scholarly journals Load capacity of the mixed bench and slab foundation. Numerical simulations and analytical calculation model

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Michał Grodecki
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Load Capacity ◽  
Analytical Calculation ◽  
Calculation Model ◽  
Engineering Practice ◽  
Safe Side ◽  
3D Numerical Modelling ◽  
Slab Foundation ◽  
Analytical Approaches

Abstract The paper presents results of a numerical investigation on load capacity of the mixed bench and slab shallow foundations (often used in the process of the modernization of the old, antique buildings, which are suffering from lack of the load capacity). The main trouble with use of existing analytical approaches is a non-unique foundation level of the bench and slab, they could even be founded on different geotechnical layers. Proposed analytical model based on Brinch Hansen (EC-7) approach could deal with such a problem. Results of 2D and 3D numerical modelling (ultimate load of the foundation) are compared to the obtained by using the proposed approach. Influence of the soil above the foundation level is also investigated. Different width to length ratios of the foundation are analyzed (from “short” to “long” foundations). Usability of the proposed analytical model in engineering practice is proved by numerical simulations; the obtained results are on the safe side with quite acceptable margin of additional safety.

scholarly journals A Layer-Dependent Analytical Model for Printability Assessment of Additive Manufacturing Copper/Steel Multi-Material Components by Directed Energy Deposition

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1394
Author(s):  
Wenqi Zhang ◽  
Baopeng Zhang ◽  
Haifeng Xiao ◽  
Huanqing Yang ◽  
Yun Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Additive Manufacturing ◽  
Analytical Model ◽  
Analytical Calculation ◽  
High Strength ◽  
Deposition Process ◽  
Processing Parameters ◽  
Calculation Model ◽  
Optimal Processing ◽  
Directed Energy

Copper/steel bimetal, one of the most popular and typical multi-material components (MMC), processes excellent comprehensive properties with the high strength of steel and the high thermal conductivity of copper alloy. Additive manufacturing (AM) technology is characterized by layer-wise fabrication, and thus is especially suitable for fabricating MMC. However, considering both the great difference in thermophysical properties between copper and steel and the layer-based fabrication character of the AM process, the optimal processing parameters will vary throughout the deposition process. In this paper, we propose an analytical calculation model to predict the layer-dependent processing parameters when fabricating the 07Cr15Ni5 steel on the CuCr substrate at the fixed layer thickness (0.3 mm) and hatching space (0.3 mm). Specifically, the changes in effective thermal conductivity and specific heat capacity with the layer number, as well as the absorption rate and catchment efficiency with the processing parameters are considered. The parameter maps predicted by the model have good agreement with the experimental results. The proposed analytical model provides new guidance to determine the processing windows for novel multi-material components, especially for the multi-materials whose physical properties are significantly different.

The effects of geometric offsets on the dynamic responses of a Scott—Russell amplifying mechanism with flexible hinges

2009 ◽  
Vol 223 (10) ◽  
pp. 2413-2423 ◽  
Author(s):  
C-M Chen ◽  
R-F Fung
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Dynamic Responses ◽  
Analytical Models ◽  
Dynamic Equations ◽  
Magnification Factor ◽  
Flexure Hinges ◽  
Magnification Factors ◽  
Straight Line ◽  
Deviation Factor

The dynamic equations of a micro-positioning Scott—Russell (SR) mechanism associated with two flexible hinges and an offset are developed to calculate output responses. Both rigid and flexible hinges are considered to explore the results. The main features in the kinematics of the SR mechanism are its displacement amplification and straight-line motion, which are widely needed in practical industries. The manufacturing inaccuracy of the SR mechanism definitely causes geometric offsets of flexure hinges, and affects displacement amplification and straight-line output motion. Analytical models based on kinematics and Hamilton's principle are derived to explore the variation of linearity ratio, magnification factor, and deviation factor due to various offsets and link lengths. From numerical simulations for the SR mechanism with various offsets of flexible hinges in the conditions of different link lengths, it is found that offsets of flexure hinges obviously affect the amplifying factor and linearity ratio, and appear to dominate the changes of magnification factors. Moreover, an analytical model is also used to predict magnification factors due to various offsets. Finally, some conclusions concerning the effects of offset on the performance of the SR mechanism are drawn.

