ANALYSIS OF SPACE FRAMES WITH GENERALIZED SEMI-RIGID CONNECTIONS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Shujin Duan ◽  
Zhiyue Li ◽  
Meixiang Liu ◽  
Xiaofeng Xie
Keyword(s):  
Mechanical Model ◽  
Stiffness Matrix ◽  
Element Analysis ◽  
Rigid Frame ◽  
Space Frames ◽  
The Matrix ◽  
Reaction Forces ◽  
Element Number ◽  
Rigid Joints ◽  
Independent Zero

A mechanical model and analytic method are proposed, in which, the axial, the shearing and the bending semi-rigid characteristics of space frames are taken into account. An independent zero-length connection element comprising six translational and rotational springs is used to simulate the beam-to-column connection. The model, namely six-spring mechanical model, has an advantage that the element number of structure does not increase. The matrix displacement method is used to analyze mechanism of the model, including element analysis and structural analysis. The stiffness matrix of the element is derived. Some reaction forces at the end of the element are obtained when it is subjected to two kinds of different loads respectively. The obtained stiffness matrix gets the characteristics of symmetry and singularity and that makes the size of total stiffness matrix for semi-rigid frame the same as that for frame with rigid joints.

An Algorithm to Study the Elastodynamics of Parallel Kinematic Machines With Lower Kinematic Pairs

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Alessandro Cammarata ◽  
Davide Condorelli ◽  
Rosario Sinatra
Keyword(s):  
Stiffness Matrix ◽  
Rigid Bodies ◽  
Parallel Kinematic Machine ◽  
Element Analysis ◽  
Stiffness Matrices ◽  
The Matrix ◽  
Parallel Kinematic ◽  
Global Stiffness Matrix ◽  
Local Stiffness

In this paper, an algorithm to help designers to integrate the elastodynamics analysis along with the inverse positioning and orienting problems of a parallel kinematic machine (PKM) into a single package is conceived. The proposed algorithm applies concepts from the matrix structural analysis (MSA) and finite element analysis (FEA) to determine the generalized stiffness matrix and the linearized elastodynamics equations of a PKM with only lower kinematic pairs. A PKM is modeled as a system of flexible links and rigid bodies connected by means of joints. Three cases are analyzed to consider the combinations between flexible and rigid bodies in order to find the local stiffness matrices. The latter are combined to obtain the limb matrices and, then, the global stiffness matrix of the whole robotic system. The same nodes coming from the links discretization are considered to include joint masses/inertias into the model. Finally, a case study is proposed to show some feasible applications and to compare results to commercial software for validation.

scholarly journals Assessing the Flexural Properties of Epoxy Composites with Extremely Low Addition of Cellulose Nanofiber Content

2020 ◽  
Vol 10 (3) ◽  
pp. 1159 ◽  
Author(s):  
Yingmei Xie ◽  
Hiroki Kurita ◽  
Ryugo Ishigami ◽  
Fumio Narita
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Flexural Modulus ◽  
Strengthening Mechanism ◽  
Short Fiber ◽  
Cellulose Nanofiber ◽  
Resin Matrix ◽  
Element Analysis ◽  
Epoxy Resin Matrix ◽  
The Matrix

Epoxy resins are a widely used common polymer due to their excellent mechanical properties. On the other hand, cellulose nanofiber (CNF) is one of the new generation of fibers, and recent test results show that CNF reinforced polymers have high mechanical properties. It has also been reported that an extremely low CNF addition increases the mechanical properties of the matrix resin. In this study, we prepared extremely-low CNF (~1 wt.%) reinforced epoxy resin matrix (epoxy-CNF) composites, and tried to understand the strengthening mechanism of the epoxy-CNF composite through the three-point flexural test, finite element analysis (FEA), and discussion based on organic chemistry. The flexural modulus and strength were significantly increased by the extremely low CNF addition (less than 0.2 wt.%), although the theories for short-fiber-reinforced composites cannot explain the strengthening mechanism of the epoxy-CNF composite. Hence, we propose the possibility that CNF behaves as an auxiliary agent to enhance the structure of the epoxy molecule, and not as a reinforcing fiber in the epoxy resin matrix.

