Offset Face Research Articles

Nonlinear dynamics of non-orthogonal offset face gear-bearing transmission system

A nonlinear dynamic model of a non-orthogonal offset face gear-bearing transmission system is established, in which nonlinear factors such as input load fluctuation, gear clearance, bearing clearance, and transmission error are considered. The dynamic response of the system is analyzed by solving the differential equation with the numerical method. The subharmonic resonance and primary resonance characteristics of the torsional vibration displacement are analyzed by the multi-scale method. The results show that the change of meshing damping will make the system present rich nonlinear characteristics, and the equivalent static load and meshing damping ratio will affect the resonance characteristics of the system. Choosing the appropriate system parameters can make the system in a stable state and suppress the amplitude of primary resonance and subharmonic resonance.

Design considerations and stress analysis of helical gear drives with unequal and offset face widths

Design considerations and stress analysis of helical gear drives with unequal and offset face widths

Coarse grained modeling of nanostructure and asphaltene aggregation in asphalt binder using dissipative particle dynamics

This study aims to develop coarse grained models of asphalt binders and study nanostructure and aggregation behavior of asphalt binders using Dissipative Particle Dynamics (DPD). The coarse-grained models of asphalt binders with different SARA (asphaltene, aromatic, resin and saturate) fractions were built with the mapping of bead groups and the calculation of forcefield parameters. The simulation results were validated through the calculated molecular structure parameters including interlayer distance and diffusion coefficient of asphaltene. The ordered stacking structures (T shape, face–face, and offset face–face stacking) were observed and the aggregation patterns of asphaltene was more obvious between the same type of asphaltene molecules due to self-similarity. The aggregation rates of asphaltene of three asphalt binders were found positively correlated with the mass fractions of asphaltene, which can be used to better predict relative viscosity of asphalt binders. The colloid structure of coarse-grained asphalt binders was observed on the mesoscale platform with small variations of localized nanostructure in three asphalt models. On the other hand, asphaltene showed the lowest diffusion coefficient that was similar among different asphalt binders. The analysis findings indicated that coarse grained modeling with DPD enables large-size model asphalt systems for observation of morphology and aggregation of asphaltene, providing foundation to study complex molecular interaction in polymer modified asphalt binder.

Towards an understanding of diffusion mechanism of bio-rejuvenators in aged asphalt binder through molecular dynamics simulation

The use of reclaimed asphalt pavement (RAP) is a hot research topic in the field of road engineering, as there are still many issues to overcome so as to become standard engineering applications. The diffusion of virgin/aged asphalt binder is a key process to improve RAP performance. In this study, the asphalt binder diffusion models were developed by molecular dynamics (MD) simulation. Two kinds of bio-rejuvenators (BR-1 and BR-5) were chosen to represent the straight-chain and aromatic structures, respectively. The method of relative concentration, radial distribution function (RDF), and microstructure morphology were used to evaluate the effect of bio-rejuvenators on the diffusion process of virgin/aged asphalt binder. The results showed that bio-rejuvenators had a positive effect on the fusion process between virgin and aged asphalt binder. The volume diffusion coefficient based on asphalt binder diffusion models indicated that the bio-rejuvenators accelerated the fusion process between the virgin and asphalt binder. After adding bio-rejuvenators to the aged asphalt binder, the agglomeration intensity in the SARA fractions was reduced to different degrees. Due to the aging of asphalt binder, asphaltenes formed different types of micro-stacking phenomena such as “T-shaped stacking,” “Face to Face stacking,” and “Offset Face to Face stacking.” The bio-rejuvenators of BR-1 and BR-5 exerted different regenerative effects during the diffusion process of aged asphalt binder. For BR-1, the “Pull-Out” and “Intercalation” effect can be observed in the process of asphaltene deagglomeration. “Pull-Out” is the main regenerative effect of BR-5 in aged asphalt binder. A strong electrostatic interaction occurs between BR-5 and PAHs in asphaltenes. Thus, BR-5 achieves the goal of aged asphalt binder regeneration by attracting PAHs.

