scholarly journals Analysis on Boundary Conditions for Elastic Structures

2021 ◽  
Vol 236 ◽  
pp. 05038
Author(s):  
Wx Zhang
Keyword(s):  
Boundary Condition ◽  
Inverse Method ◽  
Rapid Development ◽  
Local Deformation ◽  
Elastic Materials ◽  
Boundary Constraints ◽  
Construction Machinery ◽  
Basic Equations ◽  
Symplectic System ◽  
Elastic Mechanics

With the rapid development of modern industry, elastic materials and structures have been widely used in all walks of life, such as construction, machinery and so on. The traditional elastic mechanics method generally adopts the semi inverse method. However, this method ignores the local deformation caused by boundary constraints and can only find part of the solution of the problem. In this paper, the basic equations of symplectic system are established, and the solutions of various boundary condition problems are given.

scholarly journals Motor shifting and torque distribution control of a multi-motor driving system in electric construction vehicles

2021 ◽  
Vol 13 (6) ◽  
pp. 168781402110284
Author(s):  
Weikang Kong ◽  
Jixin Wang ◽  
Dewen Kong ◽  
Yuanying Cong ◽  
Shuangshi Feng
Keyword(s):  
Power Systems ◽  
Control Method ◽  
Simulation Analysis ◽  
Rapid Development ◽  
Transmission Efficiency ◽  
Torque Distribution ◽  
Driving System ◽  
Construction Machinery ◽  
Improve Energy Efficiency ◽  
Parameter Matching

With the rapid development of the world economic construction and the shortage of energy, it has become a hot research issue to realize the electrification of the vehicle driving system and improve energy efficiency. Most of the electric construction machinery power systems are characterized by low speed and high load. The coordinated driving of multiple motors can increase the output torque and improve the transmission efficiency of the machine on the basis of a compact layout. A novel configuration of electric construction vehicles based on multi-motor and single-speed and its driving torque distribution control method is presented in this paper. The detailed mathematical model is established and the simulation analysis is carried out based on it. The results show that the proposed multi-motor driving system with the control strategy can improve the overall efficiency in the condition of ensuring the driving force when the parameter matching and motors choosing reasonably.

Local Damage Evolution of Double Cantilever Beam Specimens During Crack Initiation Process: A Natural Boundary Condition Based Method

2009 ◽  
Vol 76 (5) ◽  
Author(s):  
Zhenyu Ouyang ◽  
Guoqiang Li
Keyword(s):  
Boundary Condition ◽  
Crack Initiation ◽  
Current Model ◽  
Crack Tip ◽  
Local Deformation ◽  
Interfacial Stress ◽  
Natural Boundary Condition ◽  
Natural Boundary ◽  
Initiation Process ◽  
Cohesive Laws

Cohesive zone models are being increasingly used to simulate fracture and debonding processes in metallic, polymeric, and ceramic materials and their composites. The crack initiation process as well as its actual stress and damage distribution beyond crack tip are important for understanding fracture of materials and debonding of adhesively bonded joints. In the current model, a natural boundary condition based method is proposed, and thus the concept of extended crack length (characteristic length l) is no longer required and more realistic and natural local deformation beyond crack tip can be obtained. The new analytical approach, which can consider both crack initiation and propagation as well as local deformation and interfacial stress distribution, can be explicitly obtained as a function of the remote peel load P with the given bilinear cohesive laws. An intrinsic geometric constraint condition is then used to solve the remote peel load P. The nonlinear response in both the ascending and descending stages of loading is accurately predicted by the current model, as evidenced by a comparison with both experimental results and finite element analysis results. It is found that the local deformation and interfacial stress beyond crack tip are relatively stable during crack propagation. It is also found that, when the cohesive strength is low, it has a significant effect on the critical peel load and loadline deflection. In principle, the approach developed in the current study can be extended to multilinear cohesive laws, although only bilinear cohesive law is presented in this work as an example.

scholarly journals Calculation for Hard Measured Loads on the Travelling Mechanism of Bridge Inspection Vehicle

2018 ◽  
Vol 153 ◽  
pp. 07003
Author(s):  
Meng Han ◽  
Yongneng Lu ◽  
Hongfeng Ma
Keyword(s):  
Driving Force ◽  
Reference Value ◽  
Test Methods ◽  
Principle Of Superposition ◽  
Bridge Inspection ◽  
Construction Machinery ◽  
Side Load ◽  
Fea Simulation ◽  
Elastic Mechanics ◽  
Selection Of

In allusion to the recently problem of some loads to be calculated and hard measured of travel mechanism of bridge inspection vehicle, based on the principle of superposition in the elastic mechanics, the FEA simulation and test methods have been used to research the hard-measured loads on the travel mechanism of bridge inspection vehicle. The calculation case of the driving force in the driving case and the side load in the turning case of traveling mechanism of bridge inspection vehicle have been solved with this method, the results are used to be applied reference for the property optimization and model selection of mechanical bearing inside of travel mechanism of the bridge inspection vehicle. The research method is of well-reference value for the calculation of the unknown loads of whole machine and parts of construction machinery.