ANSYS Simply Supported Deep Beams Based on the Study of Mechanical Properties

2013 ◽  
Vol 351-352 ◽  
pp. 782-785
Author(s):  
Yong Bing Liu ◽  
Xiao Zhong Zhang
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Mechanical Model ◽  
Work Performance ◽  
Deep Beam ◽  
Analysis Software ◽  
Deep Beams ◽  
Element Analysis ◽  
Simply Supported ◽  
Force Characteristics

Established the mechanical model of simply supported deep beam, calculation and analysis of simple supported deep beams by using finite element analysis software ANSYS, simulated the force characteristics and work performance of the deep beam. Provides the reference for the design and construction of deep beams.

Compressive Deformation of Hollow Microsphere Reinforced Metal Matrix Composites

1994 ◽  
Vol 372 ◽  
Author(s):  
M. T. Kiser ◽  
M. He ◽  
B. Wuj ◽  
F. W. Zok
Keyword(s):  
Aluminum Matrix ◽  
Hollow Microsphere ◽  
Compressive Deformation ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Element Analysis ◽  
Strength Enhancement ◽  
The Matrix ◽  
Matrix Flow ◽  
Measured Strength

AbstractThe compressive deformation characteristics of hollow alumina microsphere reinforced aluminum matrix composites have been studied through both experiments and finite element analysis of unit cell models. Tests have been performed on composites containing around 50 volume percent of microspheres. The effects of the matrix flow stress and microsphere morphology (characterized by the ratio of wall thickness to radius) have been examined. The measured strength enhancement due to the hollow microspheres was found to be considerably less than that predicted by the FEM calculations; a result of microsphere cracking. Experiments have been conducted to document the progression of such damage following casting and mechanical deformation. The potential of this class of composite for impact energy absorption applications is also explored.

scholarly journals Research on a 3-DOF Motion Device Based on the Flexible Mechanism Driven by the Piezoelectric Actuators

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 578 ◽  
Author(s):  
Bingrui Lv ◽  
Guilian Wang ◽  
Bin Li ◽  
Haibo Zhou ◽  
Yahui Hu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Machining Process ◽  
Element Analysis ◽  
3D Motion ◽  
Compliance Modeling ◽  
The Matrix ◽  
Static Performance ◽  
Flexible Mechanism

This paper describes the innovative design of a three-dimensional (3D) motion device based on a flexible mechanism, which is used primarily to produce accurate and fast micro-displacement. For example, the rapid contact and separation of the tool and the workpiece are realized by the operation of the 3D motion device in the machining process. This paper mainly concerns the device performance. A theoretical model for the static performance of the device was established using the matrix-based compliance modeling (MCM) method, and the static characteristics of the device were numerically simulated by finite element analysis (FEA). The Lagrangian principle and the finite element analysis method for device dynamics are used for prediction to obtain the natural frequency of the device. Under no-load conditions, the dynamic response performance and linear motion performance of the three directions were tested and analyzed with different input signals, and three sets of vibration trajectories were obtained. Finally, the scratching experiment was carried out. The detection of the workpiece reveals a pronounced periodic texture on the surface, which verifies that the vibration device can generate an ideal 3D vibration trajectory.

An Exact Three-Dimensional Beam Element With Nonuniform Cross Section

2010 ◽  
Vol 77 (6) ◽  
Author(s):  
M. Jafari ◽  
M. J. Mahjoob
Keyword(s):  
Cross Section ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Direct Method ◽  
Three Dimensional ◽  
Curved Beams ◽  
Element Analysis ◽  
Shear Loads ◽  
Line Passing ◽  
Exact Stiffness Matrix

In this paper, the exact stiffness matrix of curved beams with nonuniform cross section is derived using direct method. The considered element has two nodes and 12 degrees of freedom, with three forces and three moments applied at each node. The noncoincidence effect of shear center and center of area is also considered in this element. The deformations of the beam are due to bending, torsion, tensile, and shear loads. The line passing through center of area is a general three-dimensional curve and the cross section properties may change arbitrarily along it. The method is extended to deal with distributed loads on the curved beams. The stiffness matrix of some selected types of beams is determined by this method. The results are compared (where possible) with previously published results, simple beam finite element analysis and analytic solution. It is shown that the determined stiffness matrix is exact and that any type of beam can be analyzed by this method.