Structural and electrochemical properties of two novel CdX2 (X = Br, I) picolinamide complexes

Two novel discrete cadmium(II) complexes, namely [CdBr2(pia)2] (1) and [CdI2(pia)2] (2) were prepared by reactions of aqueous solutions of CdX2 (X = Br, I) salts with picolinamide (pia) in the 2:1 ligand to metal stoichiometric ratio. Both compounds were characterized by elemental analysis, IR-spectroscopy, TG/DSC analyses and electrochemical methods. The electrochemical characteristics of both ligand (pia) and prepared complexes were studied by cyclic and (cyclic) square-wave voltammetry, on a static mercury drop electrode (SMDE), in aqueous media over a wide pH range. The molecular and crystal structure of the compounds was determined by the single crystal X-ray diffraction method. X-ray structure analysis of 1 and 2 have shown that the compounds are isostructural with minor differences in the bond angles of the coordination sphere. In both compounds the Cd(II) ion is coordinated by two halide atoms and two mutually orthogonal picolinamide ligands that act as N,O-chelators in a distorted octahedral arrangement. In the crystal structure, the molecules of 1 and 2 are primarily linked via strong head–to–head amide hydrogen bond interactions forming dimers. In 1 the adjacent dimers are connected via NH⋯Br hydrogen bonds and offset face to face π⋯π interactions that involve pyridine rings, while in the structure of 2, the dimers are connected via CH⋯O, CH⋯N and NH⋯I hydrogen bonds into the final 3D structure. The intermolecular interactions in both crystal structures were further studied by Hirshfeld surface analysis. Electrochemical analysis of 2-picolinamide indicates the irreversible nature of its electro-reduction reaction on SMDE at pH 2. To provide better insight into the redox mechanism and electrokinetic properties of 2-picolinamide, the study of the effect of signal frequency on CSWV response was carried out, too. The electrochemical reduction of complex 2 involves two electron transfer reactions at −0.55 V and −0.83 V, indicating two redox active centers in the molecule, while complex 1 appears to be apparently electro-inactive in the studied potential range.

Grinding Deviation Analysis of Offset Face Gear Based on Involute Disc Wheel

Offset face gear drive has shown many unique advantages in the area of crossed-axes transmission. In this paper, deviation analysis of an offset face gear using a involute disc wheel as a cutting tool has been discussed to achieve precised machining.Firstly, equations of involute disc wheel and offset face gear are derived based on meshing theory.Then, a grinding machine tool is designed and equations of offset face gear containing machining deviation are derived.At last,figures of deviation cloud of face gear surface are created with MATLAB and importance of different machining deviation is discussed.The results show that the deviation Az along the axis of grinding wheel is the most influential deviation,while Ay along the axis of face gear is the least one.

Laser cladding with grinding processing of orthogonal offset face gear

To further develop the advantages of face gear drives and improve their anti-sticking performance and wear resistance, a novel method using laser cladding as the primary process is proposed; here, grinding processing is used as the secondary process, i.e., achieving tooth surface strengthening of the orthogonal offset face gear using two types of materials to form a material gradient based on a laser cladding technology. Then, grinding processing is performed using a five-axis grinding machining. First, according to the forming principle of the face gear tooth surface, we establish the coordinate system of the orthogonal offset face gear and the gear cutter coordinate system; we also derive the tooth surface equation of the virtual gear cutter and the tooth surface equation of the orthogonal offset face gear. Second, we research the principles of the laser cladding and establish a laser cladding test bed for the orthogonal offset face gear. Based on the analysis of the design of the cladding layer and the process parameters of the face gear, the selection of the scanning path, the heat accumulation during the laser cladding process, and the accuracy control of the scanning position, we perform a laser cladding experiment on the offset orthogonal face gear. Third, we establish the machining coordinate system of the face gear based on the machine tool structure and conduct a grinding experiment for the face gear after the cladding process. Finally, we analyze the morphology and hardness of the face gear after grinding. A bench test verification of the axle face gear transmission system is completed. The results show that the precision and surface hardness of the tooth surface are significantly improved after grinding. Meanwhile, the accuracy and feasibility of the laser cladding surface of the face gear are verified.

Interactions of Substituted Nitroaromatics with Model Graphene Systems: Applicability of Hammett Substituent Constants To Predict Binding Energies.

