基于Abaqus的全钢轮胎接地印痕仿真分析

以215/75R22.5和315/70R22.5全钢轮胎为研究对象,通过有限元仿真分析方法模拟轮胎的接地印痕,并量化表征接地印痕形状,将实际测试结果与仿真结果进行了对比。结果表明:行驶面弧度高和胎冠弧半径都对轮胎接地印痕形状产生影响,不同胎冠弧设计方案的轮胎接地印痕形状差异很大;轮胎接地印痕仿真分析精度满足设计需求,可以用于轮胎设计初期的结构优化,有利于提高轮胎性能和节约开发成本。     

165/70R13 79T接地印痕改善

研究165/70R13 79T轮胎外轮廓曲线胎冠第一段弧的弧高h_1设计值不同对轮胎接地印痕的影响。用有限元分析软件对不同设计方案进行模拟计算,结果表明:通过调整轮胎胎冠第一段弧的弧高h_1值,可以改善轮胎接地印痕形状及接地压力分布。     

全钢载重子午线轮胎接地压力分布的仿真研究

以12R22.5全钢载重子午线轮胎为例,利用CAD,Tyabas和Abaqus软件建立有限元分析模型,研究胎冠弧角度、断面宽和零度带束层膨胀率对轮胎接地压力分布的影响。结果表明：随着胎冠弧角度的增大,轮胎接地面积和接地形状矩形因数增大,最大接地压力和平均接地压力减小;随着断面宽的增大,轮胎接地面积和接地形状矩形因数先增大后减小,最大接地压力减小,平均接地压力先减小后增大;零度带束层膨胀率可以控制其附近部位的刚性,从而影响该部位的接地印痕形状,随着零度带束层膨胀率的增大,轮胎接地形状矩形因数先变化不大后减小,最大接地压力和平均接地压力先变化不大后增大。     

子午线轮胎接地特性与胎冠温度场关系的研究

以385/55R22.5载重子午线轮胎为研究对象,采用有限元分析方法研究轮胎内轮廓、仿生胎面弧和带束层结构等对接地特性和胎冠温度场的影响。结果表明:内轮廓与仿生胎面弧设计对胎冠温度影响显著;4层带束层结构的胎冠温度低于"3+0°"带束层结构;平均接地压力、接地面积、硬度因数、接地宽度、接地压力偏度值和印痕面积参数与胎冠温度具有较强的相关性。     

DSP和改性锦纶66帘线在子午线轮胎中的应用对比

以尺寸稳定型聚酯(DSP)和改性锦纶66帘线作为轿车和轻型载重子午线轮胎的胎体骨架材料,对比分析轮胎外缘尺寸和静负荷特性。结果表明,DSP胎体轮胎与改性锦纶66胎体轮胎相比,轮胎静态断面宽小;耐久性试验后,DSP胎体轮胎断面宽变化率小于改性锦纶66胎体轮胎;高速试验后,DSP胎体轮胎断面宽变化率大于改性锦纶66胎体轮胎;一定气压和负荷条件下,DSP胎体轮胎下沉率大,印痕面积小,接地区域单位面积平均压力大,轮胎硬度因数大。DSP胎体轮胎尺寸稳定性好,均匀性好,但操纵性和胎面耐磨性比改性锦纶66胎体轮胎稍差。     

轮胎结构偏差对接地印痕影响的试验和仿真研究

综合利用试验和有限元仿真方法,并引入不对称因子表征轮胎接地印痕的不对称性,研究结构偏差(带束层整体偏移和左右胎肩厚度差异)对轮胎接地印痕的影响。结果表明,结构偏差易造成轮胎接地印痕不对称,其中左右胎肩厚度差异比带束层整体偏移对轮胎接地印痕不对称性的影响更为显著。本研究结果为轮胎生产工艺控制和改善轮胎接地印痕提供了依据。     

VAN系列215/65R16C轮胎设计开发

介绍了VAN系列215/65R16C轮胎设计开发.结构设计:外直径686mm,断面宽221mm,行驶宽度172mm,多段冠弧设计,行驶面弧度高8.1mm,胎圈着合直径401.2mm,胎圈宽度190.5mm,断面水平轴位置(H1/H2)1.05,胎面采用3条纵沟宽对称花纹设计,花纹饱和度为72％～73％.施工设计采用不同...     

