 °C on MK-50 installation. JEOL JCM-6000 scanning electron microscope was used for the microfractographic studies of fracture surfaces. The analysis of the “Torque - torsion angle” diagrams showed that the torsional ultimate strength (τt) and yield strength (τ0.3) of UFG steel increase by 1.3 - 3.8 times, and the relative shear (g) decreases by 2.4 times in comparison with CG steel. High values of torsional strength properties of UFG steel make it possible to provide high torque without destroying the product. Consequently UFG steel 08Kh18N9 in comparison with CG steel is a more promising material for the manufacture of medical screws and other medical products that experience significant loads during the torsion process. Three areas were identified on the surface of all fractures: fibrous central part, transitional (middle) part, and a relatively smooth peripheral part. Fracture begins with the formation of shear pits in the middle and peripheral parts, which, with further rotation of the sample, are completely rubbed out (in case CG steel), or remain (in case of UFG steel). Final failure occurs under the action of normal stresses in the central part of the sample.

Strength and Fracture Mechanism during Torsion of Ultrafine-Grained Austenitic Steel for Medical Applications

The article considers evaluation of torsional strength and fracture of austenitic corrosion-resistant steel 08Kh18N9 with an ultrafine-grained (UFG) and coarse-grained (CG) structure, widely used in medicine for the production of plates, screws, rods for bone osteosynthesis and other medical products. The structure of the CG steel was studied using an Axiovert 40 MAT metallographic microscope, and the fine structure of the UFG steel was investigated with a JEM-2100 transmission electron microscope. Torsion tests of the cylindrical samples with a diameter of 10 mm were carried out at a temperature of 20°C on MK-50 installation. JEOL JCM-6000 scanning electron microscope was used for the microfractographic studies of fracture surfaces. The analysis of the torque–torsion angle diagrams showed that the torsional ultimate strength (τt) and yield strength (τ0.3) of UFG steel increase by the factor of 1.3–3.8, and the relative shear (g) decreases by the factor of 2.4 in comparison with CG steel. High values of torsional strength properties of UFG steel make it possible to provide high torque without destroying the product. Consequently, UFG steel 08Kh18N9 in comparison with CG steel is a more promising material for the manufacturing of medical screws and other medical products that experience significant loads during the torsion process. Three areas were identified on the surface of all fractures: fibrous central part, transitional (middle) part, and a relatively smooth peripheral part. Fracture begins with the formation of shear pits in the middle and peripheral parts, which, with further rotation of the sample, are completely rubbed out (in case CG steel), or remain (in case of UFG steel). Final failure occurs under the action of normal stresses in the central part of the sample.

The Effect of Functional Gradient Material Distribution and Patterning on Torsional Properties of Lattice Structures Manufactured Using MultiJet Fusion Technology.

Functionally graded lattice structures have attracted much attention in engineering due to their excellent mechanical performance resulting from their optimized and application-specific properties. These structures are inspired by nature and are important for a lightweight yet efficient and optimal functionality. They have enhanced mechanical properties over the uniform density counterparts because of their graded design, making them preferable for many applications. Several studies were carried out to investigate the mechanical properties of graded density lattice structures subjected to different types of loadings mainly related to tensile, compression, and fatigue responses. In applications related to biomedical, automotive, and aerospace sectors, dynamic bending and rotational stresses are critical load components. Therefore, the study of torsional properties of functionally gradient lattice structures will contribute to a better implementation of lattice structures in several sectors. In this study, several functionally gradient triply periodic minimal surfaces structures and strut-based lattice structures were designed in cylindrical shapes having 40% relative density. The HP Multi Jet Fusion 4200 3D printer was used to fabricate all specimens for the experimental study. A torsional experiment until the failure of each structure was conducted to investigate properties of the lattice structures such as torsional stiffness, energy absorption, and failure characteristics. The results showed that the stiffness and energy absorption of structures can be improved by an effective material distribution that corresponds to the stress concentration due to torsional load. The TPMS based functionally gradient design showed a 35% increase in torsional stiffness and 15% increase in the ultimate shear strength compared to their uniform counterparts. In addition, results also revealed that an effective material distribution affects the failure mechanism of the lattice structures and delays the plastic deformation, increasing their resistance to torsional loads.