Applicability of Hammett parameters (σm and σp) was tested in extended π-systems in gas phase. Three different model graphene systems, viz. 5,5-graphene (GR), 3-B-5,5-graphene (3BGR), and 3-N-5,5-graphene (3NGR), were designed as extended π-systems, and interactions of various nitrobenzene derivatives (mainly m- and p-substituted together with some multiple substitutions) on such platforms were monitored using density functional theory (M06/cc-pVDZ, M06/cc-pVTZ, M06/sp-aug-cc-pVTZ) and Møller–Plesset second-order perturbation (MP2/cc-pV-DZ) theory. Offset face to face (OSFF) stackings were found to be the favored orientations, and reasonable correlations were found between binding energies (ΔEB) and the ∑|σm| values of the substituted nitrobenzenes. It was proposed previously that |σm| contains information about the substituents’ polarizability and controls electrostatic and dispersion interactions. The combination of ∑|σm| and molar refractivity (as ∑Mr) or change in polarizability (Δα: with respect to benzene) of nitrobenzene derivatives generated statistically significant correlation with respect to ΔEB, thereby supporting the hypothesis related to the validity of |σm| correlations. The |σp| parameters also maintain similar correlations for the various p-substituted nitrobenzene derivatives together with several multiply-substituted nitrobenzene derivatives. The correlation properties in such cases are similar to the |σm| cases, and the energy partition analysis for both the situations reveled importance of electrostatic and dispersion contributions in such interactions. The applicability of Hammett parameters was observed previously on the restricted parallel face to face orientation of benzene···substituted benzene systems, and the present results show that such an idea could be used to predict ΔEB values in OSFF orientations, if the scaffolds are designed in such a way that substituted benzene systems cannot escape their π-clouds.

Tooth Surface Equations of Offset Orthogonal Face Gear and Simulation

Face gear transmission is widely applied for large transmission torque, low vibration and noise, high contact ratio, not sensitive to the axial error and so on. The curved tooth face gear tooth surface geometry is different from the common spur or helical face gear. In this paper, to offset orthogonal curved tooth face gear as the research object, meshing with involute cylindrical worm, studied its tooth surface equations. With MATLAB, SOLIDWORKS and other computer-aided analysis tools, simulating the real tooth surface, drawing the offset orthogonal face gear model respectively.

N-(4-Methoxybenzyl)phthalimide: a triclinic polymorph

The title compound [systematic name: 2-(4-meth­oxy­benz­yl)­isoindoline-1,3-dione], C16H13NO3, represents a triclinic polymorph of the previously reported monoclinic form [Warzecha et al. (2006 ▶). Acta Cryst. E62, o5450–o5452]. The reaction of potassium phthalimide and 4-meth­oxy­benzyl chloride in dimethyl­formamide gave platelet-shaped crystals; these were harvested and then needle-shaped crystals were deposited. The platelet- and needle-shaped crystals correspond to the triclinic and monoclinic forms, respectively. The N—C—Car—Car torsion angles between the ring systems are −82.66 (14) and 95.28 (13)°, resulting in a roof-shaped conformation. In the crystal, mol­ecules are accumulated by offset face–face π–π inter­actions between phthalimide units [centroid–centroid distances = 3.640 (2) and 3.651 (2) Å], with inter­planar distances of 3.321 (1) and 3.435 (1) Å. Weak inter­molecular Car­yl—H⋯O=C and Calk­yl—H⋯O=C contacts form C(8) and C(11) infinite chain motifs, respectively.

Comprehensive studies of non-covalent interactions within four new Cu(ii) supramolecules

This work investigates the supramolecular aggregation of Cu(II) complexes based on a combination of the heterocyclic N-donor ligand 2-aminopyrimidine (2-apym) and a variety of different carboxylate ligands, like salicylic acid (H2SAL), maleic acid (H2MAL), and glycine (HGLY). Four new Cu(II) complexes [Cu(HSAL)2(2-apym)2] (I), [Cu(HSAL)2(2-apym)2]·(H2SAL)2(2-apym) (I′), {(H2-apym)[Cu(GLY)(μ-Cl)2Cl]}n (II) and [Cu(μ-MAL)(2-apym)]n (III) have been synthesized and characterized by elemental analyses, FT-IR spectra, and X-ray structural analyses. I and I′ appear as molecular clusters whereas II is a 1-D coordination polymer with weak axial Cu–Cl interactions. However the last one shows a 2-D coordination polymer with trigonal bipyramidal geometry for Cu(II) ion. The two last cases have no molecular fragments packed with non-covalent interactions. In these new supramolecular compounds, existent species join together with the cooperation of multiple inter/intra-molecular classical O–H⋯O/N, N–H⋯O/N, and non-classical N–H⋯Cl hydrogen bonds (H-bonds), offset face to face π⋯π, edge to face C/N–H⋯π, and lp⋯π stacking interactions in the form of various homo/hetero-synthons leading to architecturally different structures. DFT calculations were used to estimate the binding energy of the involved non-covalent interactions and whole stabilization energy of related network of I, I′, and II. Theoretical calculations facilitate the comparison of intermolecular interactions, which demonstrate that for all of I–II, N–H⋯N and N–H⋯O H-bonds govern the network formation. The equilibrium constants for the three proton-transfer systems including SAL/2-apym, GLY/2-apym, MAL/2-apym, the stoichiometry and stability of complexation of these systems with Cu2+ ion in aqueous solution were investigated by potentiometric pH titration method. The stoichiometries of the most complex species in solution was compared to the crystalline Cu2+ ion complexes with the cited proton-transfer systems.