scholarly journals Discussion on the Theoretical Basis for Cross-Over Method Applied to Downhole Wave Velocity Test

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qing Dong ◽  
Zheng-hua Zhou ◽  
Su Jie ◽  
Bing Hao ◽  
Yuan-dong Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Wave Velocity ◽  
Theoretical Basis ◽  
Influence Factors ◽  
P Wave ◽  
Engineering Practice ◽  
S Wave ◽  
Simulation Results ◽  
The Cross

At engineering practice, the theoretical basis for the cross-over method, used to obtain shear wave arrival time in the downhole method of the wave velocity test by surface forward and backward strike, is that the polarity of P-wave keeps the same, while the polarity of S-wave transforms when the direction of strike inverted. However, the characteristics of signals recorded in tests are often found to conflict with this theoretical basis for the cross-over method, namely, the polarity of the P-wave also transforms under the action of surface forward and backward strike. Therefore, 3D finite element numerical simulations were conducted to study the validity of the theoretical basis for the cross-over method. The results show that both shear and compression waves are observed to be in 180° phase difference between horizontal signal traces, consistent with the direction of excitation generated by reversed impulse. Furthermore, numerical simulation results prove to be reliable by the analytic solution; it shows that the theoretical basis for the cross-over method applied to the downhole wave velocity test is improper. In meanwhile, numerical simulations reveal the factors (inclining excitation, geophone deflection, inclination, and background noise) that may cause the polarity of the P-wave not to reverse under surface forward and backward strike. Then, as to reduce the influence factors, we propose a method for the downhole wave velocity test under surface strike, the time difference of arrival is based between source peak and response peak, and numerical simulation results show that the S-wave velocity by this method is close to the theoretical S-wave velocity of soil.

Quantitative Analysis of Inner Force Distribution and Load Capacity of Grasps and Fixtures

2002 ◽  
Vol 124 (2) ◽  
pp. 444-455 ◽  
Author(s):  
Youlun Xiong ◽  
Han Ding ◽  
Michael Yu Wang
Keyword(s):  
Quantitative Analysis ◽  
System Design ◽  
Load Capacity ◽  
Point Contact ◽  
Analytical Description ◽  
Engineering Practice ◽  
Force Distribution ◽  
Grasp Planning ◽  
Analysis And Design ◽  
Fixture System

This paper focuses on a quantitative analysis for grasp planning and fixture design based on an analytical description of point contact restraint. In the framework, the analysis deals with the fundamental concepts of restraint cone, freedom cone, force-determinacy and relative form closure. A method is presented to quantify the performance of a fixture (or grasp) with two major characteristics of inner force distribution and load capacity. Two different fixturing (or grasp) models of simplex grasp and elastic grasp are presented. It is shown that the performance of these two types of grasp (or fixturing) could be measured with different performance indices. A minimax index (MMI) and a volume measure are defined for evaluating a simplex grasp, while a measure using the tolerable range of differential motion in the twist space or the allowable load polyhedron in the wrench space would be suitable for quantifying robustness and load capability of an elastic fixture system. Furthermore, for fixture system design a geometric analysis and reasoning procedure is described for the design of locators, clamps and supplementary supports. The aim of these proposed analysis and design techniques is to provide a scientific foundation for automated grasping/fixturing system design in the engineering practice.

PC-Based Computer Modeling of Combustion Processes

1999 ◽  
Author(s):  
Greg W. Gmurczyk ◽  
Ashwani K. Gupta
Keyword(s):  
Numerical Simulations ◽  
Computer Modeling ◽  
Numerical Experiments ◽  
Laboratory Experiments ◽  
Combustion Process ◽  
Numerical Algorithms ◽  
Computer Hardware ◽  
Simplifying Assumptions ◽  
High Level ◽  
Analytical Approaches