A new torsion tester based on an electronic autocollimator for characterizing the torsional behaviors of microfibers.

Torsional properties of single fibers have considerable effects on the performance of fabrics. A new torsion tester with high resolution is developed based on the torsion-balance method and the autocollimation principle for measuring the torsional properties of single fibers. The tester can measure the torque accurately using the torsion wire of known torsional rigidity. The angular displacement of the torsion wire is measured by a non-contact electronic autocollimator. The calibration results show that the maximum torque capability is around 6 × 10-6 N m with a theoretical resolution of about 8 × 10-11 N m. The instrument's validity is verified by comparing the measurement result with that obtained by a torsion pendulum. Torsion tests on four industrially microfibers, including glass fiber, polyimide fiber, carbon fiber, and gold wire, are performed with the tester, which gives shear moduli 71.0 ± 0.4, 5.6 ± 0.1, 22.6 ± 3.1, and 34.3 ± 0.5GPa, respectively. Young's moduli of these fibers are also provided. It is demonstrated that these fibers have a high anisotropy in mechanical properties.

Biomimetic Tendrils by Four Dimensional Printing Bimorph Springs with Torsion and Contraction Properties Based on Bio‐Compatible Graphene/Silk Fibroin and Poly(3‐Hydroxybutyrate‐co‐3‐Hydroxyvalerate)

AbstractTaking inspiration from plant tendril geometry, in this study, 4D bimorph coiled structures with an internal core of graphene nanoplatelets‐modified regenerated silk and an external shell of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) are fabricated by 4D printing. Finite element simulations and experimental tests demonstrate that integrating these biomaterials with different coefficients of thermal expansion results in the temperature induced self‐compression and torsion of the structure. The bimorph spring also exhibits reversible contractive actuation after exposure to water environment that paves its exploitation in regenerative medicine, since core materials also have been proven to be biocompatible. Finally, the authors validate their findings with experimental measurements using such springs for temperature‐mediated lengthening of an artificial intestine.

Tenomodulin and Chondromodulin-1 Are Both Required to Maintain Biomechanical Function and Prevent Intervertebral Disc Degeneration.

The underlying mechanisms and molecular factors influencing intervertebral disc (IVD) homeostasis and degeneration remain clinically relevant. Tenomodulin (Tnmd) and chondromodulin (Chm1) are antiangiogenic transmembrane glycoproteins, with cleavable C-terminus, expressed by IVD cells that are implicated in the onset of degenerative processes. We evaluate the organ-level biomechanical impact of knocking out Tnmd alone, and Tnmd and Chm1, simultaneously. Caudal (c5-8) and lumbar vertebrae (L1-4) of skeletally mature male and female 9-month-old wildtype (WT), Tnmd knockout (Tnmd-/-), and Tnmd/Chm1 double knockout (Tnmd-/-/Chm-/-) mice were used (n = 9-13 per group). Disc height index (DHI), histomorphological changes, and axial, torsional, creep, and failure biomechanical properties were evaluated. Differences were assessed by one-way ANOVA with post hoc Bonferroni-corrected comparisons (P < 0.05). Tnmd-/-/Chm1-/- IVDs displayed increased DHI and histomorphological scores that indicated increased IVD degeneration compared to the WT and Tnmd-/- groups. Double knockout IVDs required significantly less torque and energy to initiate torsional failure. Creep parameters were comparable between all groups, except for the slow time constant, which indicated faster outward fluid flow. Tnmd-/- IVDs lost fluid faster than the WT group, and this effect was amplified in the double knockout IVDs. Knocking out Tnmd and Chm1 affects IVD fluid flow and organ-level biomechanical function and therefore may play a role in contributing to IVD degeneration. Larger effects of the Tnmd and Chm1 double knockout mice compared to the Tnmd single mutant suggest that Chm1 may play a compensatory role in the Tnmd single mutant IVDs.