Effect of Tooth Surface Modification on the Load Sharing and Strength of Offset Face Gear Drive with Spur Involute Pinion

Load sharing is one of the main factors that determine gear strength. In this paper, Tooth Contact Analysis (TCA) and Loaded Tooth Contact Analysis (LTCA) have been performed to investigate the effect of tooth surface modification on the contact ratio, load sharing and strength of an orthogonal offset face gear drive with spur involute pinion. The results indicate that the contact ratio of 2.0 or higher could be achieved. The maximum load carried by single tooth and bending stress are significantly reduced when appropriate tooth surface modification is applied to the orthogonal offset face gear drive.

Dynamic Contact Analysis of the Offset Face Gear

The face gear drive is a gear meshing drive with cylindrical gear and bevel gear. Because of its small space, high contact ratio, large transmission torque, low vibration and noise, not sensitive to the axial phase error of the worm and so on, face gear transmission is widely applied. In the traditional gear transmission dynamic contact analysis (TCA), first, simulate the meshing equation; second, calculate the contact trajectory that is formed by the adherent point; last, solve each of the instantaneous contact areas and solve tooth contact region in meshing process. But it can’t solve the tail, diamond and other high contact defects. In the real mesh transmission, tooth meshing is very complex, including edges contact, multi-tooth engagement and many other issues. With the progress of the times, using finite element analysis software ANSYS, it will be able to simulate the dynamic contact analysis of the gear. In this paper, the offset face gear as the research object, with MATLAB program, Solidworks and ANSYS software, establish the mathematical model of the orthogonal offset face gear, simulate its geometric model in the three-dimensional software. Finally, implement the simulation of its dynamic contact meshing in the finite element analysis software.

Supramolecular assemblies of dimolybdenum transoids built by Mo2-enhanced perfluorophenyl-perfluorophenyl synthons

Two supramolecular assemblies were developed by the dimmolybdenum paddlewheel complex trans-Mo(2)(DAniF)(2)(O(2)CC(6)F(5))(2) (1) (ancillary ligand DAniF = N,N'-di-(p-anisyl)formamidinate) through intermolecular offset face to face C(6)F(5)···C(6)F(5) interactions. The two networks are different because of the presence and absence of tetrahydrofuran (THF) axial coordination to the Mo(2) units, but feature commonly short interplanar distances between the two paired perfluorophenyl groups, that is, 3.30 Å and 3.23 Å, respectively, which are similar to the shortest intermolecular C···F contacts between two atoms in meta and ortho positions. Consistently, as indicated by the Mulliken population analysis, the dipole moments for the meta and ortho C-F bonds are considerably enlarged because the pentafluorobenzoate groups are bonded to the dimetal unit. In comparison, X-ray structural and theoretical analyses were also made for the parent molecule pentafluorobenzoic acid. The resultant data show that charge distribution on the perfluorophenyl group has a major influence on the C(6)F(5)···C(6)F(5) binding mode. Therefore, it is evidenced that the dimetal unit plays a role in further polarizing the highly polarized C-F bonds and the intermolecular perfluorophenyl-perfluorophenyl interactions are dominated by the C···F dipole-dipole interaction, rather than aromatic-aromatic π-π stacking.

Phenyl 4-nitrobenzenesulfonate: Supramolecular Aggregation via $$ {\text{R}}_{4}^{4} $$ (28) and $$ {\text{R}}_{4}^{4} $$ (36) C–H···O Cages

In the crystal structure of the title compound, C12H9NO5S, the dihedral angle between the mean planes of the two aromatic rings is 52.96 (5)°. The supramolecular architecture is dictated by the alternation of $$ {\text{R}}_{4}^{4} $$ (28) and $$ {\text{R}}_{4}^{4} $$ (36) C–H···O cages. Two inversion related phenyl rings form slightly offset face to face π···π interactions. The supramolecular architecture of the title compound, Phenyl 4-nitrobenzenesulfonate is dictated by the alternation of $$ {\text{R}}_{4}^{4} $$ (28) and $$ {\text{R}}_{4}^{4} $$ (36) C–H···O cages. Two inversion related phenyl rings form slightly offset face to face π···π interactions .