载重轮胎轮廓设计与性能的相关性研究

选取12R22.5规格的3个不同品牌载重轮胎,对其轮廓以及接地印痕、静负荷性能和滚动阻力等性能进行分析,研究载重轮胎轮廓设计与性能的关系。结果表明：载重轮胎轮廓设计时,胎面轮廓采用较大的曲率,接地印痕更接近方形,轮胎的刚性更大,静负荷性能提高;肩部曲线采用反弧设计有利于提升轮胎的耐久性能。     

载重子午线轮胎接地特性的有限元分析

采用Abaqus有限元分析软件建立11.00R20载重子午线轮胎与地面接触的三维有限元模型,研究轮胎的接地特性。结果表明:充气压力越高,轮胎接地区域应力出现中心低、边缘高翘曲现象的负荷值越大;下沉量增大,轮胎接地印痕从椭圆变为矩形,高压区由胎冠处移动到胎肩处;在各种工况中,轮胎静态接地面积最大;自由滚动时随着速度提高,轮胎接地印痕纵轴变长、横轴变短,但是接地面积增大,总接地反力也增大;摩擦因数对轮胎的自由滚动半径影响较小,但摩擦因数越大,纵向剪切应力越大,胎面越容易磨损;随着侧偏角增大,接地高压区逐渐向一边移动,接地印痕变为三角形。     

445/65R22.5低断面宽基无内胎全钢载重子午线轮胎的外轮廓设计

介绍445/65R22.5低断面宽基无内胎全钢载重子午线轮胎的外轮廓设计,并应用有限元分析验证和优化胎圈部位曲线的设计。外轮廓设计:外直径1 148 mm,断面宽435 mm,胎圈着合直径569.5 mm,断面高289.25mm,断面水平轴位置(H_1/H_2)0.964,行驶面宽度335 mm,行驶面弧度高10 mm,胎面弧度半径2 018.17 mm。优化设计轮胎的外缘尺寸满足国家标准要求,轮胎性能通过了室内成品试验测试。     

NMR Assessment of Therapeutic Peptides and Proteins: Correlations That Reveal Interactions and Motions

NMR measurements of rotational and translational diffusion are used to characterize the solution behavior of a wide variety of therapeutic proteins and peptides. The timescales of motions sampled in these experiments reveal complicated intrinsic solution behavior such as flexibility, that is central to function, as well as self-interactions, stress-induced conformational changes and other critical attributes that can be discovery and development liabilities. Trends from proton transverse relaxation (R₂) and hydrodynamic radius (R_h) are correlated and used to identify and differentiate intermolecular from intramolecular interactions. In this study, peptide behavior is consistent with complicated multimer self-assembly, while multi-domain protein behavior is dominated by intramolecular interactions. These observations are supplemented by simulations that include effects from slow transient interactions and rapid internal motions. R₂–R_h correlations provide a means to profile protein motions as well as interactions. The approach is completely general and can be applied to therapeutic and target protein characterization.     

195/60R15 88H轿车子午线轮胎的设计简

介绍195/60R15 88H轿车子午线轮胎的设计。结构设计:轮胎外直径614mm,断面宽度212 mm,行驶面宽度160 mm,胎圈着合直径379 mm,胎圈着合宽度178 mm,断面水平轴位置(H1/H2)1.03,胎面采用4条纵向花纹主沟,花纹饱和度63.4%。施工设计:胎面采用三方四块结构,胎体采用1层1670dtex/2尺寸稳定型聚酯帘布,带束层采用2层2+2×0.25HT钢丝帘布和1层930dtex/2锦纶66帘布。采用二次法成型机成型,B型硫化机硫化。成品轮胎强度性能和脱圈阻力达到国家标准要求,耐久性能和高速性能达到企业标准要求。     

Comparison of size distribution data from dynamic light scattering and size-exclusion chromatography

The intensity-defined distribution functions of hydrodynamic radii of equivalent spheres, R_h, obtained from dynamic light-scattering experiments using the CONTIN procedure via the Stokes formula were compared with distributions of gyration radii, R_g, determined by size-exclusion chromatography. The number-, weight-, and intensity- (z)-defined R_g distributions accessible from size-exclusion chromatography experiments were calculated using the Flory-Fox relation. Reliable ratios of average radii, R_g/R_h, for linear polystyrenes having narrow, broad, or bimodal molecular weight distributions were obtained in toluene. Care should be taken to utilize properly averaged experimental quantities. For instance, the CONTIN DLS data evaluation procedure yields the z-average of the inverse of the hydrodynamic radius, 〈1/R_h〉_z^?1. © 1995 John Wiley & Sons, Inc.     

