Dr. Liyang XieProfessor, Northeastern University, China
Speech Title: On Fatigue Damage Definition and Failure Probability Prediction in Probabilistic Framework
Abstract: Fatigue damage is usually defined as ∑ni / Ni , i.e., the sum of the ratios of stress cycle number to fatigue life under different stress levels. When fatigue life needs to be treated as a random variable, such definition will result in complex cumulative damage calculation. Besides, different definition on fatigue damage implies different critical damage for fatigue failure criterion. This paper defines and discusses different fatigue damage definitions and corresponding issues about failure probability prediction under variable amplitude stress histories. It shows that in the situation of fatigue life following the three-parameter Weibull distribution, the fatigue damage defined based on the location parameter, i.e., the threshold of the random life, is appropriate for cumulative fatigue damage calculation and probabilistic fatigue life prediction.
Keywords: Fatigue damage, critical damage, fatigue life, Weibull distribution, failure probability.
Dr. Wen-jian WangProfessor, School of Mechanical Engineering,
Southwest Jiaotong University, China
Speech Title: To be updated
Abstract: To be updated
Dr. Qiang ZhuProfessor, Department of Mechanical and Energy Engineering,
Southern University of Science and Technology, China
Speech Title: Application of High-throughput Compression Creep Testing Method in Rapid Evaluation of Creep Behavior of Superalloys
Abstract: As one of the principals supporting platforms and key technologies of the "Materials Genome Initiative", high-throughput experimental technology has drastically transformed the landscape of material development by substantially reducing both the development time and associated costs. One area where this impact is particularly evident is in the development of materials for aeroengines and gas turbine blades, where creep testing is a vital component of the development process. Traditionally, tensile creep testing methods have been utilised, but these are both time-consuming and expensive. In response to this challenge, this study introduces a novel approach of a rapid compression creep technique. This innovative method facilitates simultaneous testing of eight samples, thus significantly reducing the time and cost compared to traditional methods. Crucially, this study has successfully utilized the compression creep data to establish a quantitative correlation with tensile creep data, leading to accurate predictions of stress rupture life. Furthermore, this new testing method can also be employed for the rapid screening of creep properties during the development of new materials, allowing for a swift determination of creep stress exponents. This technique also offers the capability to screen the chemical composition of engineering materials. Thus, the rapid compression creep technique represents a significant advance in the field, offering a new method for the rapid evaluation of high-temperature performance in superalloys.
Keywords: High-throughput experimental technology, compressive and tensile creep, evaluation of creep behavior.
Dr. Soon-Gil YoonProfessor, Department of Materials Science and Engineering,
Chungnam National University, Republic of Korea
Speech Title: Mechanical Strength of SZO-PTFE and ZnO-PTFE Films for High-Sensitivity Touch Sensor Applications
Abstract: Flexible and transparent antimicrobial touch/tactile sensors have received considerable attention on account of their wider applicability in personal electronic devices. For electronic devices, coated films should have an enough mechanical strength because of many touches in the case of smart phone applications. Herein, SZO-PTFE and ZnO-PTFE composite thin films with sensorial capabilities and high mechanical strengths are developed via a co-sputtering technique. Mechanical strengths of the composite films were investigated via micro-indenter. Their mechanical strengths showed similar results to that of the glass substrate. Elastic modulus and hardness of the ZnO-PTFE composite films showed almost 90 GPa (that of glass: 70 GPa) and 5.5 GPa (that of glass: 6.1 GPa), respectively. They showed a good adhesion between composite films and glass substrate via adhesive tape test. Furthermore, the linear response of the TENG to driven pressure indicates its excellent pressure-sensing ability, with an unprecedented sensitivity of 75.31 V/kPa and a touch sensitivity of 31.36 V/kPa. Further, the real-time application of ZnO-PTFE as display coating and self-powered touch sensor is demonstrated. This work demonstrates a simple route towards the design of smart coatings with high mechanical strengths.
Dr. Raffaele CucuzzaDepartment of Structural, Geotechnical and Building Engineering, Politecnico di Torino, Italy
Speech Title: An Alternative Approach for Reversing the Structural Design Process: from the Traditional Minimum-weight Approach to the Cutting Losses Minimization
Abstract: Since the beginning of the structural optimization field, the optimal design was characterized by the least-weight configuration. In this sense, all the researchers agreed on adopting the minimum-weight optimization statement as the most promising approach to achieve an optimized employment of material. However, especially for steel structures, this approach completely fails the primary goal of encouraging standardization of pieces during the production phase and reducing constructability issues at the assembly and erection phase. Except for rare cases, increasing diversity among structural elements (i.e. different lengths, different cross-sections and/or materials) leads to a dramatic increase in the financial cost as well as the environmental impact of the structure because of the material waste generated during the cutting procedure.
In this research, a Genetic Algorithm (GA) has been developed and the well-known one-dimensional bin packing problem (BPP) has been implemented within the structural optimization process. The Objective Function formulation lies in a marked change of the paradigm in which the target function is represented by the amount of steel required by the factory instead of the structural cost (e.g. weight). The proposed approach is tested on different steel structures with an increasing number of pieces moving from 2D truss beams to 3D domes. The best design is obtained by varying the size and the overall layout ensuring optimal stock of existing elements.
Finally, comparisons between the traditional minimum-weight approach and the proposed one have been provided for each case study, and economic and environmental benefits deriving from the latter have been discussed.
More Speakers will be updated soon …