The co-crystal of iron(II) complex hydrate with hydroxybenzoic acid: [Fe(Phen)3]Cl(p-hydroxybenzoate).2(p-hydroxybenzoic acid).7H2O

Crystal of [Fe(Phen)3]Cl(PHB).2(PHBH).7H2O (1) is triclinic, space group P-1 with a = 12.0388(11) A, b = 15.5286(14) A, c = 15.7794(14) A, α = 89.759(2)°, β = 75.818(2)°, γ = 71.900(2)° and Z = 2, (phen = phenanthroline, PHBH = p-hydroxybenzoic acid, PHB = p-hydroxybenzoate anion). The phen in adjacent Fe(phen)3 2+ cations are π–π interacted forming offset face to face (OFF) motifs. Juxtaposition of four phen ligands from two cations encapsulate an R2 2(8) dimeric unit of H-bonded PHBH molecules within a centrosymmetric box froming a filled aryl box motif (FAB). Alternation of OFF and FAB motifs form {OFF⋯FAB}∞ strands. The Fe(phen)3 2+ cation engages its phen ligands in π–π and/or CH–π interactions with two crystalographically different PHBH molecules and one PHB anion. Seven water molecules and a chloride anion per iron(II) trisphenanthroline cation fill empty spaces in the structure forming a hydrophilic cluster. Extensive intermolecular H-bond interactions occur between water molecules, chloride anions, PHBH molecules, and PHB anions. Thermal analysis of (1) was done under N2(g). The TG, and dTG curves revealed the expected mass losses. All associated processes are endothermic as shown in the DSC curve.

Co-crystalline hydrogen bonded solids based on the alcohol–carboxylic acid–alcohol supramolecular motif

The helical tubuland diol 4 forms 1∶1 hydrogen bonded co-crystalline adducts with 2-propanol and propanoic acid in space group P21/c, and with benzoic acid in C2/c. In the first of these compounds, the 2-propanol molecules contribute one hydroxy group to the intermolecular O–HO–HO–H hydrogen bond repeat unit. The co-crystals formed with propanoic acid and benzoic acid both contain a O–HOC(R)–O–HO–H repeat unit with the hydrogen bonds surrounding a pseudo-threefold screw axis, and where the carboxylic acid group functions like an extended alcohol hydroxy group. Aromatic offset face–face associations also play a significant role in the crystal structure of the benzoic acid compound.

An oxa-bridged tetrahalo aryl lattice inclusion host

The oxygen-substituted diquinoline tetrabromide 11 has been synthesised and found to be a further example of the tetrahalo aryl inclusion host family. This host forms achiral molecular staircases by means of aromatic offset face–face (OFF) and centrosymmetric pi–halogen dimer (PHD) interactions. The X-ray crystal structures of the compounds (11)2·(chloroform) and (11)2·(dichloromethane) show that the included guest molecules occupy channels between the parallel staircases, and that host inter-staircase O⋯Br association is also significant.

Staircase Inclusion Compounds Formed by Tetrahalodiquinoline Hosts

The tetrabromodiquinoline 2, and its tetraiodo counterpart 3, are members of the new tetrahalo aryl host family. They form lattice inclusion compounds when crystallized from many organic liquids, and the X-ray crystal structures of five such compounds are reported and analyzed in crystal engineering terms. Host molecules assemble into parallel staircases by means of aryl offset face−face and halogen−halogen interactions both within, and between, the staircases. The guests are situated in parallel interstitial channels. Variation of the type of included guest can result in significant changes to the construction and symmetry of the host staircase assemblies.

Interlocking molecular grid lattices involving weak assembly forces

The X-ray structures of the two diquinoline derivatives 6,13-dihydro-6,13-ethano-5,12-diazapentacene (1) and 6α,13α-dibromo-2,9-dichloro-5bα,6,12bα,13-tetrahydropentaleno[1,2-b:4,5-b′]diquinoline (2) reveal that both crystallise by forming network lattices involving only weak intermolecular forces. These very similar lattices contain no aryl edge–edge C–H⋯N R22(8) dimers or efficient aryl offset face–face interactions, commonly found in related diquinoline crystals. Both lattices arise from multiple interlocking, at an inclined angle, of two identical sets of parallel molecular grids. Each grid connector site comprises a centrosymmetric tetramer of molecules held together by weak intermolecular forces, unlike the metal co-ordination motifs normally used to generate grid structures. Edge–edge C–H⋯N weak hydrogen bonds of various types help stabilise these structures by linking molecules of opposite handedness in neighbouring grids.