Application of Dynamic and Static Light Scattering for Size and Shape Characterization of Small Extracellular Nanoparticles in Plasma and Ascites of Ovarian Cancer Patients

In parallel to medical treatment of ovarian cancer, methods for the early detection of cancer tumors are being sought. In this contribution, the use of non-invasive static (SLS) and dynamic light scattering (DLS) for the characterization of extracellular nanoparticles (ENPs) in body fluids of advanced serous ovarian cancer (OC) and benign gynecological pathology (BP) patients is demonstrated and critically evaluated. Samples of plasma and ascites (OC patients) or plasma, peritoneal fluid, and peritoneal washing (BP patients) were analyzed. The hydrodynamic radius (R_h) and the radius of gyration (R_g) of ENPs were calculated from the angular dependency of LS intensity for two ENP subpopulations. R_h and R_g of the predominant ENP population of OC patients were in the range 20–30 nm (diameter 40–60 nm). In thawed samples, larger particles (R_h mostly above 100 nm) were detected as well. The shape parameter ρ of both particle populations was around 1, which is typical for spherical particles with mass concentrated on the rim, as in vesicles. The R_h and R_g of ENPs in BP patients were larger than in OC patients, with ρ ≈ 1.1–2, implying a more elongated/distorted shape. These results show that SLS and DLS are promising methods for the analysis of morphological features of ENPs and have the potential to discriminate between OC and BP patients. However, further development of the methodology is required.     

Dependence of intrinsic viscosity and molecular size on molecular weight of partially hydrolyzed polyacrylamide

As a typical water-soluble polymer, ultra-high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (R_g) and hydrodynamic radius (R_h) were less documented due to their high viscosity in aqueous solution. In this work, the molecular structure of five UHMW-HPAM samples with different MW was elucidated by ¹H and ¹³C NMR spectroscopy, and their solution properties were characterized by both static and dynamic light scattering. It is found that all the second virial coefficient (A₂) values are positive and approaching zero, indicating of a good solvent of 0.5 M NaCl for UHMW-HPAM. The weight-average molecular weight (M_w) dependence of molecular size and intrinsic viscosity [η] for these series of HPAM polymers with MW ranging from 4.81 to 15.4 × 10⁶ g·mol⁻¹ can be correlated as R_g = 3.52 × 10⁻²M_w^0.51, R_h = 1.97 × 10⁻²M_w^0.51, and [η] = 6.98 × 10⁻⁴ M_w^0.91, respectively. These results are helpful in understanding the relationship between molecular weight and coil size of HPAM polymers in solution, and offer references for quick estimation of molecular weight and screening of commercial UHMW-HPAM polymers for specific end-users.     

Investigation of polybenzoxazine gelation using laser light scattering

The mechanism of phase growth and gelation due to polymerization of benzoxazine into polybenzoxazine (PBZ) in dimethylsulfoxide and N‐methyl‐2‐pyrrolidone was monitored using laser light scattering. The radius of gyration (R_g) and hydrodynamic radius (R_h) increased gradually with time, confirming nucleation and growth as the mechanism of polymerization‐induced phase separation of PBZ in both the solvents. The experimental data inferred from laser light scattering and scanning electron microscopy established that the PBZ gel networks were formed by spherical building blocks in dimethylsulfoxide and by cylindrical strands in N‐methyl‐2‐pyrrolidone. In the latter case, the cylindrical strands originated from joining of several spheres. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45709.     