Mechanical characterization of porcine liver properties for computational simulation of indentation on cancerous tissue

2020 ◽  
Vol 37 (4) ◽  
pp. 469-490 ◽  
Author(s):  
Yingqiao Yang ◽  
Kewei Li ◽  
Gerhard Sommer ◽  
Kai-Leung Yung ◽  
Gerhard A Holzapfel
Keyword(s):  
Boundary Condition ◽  
Computational Models ◽  
Mechanical Response ◽  
Computational Simulation ◽  
Biological Tissues ◽  
Local Deformation ◽  
Computational Results ◽  
Compression Tests ◽  
Porcine Liver

Abstract An accurate characterization of soft biological tissue properties is essential for a realistic simulation of surgical procedures. Unconfined uniaxial compression tests with specimens affixed to the fixtures are often performed to characterize the stress-stretch curves of soft biological tissues, with which the material parameters can be obtained. However, the constrained boundary condition causes non-uniform deformation during the uniaxial test, posing challenges for accurate measurement of tissue deformation. In this study, we measured the deformation locally at the middle of liver specimens and obtained the corresponding stress-stretch curves. Since the effect of the constrained boundary condition on the local deformation of specimen is minimized, the stress-stretch curves are thus more realistic. Subsequently, we fitted the experimental stress-stretch curves with several constitutive models and found that the first-order Ogden hyperelastic material model was most suitable for characterizing the mechanical properties of porcine liver tissues. To further verify the characterized material properties, we carried out indentation tests on porcine liver specimens and compared the experimental data with computational results by using finite element simulations. A good agreement was achieved. Finally, we constructed computational models of liver tissue with a tumor and investigated the effect of the tumor on the mechanical response of the tissue under indentation. The computational results revealed that the liver specimen with tumor shows a stiffer response if the distance between the tumor and the indenter is small.

A Modified Theory of Magnetic Effects in Elastic Materials

2006 ◽  
Vol 11 (1) ◽  
pp. 23-47 ◽  
Author(s):  
J. L. Ericksen
Keyword(s):  
Calculus Of Variations ◽  
Energy Minimization ◽  
Continuum Theory ◽  
Jump Conditions ◽  
Elastic Materials ◽  
Elastic Deformations ◽  
Magnetic Effects ◽  
Basic Equations ◽  
Modified Theory

Essentially, this is a critique of static theories covering magnetic effects and elastic deformations. For this, I just use general ideas of continuum theory and common ideas from the calculus of variations as it relates to energy minimization. I obtain the basic equations and jump conditions before even mentioning forces and torques, since descriptions of these have been controversial.

Pipe Systems With Micro-Turbines: Water Hammer Considerations

2003 ◽  
Author(s):  
Qinfen Zhang ◽  
Bryan Karney
Keyword(s):  
Boundary Condition ◽  
Numerical Model ◽  
Comprehensive Analysis ◽  
Pipe System ◽  
Flow Balance ◽  
Pipe Networks ◽  
Nodal Flow ◽  
Speed Change ◽  
Pipe Systems ◽  
Basic Equations

Micro and small turbines, as a means of producing clean and renewable energy by transforming hydropower to electricity, can be used extensively in pipe systems. With respect to hydraulic transient modeling, governed turbines have two additional features compared to the more familiar pump boundary condition: namely, wicket gate adjustments and more complicated device characteristics. Based on head balance (or nodal flow balance) considerations, torque (or speed change) relations, and the governor equation, a numerical model of the turbine boundary condition in a pipe system is established. The combinations of the three basic equations under specific situations are then discussed. To verify in a general way this numerical model, a penstock failure at Lapino Power Plant (Poland) is simulated. The current work sets the stage for a more comprehensive analysis of turbines and related unsteady flow issues in topologically complex pipe networks.

Fully Three-Dimensional Viscous Semi-Inverse Method for Subsonic Mixed-Flow and Radial Impeller Design

2009 ◽  
Author(s):  
Min Ji ◽  
T. Q. Dang ◽  
Michael J. Cave
Keyword(s):  
Boundary Condition ◽  
Inverse Method ◽  
Design Method ◽  
Three Dimensional ◽  
Design Procedure ◽  
Navier Stokes ◽  
Mixed Flow ◽  
Surface Design ◽  
Geometrical Constraints ◽  
Inverse Design Method

A new semi-inverse design method for turbomachinery blading is proposed in this paper. Built on a time-marching Reynolds-Averaged Navier-Stokes solver, the proposed design method takes pressure loading, blade tangential thickness, blade stacking line, and flow path contour as prescribed quantities and computes the corresponding three-dimensional blade camber surface. In order to have the option of imposing geometrical constraints on the designed blade shapes, a new algorithm is developed to solve the camber surface at specified spanwise grid-lines, after which the blade geometry is constructed through ruling (e.g. straight-line element) at the remaining spanwise stations. The new semi-inverse algorithm involves re-formulating the boundary condition on the blade surfaces as a hybrid inverse/analysis boundary condition while preserving the fully three-dimensional nature of the flow field. The new design method can be interpreted as a fully three-dimensional viscous semi-inverse method. The ruled camber surface design procedure ensures blade surface smoothness and some control of mechanical integrity, and results in cost reduction for the manufacturing process. The proposed fully three-dimensional semi-inverse method is demonstrated through design modifications of generic industrial mixed-flow and radial impellers which are typically used for gas process applications.

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