Прочность и механизм разрушения при кручении технически чистого титана с ультрамелкозернистой структурой

The mechanical behavior and the mechanism of torsional fracture of medical grade titanium Grade4 with an ultrafine-grained (UFG) structure in comparison with a coarse-grained (CG) structure were investigated. CG titanium (dav = 25 μm) was investigated in the hot-rolled state. To obtain the UFG structure, two processing regimes were used. In the first regime, homogenization annealing was carried out at a temperature of 680°C for 1 hour, then equal-channel angular pressing (6 passes) according to the “Conform” scheme (ECAP-С) at a workpiece and tool temperature of 250°C (route Bc, φ =120°). The average grain size is equal to 0.4 μm. In the second regime, after homogenization annealing and six ECAP-C passes, the workpieces were drawn at a temperature of 200°C (ECAP-C+D). The average grain size is equal to 0.2 μm. The torsion test of samples with a diameter of 3 mm (close to the diameter of screws for fixing plates in traumatology) was carried out on a KTS 403‑20‑0.5 installation in accordance with GOST 3565-80. The torque, number of revolutions and angle of twisting of the samples made from CG and UFG titanium, as well as the mechanical properties of titanium during torsion were evaluated. Torsion tests have shown that the torsional strength and the torsional yield strength of UFG titanium increase, and the relative shear decreases in comparison with similar properties of CG titanium. In addition, the mode of nanostructuring (ECAP-C+D) provides higher values of the torsional strength properties of titanium compared to ECAP-C, which is favorable from the standpoint of resistance to fracture of titanium screws by torsion. On the surface of the fractures, there are three regions differing in microrelief: the central part of the fracture, the middle (transitional) and the peripheral parts. In the central part of the fractures, the microrelief consists of equiaxed dimples and structureless areas. In the middle part, shear dimples dominate, and in the peripheral part of fractures, areas of shear dimples alternate with areas of the rubbed surface.

Large Amplitude Motions of Pyruvic Acid (CH3-CO-COOH).

Torsional and rotational spectroscopic properties of pyruvic acid are determined using highly correlated ab initio methods and combining two different theoretical approaches: Second order perturbation theory and a variational procedure in three-dimensions. Four equilibrium geometries of pyruvic acid, Tc, Tt, Ct, and CC, outcome from a search with CCSD(T)-F12. All of them can be classified in the Cs point group. The variational calculations are performed considering the three internal rotation modes responsible for the non-rigidity as independent coordinates. More than 50 torsional energy levels (including torsional subcomponents) are localized in the 406–986 cm−1 region and represent excitations of the ν24 (skeletal torsion) and the ν23 (methyl torsion) modes. The third independent variable, the OH torsion, interacts strongly with ν23. The A1/E splitting of the ground vibrational state has been evaluated to be 0.024 cm−1 as it was expected given the high of the methyl torsional barrier (338 cm−1). A very good agreement with respect to previous experimental data concerning fundamental frequencies (νCAL − νEXP ~ 1 cm−1), and rotational parameters (B0CAL − B0EXP < 5 MHz), is obtained.

Behavior of Cantilever Composite Girder Bridges with CSWs under Eccentric Loading

A study on the torsion and distortion properties of the cantilever single-box three-cell composite girder bridge with corrugated steel webs (CSWs) is carried out based on experimental testing and finite element model analysis. Firstly, the mechanical characteristics such as the deformation, longitudinal warping normal stress were investigated based on a double cantilever girder model test. Secondly, the influence of parameters such as girder height, box width and corrugated steel web thickness on the warping stress of cantilever composite girder with CSWs under eccentric load were analyzed based on the finite element model. Finally, the eccentric load effect of the composite bridge with CSWs at the maximum cantilever construction stage under different load combinations was analyzed based on a finite element model of the real bridge. The results show that the longitudinal warping strain of the CSWs is significantly smaller than that of the top and bottom concrete slabs under eccentric loading due to the accordion effect. The maximum warping normal stress occurs at the corners of the bottom concrete slab. The additional shear stress of the steel webs distributes uniformly along the girder height, and the additional stress of the web on the loading side is clearly greater than that at the middle. The finite element parameter analysis results show that the height and width have a significant influence on the warping stress of single box three-cell composite girder with CSWs, and the thickness of CSWs has almost no effect. In practical engineering, the warping stress of the bottom slab accounts for approximately 20% of the bending stress when the self-weight is considered. Therefore, it is not trivial to consider the influence of the warping normal stress of a concrete slab and the additional shear stress of the CSWs in the design and calculation of this type of bridge.

