报告人：Tomislav Trisovic教授塞尔维亚科学艺术院技术研究所

邀请人：李伟

报告时间：2022年5月18日-2022年5月19日

腾讯会议ID：502 7594 2895

报告人简介：Tomislav Trisovic教授于2004年在贝尔格莱德大学科技与冶金学院获得博士学位，主要研究电子化学、污水处理等课题。在国际期刊发表重要学术论文二十余篇，获得技术专利19项，是塞尔维亚冶金协会会员。主持10余项国际合作项目，先后获得技术创新奖、金牌勋章等奖励。

报告题目1：STATISTICAL ANALYSIS OF 3D PRINTING PARAMETER EFFECT ON TENSILE PROPERTIES OF FDMpolypropylene material

Abstract：In this research polypropylene specmens were tested with regard to different 3D printing regimes to assess 3D printing effects on its tensile properties. Four batches of specimens were prepared, with five specimens per batch according to tensile testing standard, in the following order: 1) 0.1 mm layer height and 50 % infill density, 2) 0.1 mm layer height, 100 % infill density with rectilinear orientation of printing, 3) 0.1 mm layer height, 100 % infill density with circular orientation of printing and 4) 0.2 mm layer height and 50 % infill density. Experiment data were analyzed using statistical metod ANOVA with Tukey HSD Post Hoc Test. Obtained results showed that printing parameters have significant influence on tensile properties of polypropylene, especially in the case of the layer height, infill density and the printing direction efects on the elastic modulus. Also, statistical analysis enabled the optimal combination of 3D printing parameters to be established.

报告题目2：MECHANISM FOR HUMAN KNEE JOINT PROSTHESIS

Abstract:The human knee can be considered a simple hinge joint but a more detailed analysis will show that real knee joints have significantly complex kinematics. The complex movement of knee joints is determined by the unique shape of bones, especially the surfaces shape of the femur end and the beginning of the tibia. Analysis has shown that the knee is in fact „rolling“ joint where the tibia rolls on the femur end, and that motion is supported by Ligaments. Ligament arrangement around bones and shapes of contact surfaces defines movement which can be represented by a four-bar mechanism. Modern above-knee prostheses consist of a four-bar mechanism created by suitable metal bars (linkages) connected with hinges which will require some maintenance and lubrication, which can be solved using compliant mechanisms. Compliant mechanisms can offer several advantages over classical mechanisms, such are, no requirements for lubrication and maintenance of hinges also can provide preload necessary for proper prosthesis stability, etc... These are quite good advantages but a synthesis of compliant mechanisms can be quite challenging, especially in a case where new geometry and topology must be designed to achieve the required movement. An interesting case is simply the conversion of a classical mechanism into a compliant one, where hinges will be replaced with deformable (compliant) hinges. With this approach, the simplicity of the classical planar mechanism can be retained with the advantages of compliant mechanisms.

报告题目3：Non-linear dynamics of rolling bearings

Abstract：The rolling bearings is widely used machine elements, very often responsible for machine vibration and noise, as well as for machine failure. The dynamics of rolling bearings occupies the authors during the recent years, striving to describe the dynamics of rolling bearings and solve the task for predictive maintenance and bearing failures avoiding. In this lecture the basics of mathematical modeling of rolling bearing dynamics will be presented. Special attention will be paid to the discussion of the sources of nonlinearity in the mechanics of these complex mechanical systems with multiple contacts. In addition to variable stiffness which occurs in an ideally manufactured and undamaged roller bearing, the focus of the presented research has been on the impact of geometric damage on the raceways’ surfaces. The development of a new mathematical model of non-linear dynamics of rolling bearings will be described in detail. Also, finite element numerical models developed to solve the deformations and stiffness parameters of the bearing’s assembly and elements will be presented and described. The discussion of the performed experimental tests will be directed towards determining the nonlinearity parameters in mathematical models of rolling bearing dynamics.

报告题目4：Efficient Computation Method in Total Fatigue Life Estimation of Aircraft Structural Components

This work considers the numerical computation methods and procedures for the total fatigue predicting of notched structural components. Computation method is based on fatigue life prediction using the strain energy density (SED) method. Based on the strain energy density method, a fatigue crack growth model is developed to predict the lifetime of fatigue crack growth for single or mixed mode cracks. The model is based on an equation expressed in terms of low cycle parameters. Attention is focused on crack growth analysis of structural components under load spectrum. Crack growth is largely influenced by the effect of the plastic zone at the front of the crack. To obtain efficient computation model plasticity-induced crack closure phenomenon is considered during fatigue crack growth. The use of the strain energy density method is efficient for fatigue crack growth prediction under cyclic loading in damaged structural components. Strain energy density method is easy for engineering applications since it does not require any additional determination of fatigue parameters (those would need to be separately determined for fatigue crack propagation phase), and low cyclic fatigue properties are used instead. Accurate determination of fatigue crack closure has been a complex task for years. The influence of this phenomenon can be considered by means of experimental and numerical methods. Both of these models are considered. Finite element analysis (FEA) has been shown to be a powerful and useful tool to analyze crack growth and crack closure effects. Computation results are compared with available experimental results.