The compaction performance of asphalt pavement depends upon not only the material design but also the construction procedure. This paper intends to quantitatively evaluate the impacts of material properties and paving parameters on the paving compaction quality (i.e., the density and uniformity). A vibration model of screed-paving layer interactions was built to simulate the screed vibration response and the vibration transmission to the paving layer with the vibration frequency and material stiffness. Then, the force transmitting ratio (FTR), contact force, moment transmitting ratio (MTR) and transmitting rotation moment were used to evaluate the compaction of the paving layer. Moreover, a quantized density model was proposed to quantitatively predict the paving compaction performance. In contrast to traditional analyses, the transverse amplitude uniformity of the screed was considered in this work. Finally, the simulation model was validated through a field test. The results show that the paving layer stiffness is positively associated with the initial layer density, which depends on the tamper frequency. For the case study in this paper, the optimum frequency is approximately 163 rad/s, 175 rad/s and 190 rad/s when the tamper frequency is 19 rad/s, 57 rad/s and 95 rad/s, respectively. Larger variation coefficient (CV) and density ratio (DR) indicate that the uniformity of the paving layer density distribution and the pavement roughness are worse. Therefore, it is recommended that the screed vibration frequency and mixture stiffness, which both affect the paving layer density and compaction uniformity, should be considered for future construction procedures.

For a micro-indentation hardness test with non-destructivity, the Nix–Gao model is widely used to describe tested hardness or microhardness variation with an indentation depth induced by indentation size effect, in which tested hardness approaches the macrohardness when the indentation depth is large enough. Based on an analysis of hardness measurements on 10 body-centered cubic steels with diverse microstructure, this paper proposes an analytical relation between microhardness to macrohardness ratio and the indentation depth by explicitly linking characteristic indentation depth (a data-fitting parameter) to grain size and ferrite volume fraction using two different methods. In addition, the normal distribution theory is incorporated to consider the inevitable scatter of identical measurements resulting from material heterogeneity and machining/testing errors. Results show that the proposed model, with 96% reliability, can effectively predict microhardness variation with the indentation depth and its scatter.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

This study aims to address the problems existing in the ideological and political education of postgraduate students, and combines the implementation of the mentor responsibility system to explore the role orientation, work content, and practical effects of mentors in the ideological and political education of postgraduate students. Through questionnaire surveys, interviews, and other research methods, the current situation of ideological and political education of postgraduate students under the mentor responsibility system is analyzed, and corresponding optimization strategies are proposed.

In order to evaluate the structural strength of loader working device in a comprehensive and accurate way and obtain the position of load spectrum measuring points of the working device of loader, the finite element model of the working device of ZL50G loader was established with hexahedral elements mesh. The finite element model was built on the stress analysis of the force model of bucket of the working device. The finite element strength analysis was carried out on the working device structure of the loader, and the stress value of the structure under different working conditions was obtained. The locations of the dangerous points of the working device of the loader were effectively determined. The finite element calculation results showed that: the partial load condition in shovel digging operation was the most dangerous working condition, and the moving arm was the largest load-bearing component. The field test was carried out on the working device of loader. The test results showed that the finite element calculation results were in agreement with the test results. The influence factors of the strength analysis of the working device under the load condition were defined. It also made it clear that the action of the lateral force must be taken into account when testing the load spectrum of the working device. The analysis results provide the reference resources for the load spectrum test and fatigue life analysis and structure optimization of the working device.

This study addresses the issues existing in the current cultivation process of outstanding graduate students and explores the collaborative education mechanism among in-school mentors, enterprise mentors, and counselors in the cultivation of outstanding engineers in the mechanical field based on the perspective of Sanquan education (i.e., holistic, full-course, and all-round education). Through exploring this mechanism, we attempt to construct a more scientific and efficient education model to enhance students’ comprehensive quality and practical skills, thereby meeting society’s demand for high-quality talents in the mechanical field.