Torsional Stiffness of Extended and Plectonemic DNA.

DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression. However, direct measurements of these parameters are experimentally challenging. Here, we present a constant-extension method integrated into an angular optical trap to directly measure torque during DNA supercoiling. We measured the twist persistence length of extended DNA to be 22nm under an extremely low force (∼0.02 pN) and the twist persistence length of plectonemic DNA to be 24nm. In addition, we implemented a rigorous data analysis scheme that bridged our measurements with existing theoretical models of DNA torsional behavior. This comprehensive set of torsional parameters demonstrates that at least 20% of DNA supercoiling is partitioned into twist for both extended DNA and plectonemic DNA. This work provides a new experimental methodology, as well as an analytical and interpretational framework, which will enable, expand, and enhance future studies of DNA torsional properties.

Moduli-dependent Calabi-Yau and SU(3)-structure metrics from machine learning

We use machine learning to approximate Calabi-Yau and SU(3)-structure metrics, including for the first time complex structure moduli dependence. Our new methods furthermore improve existing numerical approximations in terms of accuracy and speed. Knowing these metrics has numerous applications, ranging from computations of crucial aspects of the effective field theory of string compactifications such as the canonical normalizations for Yukawa couplings, and the massive string spectrum which plays a crucial role in swampland conjectures, to mirror symmetry and the SYZ conjecture. In the case of SU(3) structure, our machine learning approach allows us to engineer metrics with certain torsion properties. Our methods are demonstrated for Calabi-Yau and SU(3)-structure manifolds based on a one-parameter family of quintic hypersurfaces in ℙ4.

Theoretical analysis on the stiffness of compression–torsion coupling metamaterials

The compression–torsion coupling metamaterials constructed by cells based on chiral mechanism of inclined rods with weak transverse constraints, display superior compression–torsion properties among the metamaterials reported previously. Aiming at metamaterials of this type, a general representative cell is extracted to reveal the relationship between the load and the deformation with considering the compression–torsion coupling effect. The stiffness matrix of the chiral 3D cell is derived based on Euler beam theory and applying dummy-load method, which is expressed as functions of the geometry parameters of cell structures and the mechanical properties of base material. The analytical predictions show good agreement with the numerical simulations. Results show that there exist optimal inclined angles of the rods corresponding to the maximal shear stiffness and the maximal compression–torsion coupling stiffness, respectively, which are both determined by the ratio of circular loop diameter to inclined rod length. This work provides guidelines for the design and analysis of compression–torsion coupling metamaterials, and opens a new avenue for theoretically analyzing the deformation coupling problem.

Effect of fly ash and coupling agent on the structural, morphological, thermal, and mechanical properties of polyamide 6/acrylonitrile‐butadiene‐styrene blend

AbstractIn the present study, coal fly ash (FA) was used as a reinforcement in a thermoplastic matrix blend of polyamide 6/acrylonitrile‐butadiene‐styrene (PA/ABS). In the first part of this work, the as‐received FA (raw FA) was sieved with a 25 μm sieve to obtain FA with particle size less than 25 μm (FA). Then, the physicochemical properties of the raw FA and the FA were determined. Afterwards, FA was used to prepare a masterbatch of 20 wt% FA and 80 wt% PA by twin‐screw extrusion. Using this masterbatch, composites with different FA contents (4.5, 9, 14, and 18.5 wt%), with and without styrene‐(ethylene‐butylene)‐styrene grafted with maleic anhydride (SEBS‐g‐MA) (S‐g‐M), were produced by extrusion, which was followed by injection molding. Subsequently, several characterization techniques were performed to investigate the effect of FA loading and the S‐g‐M coupling agent on the structural, morphological, thermal, and mechanical properties of the developed composites. The results showed that incorporating FA particles in the matrix blend improved the thermal stability and crystallinity, the Young's modulus, the tensile strength, and torsional properties of the composites. In contrast, the addition of S‐g‐M coupling agent to the polymer composites improved the interfacial adhesion between FA particles and the matrix blend. This further enhanced the structural, morphological, thermal, and mechanical properties of the polymer composites. Overall, the use of FA as an inorganic filler improves the thermal and mechanical properties of polymer composites and shows a potential for promising applications.