复杂轮胎钢帘线双尺度结构分析

对全钢载重子午线轮胎钢丝帘线的精确变形和应力分布进行了数值研究。基于子午线轮胎整体建模理论,提出了帘线局部分层建模新方法。结果表明：高伸长率帘线在拉伸仿真中能清楚地观察到结构、弹性及弹塑性变形阶段,而高强度帘线的结构变形阶段不明显;拉弯组合仿真中,单丝均独立弯曲而非统一弯曲,最内层单丝中性轴偏移到压缩区,最外层单丝中性轴几乎仍位于几何对称轴,单丝之间接触面的增大极大地提高了单丝局部压力。最后,实验结果验证了有限元方法的正确性。     

Fault Location Identification for Localized Intermittent Connection Problems on CAN Networks

The intermittent connection（IC）of the field-bus in networked manufacturing systems is a common but hard troubleshooting network problem,which may result in system level failures or safety issues.However,there is no online IC location identification method available to detect and locate the position of the problem.To tackle this problem,a novel model based online fault location identification method for localized IC problem is proposed.First,the error event patterns are identified and classified according to different node sources in each error frame.Then generalized zero inflated Poisson process（GZIP）model for each node is established by using time stamped error event sequence.Finally,the location of the IC fault is determined by testing whether the parameters of the fitted stochastic model is statistically significant or not using the confident intervals of the estimated parameters.To illustrate the proposed method,case studies are conducted on a 3-node controller area network（CAN）test-bed,in which IC induced faults are imposed on a network drop cable using computer controlled on-off switches.The experimental results show the parameters of the GZIP model for the problematic node are statistically significant（larger than 0）,and the patterns of the confident intervals of the estimated parameters are directly linked to the problematic node,which agrees with the experimental setup.The proposed online IC location identification method can successfully identify the location of the drop cable on which IC faults occurs on the CAN network.     

A framework for rapid on-board deterministic estimation of occupant injury risk in motor vehicle crashes with quantitative uncertainty evaluation

Accurate on-board occupant injury risk prediction of motor vehicle crashes(MVCs) can decrease fatality rates by providing critical information timely and improving injury severity triage rates. The present implemented prediction algorithms in vehicle safety systems are probabilistic and rely on multi-variate logistic regression of real-world vehicle collision databases. As a result,they do not utilize important vehicle and occupant features and tend to overgeneralize the solution space. This study presents a framework to address these problems with deterministic and computationally efficient lumped parameter model simulations driven by a database of vehicle crash tests. A 648-case mixed database was generated with finite element and multi-body models and validated under the principal directions of impact with experimental results for a single vehicle body type. Using the finite element database, we developed lumped parameter models for four principal modes of impact(i.e., frontal, rear, near side and far side) with parameters identified via genetic algorithm optimization. To obtain confidence bounds for the injury risk prediction,the parameter uncertainty and model adequacy were evaluated with arbitrary and bootstrapped polynomial chaos expansion. The developed algorithm was able to achieve over triage rates of 17.1% ± 8.5%, whilst keeping the under triage rates below 8% on a finite element-multi body model database of a single vehicle body type. This study demonstrated the feasibility and importance of using low-complexity deterministic models with uncertainty quantification in enhanced occupant injury risk prediction. Further research is required to evaluate the effectiveness of this framework under a wide range of vehicle types. With the flexibility of parameter adjustment and high computational efficiency, the present framework is generic in nature so as to maximize future applicability in improved on-board triage decision making in active safety systems.     

Single lap joints loaded in tension with high strength steel adherends

Single lap joints in many different geometric and material configurations were analysed using finite element analysis and tested in tension. Geometric parameters, such as the overlap length and adherend thickness, together with material parameters such as the adherend and adhesive stress–strain behaviour, were all tested. The mechanisms and modes of failure were observed for different cases, and positions of damage initiation were identified. Failure patterns were related to failure mechanisms. A failure prediction methodology has been proposed and a good correlation was obtained between the experimental and finite element predictions of strength for a variety of joint configurations. The study is presented in two parts. In the first (present paper), high strength steel adherends are considered and in the second paper ductile steel adherends are studied. For high strength steel adherends and a relatively short overlap, failure is dominated by adhesive global yielding. As the overlap gets longer, however, failure is no longer due to global yielding, but due to high local shear strains.     

A generalized Young’s equation for contact angles of droplets on homogeneous and rough substrates

Using Gibbs’ method of dividing surfaces, the contact angle of a drop on a flat homogeneous rough non-deformable solid substrate is investigated. For this system, a new generalized Young’s equation for the contact angle, including the influences of line tension and which valid for any dividing surface between liquid phase and vapor phase is derived. Under some assumptions, this generalized Young’s equation reduces to the Wenzel’s equation or Rosanov’s equation valid for the surface of tension.