axial forces
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Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 562
Author(s):  
Ying Hao ◽  
Ming Gao ◽  
Jiajie Gong

The study of the bifurcation, random vibration, chaotic dynamics, and control of laminated composite beams are research hotspots. In this paper, the parametric random vibration of an axially moving laminated shape memory alloy (SMA) beam was investigated. In light of the Timoshenko beam theory and taking into consideration axial motion effects and axial forces, a random dynamic equation of laminated SMA beams was deduced. The Falk’s polynomial constitutive model of SMA was used to simulate the nonlinear random dynamic behavior of the laminated beam. Additionally, the numerical of the probability density function and power spectral density curves was obtained through the Monte Carlo simulation. The results indicated that the large amplitude vibration character of the beam can be caused by random perturbation on axial velocity.


Astrodynamics ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 39-52
Author(s):  
Qi Li ◽  
Wei Rao ◽  
Xiaoli Cheng ◽  
Haogong Wei ◽  
Chuang Wang ◽  
...  

AbstractThe clear differences between the atmosphere of Mars and the Earth coupled with the lack of a domestic research basis were significant challenges for the aerodynamic prediction and verification of Tianwen-1. In addition, the Mars entry, descent, and landing (EDL) mission led to specific requirements for the accuracy of the aerodynamic deceleration performance, stability, aerothermal heating, and various complex aerodynamic coupling problems of the entry module. This study analyzes the key and difficult aerodynamic and aerothermodynamic problems related to the Mars EDL process. Then, the study process and results of the design and optimization of the entry module configuration are presented along with the calculations and experiments used to obtain the aerodynamic and aerothermodynamic characteristics in the Martian atmosphere. In addition, the simulation and verification of the low-frequency free oscillation characteristics under a large separation flow are described, and some special aerodynamic coupling problems such as the aeroelastic buffeting response of the trim tab are discussed. Finally, the atmospheric parameters and aerodynamic characteristics obtained from the flight data of the Tianwen-1 entry module are compared with the design data. The data obtained from the aerodynamic design, analysis, and verification of the Tianwen-1 entry module all meet the engineering requirements. In particular, the flight data results for the atmospheric parameters, trim angles of attack, and trim axial forces are within the envelopes of the prediction deviation zones.


2022 ◽  
Author(s):  
Helena Barros ◽  
Joaquim Figueiras ◽  
Carla Ferreira ◽  
Mário Pimentel

2022 ◽  
Vol 8 (1) ◽  
pp. 81-91
Author(s):  
Dang Van Kien ◽  
Do Ngoc Anh ◽  
Do Ngoc Thai

Geotechnical problems are complicated to the extent and cannot be expected in other areas since non-uniformities of existing discontinuous, pores in materials and various properties of the components. At present, it is extremely difficult to develop a program for tunnel analysis that considers all complicated factors. However, tunnel analysis has made remarkable growth for the past several years due to the development of numerical analysis method and computer development, given the situation that it was difficult to solve formula of elasticity, viscoelasticity, and plasticity for the dynamic feature of the ground when the constituent laws, yielding conditions of ground materials, geometrical shape and boundary conditions of the structure were simulated in the past. The stability of rock mass around an underground large cavern is the key to the construction of large-scale underground projects. In this paper, the stability analysis was carried out based on those parameters by using 2D FEM RS2 program. The calculated stress and displacements of surrounding rock and rock support by FEM analysis were compared with those allowable values. The pattern of deformation, stress state, and the distribution of plastic areas are analyzed. Finally, the whole stability of surrounding rock mass of underground caverns was evaluated by Rock Science - RS2 software. The calculated axial forces were far below design capacity of rock bolts. The strong rock mass strength and high horizontal to vertical stress ratio enhanced safe working conditions throughout the excavation period. Thus wide span caverns and the system of caverns could be stability excavated sedimentary rock during the underground cavern and the system of caverns excavation by blasting method. The new method provides a reliable way to analyze the stability of the caverns and the system of caverns and also will help to design or optimize the subsequent support. Doi: 10.28991/CEJ-2022-08-01-06 Full Text: PDF


Author(s):  
Sandeep Haritwal

Abstract: In India, every industry has its own importance to make the country shift towards its future goal. The construction industry plays a very significant role with the introduction of high-rise structures that has been increasing regularly. Beside this, the structure should be strong enough that each element should be economic and strong. The criteria of using optimum size approach for reduction of axial forces in column in multi storied building under seismic zone is a new idea. It reduces the size of beams and columns at the different levels of the building. On other hand, the structural weight should be minimized when the self-weight of the same will be reduced and proved to be an economic structure. In this project a G+13 Storey structure is analyzed using six different cases named as AFR Case A to AFR Case F assumed to be situated in seismic Zone III. The plinth area is in use as 625 m2 and all the cases have compared with each parameter. The project concluded that efficient Case is AFR Case C on comparing 6 maximum axial force reduction cases that ultimately reduce the overall cost of the project. Keywords: Axial forces, Columns, Strength, Durability, Software Models, High-Rise Structures


2021 ◽  
pp. 108128652110533
Author(s):  
Yijie Liu ◽  
Aizhong Lu ◽  
Xiangtai Zeng

Analysis of the mechanical behavior of rock mass reinforced by fully grouted rock bolts is introduced based on the interaction between the rock mass and the bolts. The model is based on the following premises: (1) the elastic behavior of the rock mass and rock bolts; (2) the plane strain condition; (3) a deeply buried circular tunnel; (4) complete contact between the bolts and the surrounding rock, that is, they are bonded together; (5) the loads on the surrounding rock from the fully grouted rock bolts are replaced by innumerable concentrated forces along the longitudinal direction of the bolts. For this, the analytical radial displacement solution for a deeply buried circular tunnel subjected to concentrated forces at arbitrary points in surrounding rock is derived. As long as this displacement solution is integrated along the length direction of the bolt, the effect of the bolt on the surrounding rock can be obtained. According to the complete contact condition at the anchoring interface and the force balance condition of the bolts, under the action of the in situ stress, linear equations made up of shear stresses on the bolts are established, from which the distribution of shear stresses and axial forces along the bolts can be solved. Model simulations confirm the previous findings that each installed bolt has a pick-up length, an anchor length and a neutral point. Besides, the influence of the parameters of the rock bolts and the surrounding rock are discussed. The conclusion is consistent with the results of a practical project without adopting any empirical equations. The results of this method can provide a theoretical basis for the design and layout of rock bolts in underground caverns.


