scholarly journals RECONSTRUCTION ON THE VOLTAGE OF THE PRE-SLIDING STATE OF THE TRAGICHOUS MOUNTAIN SLOPE LANDSCAPE «AK KAIN»

2021 ◽  
Vol 82 (4) ◽  
pp. 142-150
Author(s):  
A.R. Baymakhan ◽  
◽  
A. Serikkyzy ◽  
G.M. Baymakhanova ◽  
A.K. Rysbaeva ◽  
...  
Keyword(s):  
Finite Element ◽  
Layered Structure ◽  
Strain State ◽  
Tien Shan ◽  
Stress Concentrations ◽  
Mountain Slope ◽  
Inclined Layer ◽  
Element Algorithm ◽  
Northern Tien Shan ◽  
Soil Sediments

The method of reconstruction and investigation of the pre-landslide condition of the tragic landslide «Ak-Kain» of the Northern Tien Shan is proposed. A model and a finite element algorithm for studying the stress-strain state (VAT) of soil sediments of an obliquely layered structure are briefly presented. The established zones and places of accumulation of dangerous stress concentrations along the inclined layer that led to the tragedy are shown. The plots show the found other areas of hazardous stress concentrations prone to destruction.

scholarly journals Mathematical Modeling of the Water Saturation Algorithm of the Mountain Slope on the Example of the Catastrophic Landslide of the Northern Tien Shan Ak Kain

2021 ◽  
Vol 8 (3) ◽  
pp. 467-476
Author(s):  
Rysbek Baimakhan ◽  
Zhanar Kadirova ◽  
Assima Seinassinova ◽  
Aigerim Baimakhan ◽  
Zukhra Abdiakhmetova
Keyword(s):  
Mathematical Modeling ◽  
Finite Element ◽  
Layered Structure ◽  
Water Saturation ◽  
Layer Structure ◽  
Tien Shan ◽  
Original Structure ◽  
Initial Shape ◽  
Soil Deposits ◽  
Northern Tien Shan

The purpose of this article is to present the developed methodology, a brief algorithm of mechanical-and-mathematical modeling to investigate the causes and mechanism of soil disruption from the hillsides and the results of its use for restoring the pre-landslide stress state using the example of one of the tragic landslides. The numerical finite element algorithm of studying the stress–strain state (SSS) of soil deposits of slopes of the inclined-layered structure is briefly described, with specific features of the use of isoparametric elements of the quadrangular shape with four nodes of arbitrary shape. For detailed studying the SSS, the cover soils of the steep slope of the inclined-layered structure, in height from the arch to the foot, are conventionally divided into three zones, each of which has layered structures. Studies of the geometry of its area and the angle of inclination of the slope showed that the two-layer structure of its original structure made a curved path repeating the outline of the gorge. The finite element method helped to model the soil deposits of the slope with the granite-basalt rock as close as possible to the landslide initial shape. The proposed methodology, the mechanical-mathematical model, algorithms and calculation examples allow predicting the possible occurrence of landslides on other countless hillsides of the Northern Tien Shan by determining stress concentration zones.

scholarly journals Influence of a metaphyseal sleeve on the stress-strain state of a bone-tumor implant system in the distal femur: an experimental and finite element analysis

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Jian-jun Li ◽  
Dong-mu Tian ◽  
Li Yang ◽  
Jing-yu Zhang ◽  
Yong-cheng Hu
Keyword(s):  
Finite Element ◽  
Bone Tumor ◽  
Strain State ◽  
Distal Femur ◽  
Stress Concentrations ◽  
Stress Strain ◽  
Von Mises ◽  
Implant System ◽  
Tumor Implant ◽  
Intact Femur

Abstract Background Aseptic loosening of distal femoral tumor implants significantly correlates with the resection length. We designed a new “sleeve” that is specially engaged in the metaphysis at least 5 cm proximal to the knee joint line to preserve as much bone stock as possible. This study investigates the influence of a metaphyseal sleeve on the stress-strain state of a bone tumor implant system in the distal femur. Methods Cortex strains in intact and implanted femurs were predicted with finite element (FE) models. Moreover strains were experimentally measured in a cadaveric femur with and without a sleeve and stem under an axial compressive load of 1000 N. The FE models, which were validated by linear regression, were used to investigate the maximal von Mises stress and the implanted-to-intact (ITI) ratios of strain in the femur with single-legged stance loading under immediate postoperative and osseointegration conditions. Results Good agreement was noted between the experimental measurements and numerical predictions of the femoral strains (coefficient of determination (R2) ≥ 0.95; root-mean-square error (RMSE%) ≈ 10%). The ITI ratios for the metaphysis were between 13 and 28% and between 10 and 21% under the immediate postoperative and osseointegration conditions, respectively, while the ITI ratios for the posterior and lateral cortices around the tip of the stem were 110% and 119% under the immediate-postoperative condition, respectively, and 114% and 101% under the osseointegration condition, respectively. The maximal von Mises stresses for the implanted femur were 113.8 MPa and 43.41 MPa under the immediate postoperative and osseointegration conditions, which were 284% and 47% higher than those in the intact femur (29.6 MPa), respectively. Conclusions This study reveals that a metaphyseal sleeve may cause stress shielding relative to the intact femur, especially in the distal metaphysis. Stress concentrations might mainly occur in the posterior cortex around the tip of the stem. However, stress concentrations may not be accompanied by periprosthetic fracture under the single-legged stance condition.