Dissolution and enzymatic hydrolysis of casein micelles studied by dynamic light scattering

The effects of temperature, ionic strength, and enzymatic hydrolysis on the average hydrodynamic radius (R _h) of casein micelles in phosphate buffer were studied by using dynamic light scattering. The results showed that the average R _h value of casein micelles decreased irreversibly during the heating, decreased with the increase of ionic strength in lower ionic strength solution (less than 0.05 mol/L), but opposite in higher ionic strength solution (above 0.1 mol/L). The R _h value of casein increased rapidly during the process of enzymatic hydrolysis, and the structural model of casein micelles in the enzymatic hydrolysis process was also proposed, i.e. the casein micelle changed from compact sphere into unfolded and regularly flocky peptides. Translated from The Chinese Journal of Process Engineering, 2006, 6(4), 615–618 [译自: 过程工程学报]     

Influence of Halloysite Nanotube on Properties of Tire Tread Compounds Filled with Silica and Carbon Black Hybrid Filler

Properties of solution styrene butadiene rubber (SSBR), based on passenger car tire tread formulation, filled with silica/carbon black/halloysite nanotube (SiO₂/CB/HNT) hybrid filler were investigated. Effect of HNT was studied by partially replacing CB in the reference compound with 0–16 phr of HNT. With increasing HNT content, mechanical properties such as modulus, hardness, tensile strength, tear strength and abrasion resistance are impaired, due to the combination of low specific surface area of HNT (compared with CB), poor rubber-HNT interaction and poor HNT dispersion. However, the partial replacement of CB with HNT leads to the improvement of wet grip and rolling resistance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46987.     

Determination of molecular weight and molecular sizes of polymers by high temperature gel permeation chromatography with a static and dynamic laser light scattering detector

Flow-mode static and dynamic laser light scattering (SLS/DLS) studies of polymers, including polystyrene, polyethylene, polypropylene and poly(dimethylsiloxane) (PDMS), in 1,2,4-trichlorobenzene (TCB) at 150 °C were performed on a high temperature gel permeation chromatography (GPC) coupled with a SLS/DLS detector. Both absolute molecular weight (M) and molecular sizes (radius of gyration, R_g and hydrodynamic radius, R_h) of polymers eluting from the GPC columns were obtained simultaneously. The conformation of different polymers in TCB at 150 °C were discussed according to the scaling relationships between R_g, R_h and M and the ρ-ratio (ρ=R_g/R_h). Flow-mode DLS results of PDMS were verified by batch-mode DLS study of the same sample. The presented technique was proved to be a convenient and quick method to study the shape and conformation of polymers in solution at high temperature. However, the flow-mode DLS was only applicable for high molecular weight polymers with a higher refractive index increment such as PDMS.     

Mass transfer to percolated porous materials in a small-scale cell operating by self-pumping

The paper deals with an experimental electrochemical study of mass transfer to porous nickel materials (felt, foams) in a small-scale laboratory cell functioning in a self-pumping mode. The liquid flow through a disc of the porous material is induced by the rotation of a solid circular disc. The cell is simple and is useful for laboratory studies of materials for porous electrodes and also for small-scale synthesis using such materials. The work examines separately the mass transfer to the rotating disc and to the porous disc. Empirical correlations of the experimental data are given.Nomenclature a _e specific surface area (per unit of total volume of electrode) (m^–1) - C ₀ entering concentration of ferricyanide ions (mol m^–3) - D molecular diffusion coefficient of ferricyanide (m² s^–1) - e thickness of the sheet of material (m) - F Faraday number (C mol^–1) - g acceleration due to gravity (m s^–2) - h distance between the discs (m) - I _L limiting current (A) - 736-1 mean mass transfer coefficient (m s^–1) - N roating velocity (rev min^–1) - Q _v volumetric electrolyte flow rate (m³ s^–1) - R radius of the solid disc (m) - R _c inner radius of the cell (m) - R _i radius of the porous disc (m) - Re _h Reynolds number based onh (=h²/) - Re _R Reynolds number based onR (=R²/) - S _c Schmidt number - Sh _h Sherwood number based onh (=k _d h/D) - Sh _r Sherwood number based onR (=k _d R/D) - mean electrolyte velocity (m s^–1) - V electrode volume (m³) - X conversion - electrolyte density (kg m^–3) - _e number of electrons in the electrochemical reaction - kinematic viscosity (m² s^–1) - angular velocity (s^–1) - ₀ minimum angular velocity (s^–1)