2021 ◽  
Vol 9 (3) ◽  
pp. 050-058
Author(s):  
Miloš Matúš ◽  
Peter Križan ◽  
Ľubomír Šooš ◽  
Juraj Beniak

Paper is focused on development of new patented construction of screw briquetting machine for compacting biomass into the solid biofuel. Developed machine design is based on achieved results of comprehensive research of the complicated process of biomass densification. Patented construction provides two main goals: the elimination of axial forces, which causes increasing of bearings lifetime, and a new modular design of pressing chamber and tools with geometry based on application of the mathematical model. Research of the biomass densification pointed to the need for modular design of densification machine, where it is possible to control all significant parameters of the densification process. The goal of this paper is to present a new patented design of screw press, which satisfies all requirements for modularity and control of the parameters. It allows optimizing this process for different types of raw materials and achieving high quality production. Results of experimental research of densification process then allow the engineering design of the production machine tailor-made to the customer, while being able to minimize investment, energy and operating costs. The developed design of screw press is unique in its modularity and high reliability.


2021 ◽  
pp. 34-40
Author(s):  
Maulana Ishaq ◽  
Rita Nasmirayanti ◽  
Asri Yuda Trinanda

Concrete is the main material factor in a construction project field that is often used, because concrete has a high compressive strength value so it is very useful for structural buildings to withstand axial forces or compressive forces on the building itself where the structure can be used. for the long term. However, along with the increase in construction development in Indonesia, it has a negative impact on the environment around the construction site because with the rampant construction of this building it will trigger environmental pollution due to the remaining concrete waste from the construction project. On this basis, it encourages the author to conduct research by utilizing waste concrete as a substitute for coarse aggregate for the compressive strength of concrete, by reusing the concrete waste will increase the life of the material from the waste itself. In this study, the materials used were tested first, such as; cement density, silt content, water content, specific gravity absorption, wear testing and sieve analysis on aggregates. Then for the concrete mixture using concrete waste with variations of 0%, 25%, 50%, 75% and 100% of the total weight of coarse aggregate. In this study, the compressive strength at the age of 21 days with a mixture of 0%, 25%, 50%, 75%, and 100% concrete had a compressive strength of 200.92 kg/cm2, 188.83 kg/cm2, 206, respectively. 96 kg/cm2, 177.50 kg/cm2, and 179.01 kg/cm2. Then experienced an average shrinkage of 9.53 kg/cm2 at the age of 28 days. The optimum compressive strength is at 50% mixed variation, with a value of 206.96 kg/cm2 because it has an increase of 3% higher than normal concrete compressive strength with a mixing ratio of 1:2.5:3.5 and a slump value of ±13.25 cm and the dry weight of the concrete is 7.69 kg.


2021 ◽  
Vol 8 ◽  
Author(s):  
Olivia Mair ◽  
Patrick Pflüger ◽  
Kai Hoffeld ◽  
Karl F. Braun ◽  
Chlodwig Kirchhoff ◽  
...  

Tibial pilon fractures were first described by Étienne Destot in 1911. He used the French word “pilon” (i.e., pestle), to describe the mechanical function of the distal tibia in the ankle joint. This term has further been used to portray the mechanism involved in tibial pilon fractures in which the distal tibia acts as a pestle with heavy axial forces over the talus basically causing the tibia to burst. Many different classification systems exist so far, with the AO Classification being the most commonly used classification in the clinical setting. Especially Type C fractures are extremely difficult to manage as the high energy involved in developing this type of injury frequently damages the soft tissue surrounding the fracture zone severely. Therefore, long -term outcome is often poor and correct initial management crucial. In the early years of this century treatment has evolved to a two–staged protocol, which nowadays is the gold standard of care. Additional methods of treating the soft tissue envelope are currently being investigated and have shown promising results for the future. The aim of this review is therefore to summarize protocols in managing these difficult fractures, review the literature on recent developments and therefore give surgeons a better understanding and ability to handle tibial pilon fractures.


2021 ◽  
Author(s):  
Rafid Saeed Atea

Abstract Four full concrete columns have been created Tested below high temperature for The fire resistance of concrete elements in concrete with particular compressive strengths. The standard concrete with compressive strength values of C25 were made of one of the four specimens, while the rest were made of C35, C60 and C75 respectively, respectively. During simulation of Within the laboratory furnace, the same For the specimens, axial forces were applied. Many experimental outcomes parameters were evaluated in contrast, including temperature changes, Vertical moving, side deflection, fire resistance and Failed properties of the specimen. The results have shown a rise in the compressive strength of the concrete for the concrete columns from the outside up to the inside of the column the same cross section of the lower compressive forces of concrete display better fire resistance efficiency with the same initial axial strength ratio. The C35, C60 and C75 columns' fire resistance is higher than standard concrete columns. The initial and secant rigidity of the columns of Reinforced concrete (RC) has also The percentage decreased dramatically after fire exposure and the temperature increased from 25 to 750 ° C.


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