Abstract Constant and significant progress in both computer hardware and numerical algorithms, in recent years, have made it possible to investigate complex phenomena in engineering systems using computer modeling and simulations. Advanced numerical simulations can be treated as an extension of traditional analytical-theoretical analyses. In such cases, some of the simplifying assumptions can usually be dropped and the nonlinear interactions between various processes can be captured. One of the most complex engineering processes encountered in industry is a combustion process utilized either for power/thrust generation or incineration. However, even nowadays, because of the high level of complexity of the general problem of a combustion process in practical systems, it is not currently possible to simulate directly all the length and time scales of interest. Simplifying assumptions still need to be made, but they can be less drastic than in analytical approaches. Therefore, another view of numerical simulations is as a tool to simulate idealized systems and conduct numerical experiments. Such numerical experiments can be complementary to laboratory experiments and can also provide more detailed, nonintrusive diagnostics. Therefore, simulations, along with theory and laboratory experiments, can provide a more complete picture and better understanding of a combustion process. As an example of computer modeling of industrial combustion systems, an enclosed spray flame was considered. Such a flame can frequently be encountered in power generation units, turbine engines, and incinerators. Both the physical and mathematical models were formulated based on data from earlier laboratory studies and results obtained for open air spray flames. The purpose of this study was to use those data as model input to predict the characteristics of a confined flame and provide a means of optimizing the system design with a PC computer.

Lastverteilung in Planetenrollengewindetrieben/Description of the load distribution in planetary roller screws

2020 ◽  
Vol 110 (05) ◽  
pp. 322-327
Author(s):  
Christian Brecher ◽  
Thomas Frenken ◽  
Gabriel Axelrad ◽  
Stephan Neus
Keyword(s):  
Load Distribution ◽  
Load Capacity ◽  
Calculation Model ◽  
Axial Stiffness ◽  
Contact Points ◽  
Calculation Results ◽  
Roller Screw ◽  
The Individual ◽  
Individual Contact ◽  
High Load Capacity

Planetenrollengewindetriebe finden aufgrund ihrer hohen Tragfähigkeit Anwendung in Bereichen, in denen Kugelgewindetriebe an ihre Lastgrenzen stoßen. Um ein Berechnungsmodell für Planentenrollengewindetriebe zu entwickeln, wurden Berechnungsmethoden zur Beschreibung der Lastverteilung innerhalb des Planetenrollengewindetriebs entwickelt. Mit diesen lassen sich die in den einzelnen Kontaktpunkten wirkenden Kräfte sowie die Verlagerungen des Gewindetriebs bestimmen. Die Berechnungsergebnisse werden unter anderem für die Berechnung der statischen axialen Steifigkeit und der Ermüdungslebensdauer benötigt.   Due to their high load capacity, planetary roller screws are used in areas where ball screws reach their load limits. To develop a calculation model for planetary roller screws, calculation methods to describe the load distribution within the planetary roller screw were developed in this step. With these methods, the forces acting in the individual contact points as well as the displacements of the screw drive can be determined. The calculation results are required, among other things, for the calculation of static axial stiffness and fatigue life.

scholarly journals Assessment of the Effect of Wind Load on the Load Capacity of a Single-Layer Bar Dome

Buildings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 179
Author(s):  
Dominika Opatowicz ◽  
Urszula Radoń ◽  
Paweł Zabojszcza
Keyword(s):  
Load Capacity ◽  
Single Layer ◽  
Wind Load ◽  
Calculation Model ◽  
Building Housing ◽  
Von Mises ◽  
Actual Configuration ◽  
Geometric Nonlinear Analysis ◽  
Shallow Structure ◽  
Selection Of

The main purpose of the paper was the assessment of the effect of wind load on the load capacity of a single-layer bar dome. Additionally, which numerical method is appropriate for low-rise single-layer bar domes was checked. In order to explain the effect of the height-to-span ratio on the selection of the appropriate calculation model and method of analysis of the bar dome, an example of the known von Mises truss was proposed. Two cases of von Mises truss differing in the height-to-span ratio were considered. For the shallow structure, a significant change in the value of the stiffness matrix determinant and the current stiffness parameter was observed. A similar tendency in the behavior of the structure can be observed on fragments of larger structures, including shallow single-layer steel domes. These problems are described on the basis of the dome, which is located on top of the building housing the restaurant. This structure is subjected to large displacement gradients and the actual configuration is taken into account in analysis. The analysis showed that there is a change in stiffness for these structures, and, therefore, that such structures should be designed according to geometric nonlinear analysis (GNA).

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