Statistical Estimation of Resistance to Cyclic Deformation of Structural Steels and Aluminum Alloy

Resistance to cyclic loading is a key property of the material that determines the operational reliability of the structures. When selecting a material for structures operating under low-cycle loading conditions, it is essential to know the cyclic deformation characteristics of the material. Low-cycle strain diagrams are very sensitive to variations in chemical composition, thermal processing technologies, surface hardening, loading conditions, and other factors of the material. The application of probability methods enables the increase in the life characteristics of the structures and the confirmation of the cycle load values at the design phase. Most research papers dealing with statistical descriptions of low-cycle strain properties do not look into the distribution of low-cycle diagram characteristics. The purpose of our paper is to provide a probability assessment of the low-cycle properties of materials extensively used in the automotive and aviation industries, taking into account the statistical assessment of the cyclic elastoplastic strain diagrams or of the parameters of the diagrams. Materials with contrasting cyclic properties were investigated in the paper. The findings of the research allow for a review of durability and life of the structural elements of service facilities subjected to elastoplastic loading by assessing the distribution of low-cycle strain parameters, as well as the allowed distribution limits.

Renovation cycle diagram

Introduction. A relatively new form of transformation of the territory in the current urban development, the renovation of quarters, requires close scientific study and methodological justification. Renovated neighborhoods, as well as projects for the construction of new houses, have individual features and characteristics. The authors hypothesize that, despite the variety of characteristics of renovated neighborhoods and projects for the construction of new houses, traditional in-line construction with the allocation of characteristic stages is possible. Materials and methods. To study the actual duration of the stages of creating objects under the renovation program (which is necessary to identify objects of similar duration), a special database was formed in the Scientific and Project Center “City Development”. As of 15.05.2021, 313 objects involved in the renovation program are included in this special database. A thorough verification of the specified database was performed. As a result, 122 objects with a spread of construction duration values from 11 months to 43.2 months are stored in the verified database. In addition, the materials of the information system for ensuring urban planning activities (ISOGD) of Moscow were used. The initial materials allowed us to identify a number of characteristic stages in the renovation program for each object. Results. To analyze the design duration of construction, the set of objects is divided into 2 parts: commissioning in 2021 and commissioning in subsequent years. For each part, histograms of the distribution of the duration of construction of houses during renovation are constructed and it is proved that the law of normal distribution is observed. A schematic model of renovation processes with multiple process durations is presented. The overall duration of the design (project stage) can take 1 year, construction — 2 years, and the combined stages: preparation of documents, relocation and demolition, will approximately take 1 year. This four-year wave cycle is then repeated the required number of times. The calendar plan of renovation for three wave objects with the allocation of the leading stream is presented. The ratio of flow processes during renovation is most clearly reflected in the constructed cyclogram of a multi-rhythmic object flow modified for renovation conditions. Combined schedules of renovation of in-line construction are constructed. Conclusions. Despite the considerable variety of renovated neighborhoods and projects for the construction of new houses, the authors of the article prove that traditional in-line construction with the allocation of characteristic stages is possible. For large contracting organizations, it is realistic to form a multi-rhythmic object flow with the allocation of the construction stage as the leading flow and calculate the renovation cyclogram.

Research on innovative design of a new rope knotter

Aiming at the complex structure and high manufacturing process requirements of traditional knotter, this article proposes a new rope knotting method. Based on the knotting method, a knotter is designed to use a new mechanism which is made up of two new incomplete gear mechanisms to drive rope clamping mechanism and rope hooking and griping mechanism. First, a kinematic cycle diagram of the knotter is determined, and the structures of each key mechanism are designed. Then, a virtual prototype of the knotter is established by Unigraphics and imported into Automated Dynamic Analysis of Mechanical Systems to analyze the kinematic of each key mechanism. The success rate is 98.4% through 500 physical tests on the physical model of the knotter. The results indicate that the knotting method is reliable. The knotter can meet the requirements of structure, posture, and coordination during knotting process. The new knotter has no separate mechanism for cutting rope and tripping out of the rope buckle. Therefore, the structure is simplified and reduces the design and manufacturing difficulties. Furthermore, the new incomplete gear mechanism solves the problem that in the conventional incomplete gear mechanism, the driven gear can swing at a large angle or even cannot be locked in the case when the locking arc of the passive gear is too short.

Methodologies and Approaches in Discrete Event Simulation

This chapter aims to give a comprehensive explanatory platform of simulation background. As this chapter comprises of four sections, it reviews simulation definitions, forms of models, the need for simulation, simulation approaches and modeling notations. Simulation definition is essential in order to set research boundaries. Moreover, the chapter discusses forms of models: scale model of the real system, or discrete and continuous models. Subsequently, the chapter states documentation of several reasons by different authors pertaining to the question of “why simulate?,” followed by a thorough discussion of modeling approaches in respect to general considerations. Simulation modeling approaches are discussed with special emphasis on the discrete events type only: process-interaction, event scheduling, and activity scanning, yet, a slight comparison is made between the different approaches. Furthermore, the chapter discusses modeling notations activity cycle diagram (ACD) with different versions of the ACD. Furthermore, the chapter discusses petri nets, which handle concurrent discrete events dynamic systems simulation. In addition, Monte Carlo simulation is discussed due to its important applications. Finally, the fourth section of this chapter reviews Web-based simulation, along with all three different types of object-oriented simulation and modeling.