scholarly journals Mathematical modeling study of the landslide state of the slope of the mountain "SHYM BULAK"

2020 ◽  
Vol 77 (3) ◽  
pp. 259-264
Keyword(s):  
Arbitrary Shape ◽  
Strain State ◽  
Physical And Mechanical Properties ◽  
Element Model ◽  
Tien Shan ◽  
The Road ◽  
Soil Deposits ◽  
Landslide Slope ◽  
Lower Slope ◽  
Northern Tien Shan

The data on the main causes of the causing landslide on the mountain slopes, in particular, the pictures of the landslide-collapse that occurred along the road between the Medeu dam and the Shym Bulak ski sports complex in the gorge of the high slopes of the Trans-Ili Alatau in Northern Tien Shan, are given. It also offers some data on the physical and mechanical properties of loess and loamy soils, with which the cover soils of these slopes are mainly composed. A finite-element model for the study of the stress-strain state (VAT) of soil deposits of slopes of an obliquely layered structure is proposed with instructions on the features of using isoparametric elements of a quadrangular shape with four nodes of an arbitrary shape. The landslide slope of the mountain is modeled by finite elements together with the highway and the lower slope at the foot of which the Kishi Almaty River flows. The results of the VAT study are presented and the places of the slope that are vulnerable to a landslide are identified as dangerous.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

2013 ◽  
Vol 41 (2) ◽  
pp. 127-151
Author(s):  
Rudolf F. Bauer
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Methods ◽  
Mathematical Analysis ◽  
Internal Stresses ◽  
Stress Concentrations ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
And Performance ◽  
Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

scholarly journals High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Atanu Bhattacharya ◽  
Tobias Bolch ◽  
Kriti Mukherjee ◽  
Owen King ◽  
Brian Menounos ◽  
...  
Keyword(s):  
Mass Loss ◽  
River Flow ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Temperature And Precipitation ◽  
Multi Temporal ◽  
The 1960S ◽  
Northern Tien Shan

AbstractKnowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

Mixed finite element algorithm for a nonlinear time fractional wave model

2021 ◽  
Vol 188 ◽  
pp. 60-76
Author(s):  
Jinfeng Wang ◽  
Baoli Yin ◽  
Yang Liu ◽  
Hong Li ◽  
Zhichao Fang
Keyword(s):  
Finite Element ◽  
Mixed Finite Element ◽  
Wave Model ◽  
Element Algorithm

Effective Convergence Checks for Verifying Finite Element Stresses at Three-Dimensional Stress Concentrations

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
J. R. Beisheim ◽  
G. B. Sinclair ◽  
P. J. Roache
Keyword(s):  
Finite Element ◽  
Error Estimation ◽  
A Posteriori Error Estimates ◽  
Three Dimensional ◽  
Posteriori Error ◽  
Test Problems ◽  
A Posteriori ◽  
Stress Concentrations ◽  
Element Analysis ◽  
A Posteriori Error

Current computational capabilities facilitate the application of finite element analysis (FEA) to three-dimensional geometries to determine peak stresses. The three-dimensional stress concentrations so quantified are useful in practice provided the discretization error attending their determination with finite elements has been sufficiently controlled. Here, we provide some convergence checks and companion a posteriori error estimates that can be used to verify such three-dimensional FEA, and thus enable engineers to control discretization errors. These checks are designed to promote conservative error estimation. They are applied to twelve three-dimensional test problems that have exact solutions for their peak stresses. Error levels in the FEA of these peak stresses are classified in accordance with: 1–5%, satisfactory; 1/5–1%, good; and <1/5%, excellent. The present convergence checks result in 111 error assessments for the test problems. For these 111, errors are assessed as being at the same level as true exact errors on 99 occasions, one level worse for the other 12. Hence, stress error estimation that is largely reasonably accurate (89%), and otherwise modestly conservative (11%).

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