scholarly journals Analysis of Non-Uniform Shrinkage Effect in Box Girder Sections for Long-Span Continuous Rigid Frame Bridge

2018 ◽  
Vol 13 (2) ◽  
pp. 146-155 ◽  
Author(s):  
Zhuoya Yuan ◽  
Pui-Lam Ng ◽  
Darius Bačinskas ◽  
Jinsheng Du
Keyword(s):  
Finite Element ◽  
General Purpose ◽  
Element Analysis ◽  
Box Girder ◽  
Finite Element Program ◽  
Continuous Rigid Frame Bridge ◽  
Rigid Frame ◽  
Shrinkage Effect ◽  
Rigid Frame Bridge

To consider the effect of non-uniform shrinkage of box girder sections on the long-term deformations of continuous rigid frame bridges, and to improve the prediction accuracy of analysis in the design phase, this paper proposes a new simulation technique for use with general-purpose finite element program. The non-uniform shrinkage effect of the box girder is transformed to an equivalent temperature gradient and then applied as external load onto the beam elements in the finite element analysis. Comparative analysis of the difference in deflections between uniform shrinkage and nonuniform shrinkage of the main girder was made for a vehicular bridge in reality using the proposed technique. The results indicate that the maximum deflection of box girder under the action of non-uniform shrinkage is much greater than that under the action of uniform shrinkage. The maximum downward deflection of the bridge girder caused by uniform shrinkage is 5.6 mm at 20 years after completion of bridge deck construction, whereas the maximum downward deflection caused by non-uniform shrinkage is 21.6 mm, which is 3.8 times larger. This study shows that the non-uniform shrinkage effect of the girder sections has a significant impact on the long-term deflection of continuous rigid frame bridge, and it can be accurately simulated by the proposed transformation technique.

A Finite Element Analysis of the Human Temporomandibular Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu
Keyword(s):  
Finite Element ◽  
Temporomandibular Joint ◽  
Reaction Force ◽  
Element Model ◽  
Contact Stresses ◽  
Element Analysis ◽  
Tensile Stresses ◽  
Reaction Forces ◽  
Von Mises ◽  
Von Mises Stresses

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.

Incorporation of Spinal Flexibility Measurements Into Finite Element Analysis

1990 ◽  
Vol 112 (4) ◽  
pp. 481-483 ◽  
Author(s):  
Mack G. Gardner-Morse ◽  
Jeffrey P. Laible ◽  
Ian A. F. Stokes
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stiffness Matrix ◽  
Beam Element ◽  
Technical Note ◽  
Element Analysis ◽  
Spinal Motion ◽  
Spinal Flexibility

This technical note demonstrates two methods of incorporating the experimental stiffness of spinal motion segments into a finite element analysis of the spine. The first method is to incorporate the experimental data directly as a stiffness matrix. The second method approximates the experimental data as a beam element.

Micromechanical Analysis of Nonlinear Response of Unidirectional Composites: A Fundamental Approach

2001 ◽  
Author(s):  
Virendra R. Jadhav ◽  
Srinivasan Sridharan
Keyword(s):  
Mechanical Model ◽  
Nonlinear Response ◽  
Experimental Studies ◽  
Matrix Cracking ◽  
Type Model ◽  
Unidirectional Composites ◽  
The Matrix ◽  
Experimental Response ◽  
Square Cells ◽  
Experimental Comparisons

Abstract Micromechanical models with different representative volume elements have been developed to study their ability to predict nonlinear response of unidirectional composites. A simple, square cells type micro-mechanical model similar to those widely used by other researchers is compared with a more advanced 3-phase finite element based micro-mechanical model. The models utilize the “bulk” properties of the matrix without attempting to “tune” the model to fit with experimental response of laminae. This is a more fundamental approach and constitutes a departure from current practice. The models account for shear softening, matrix cracking and the presence of residual stresses. A smeared cracking approach was used to characterize the micro-cracking in matrix. Experimental studies were performed on laminae, laminates and cylinders made from carbon epoxy composites. Experimental comparisons show that the more accurate micro-mechanical model with proper partial cracking options provides good bounds on experimental response with consistent accuracy. A square cells type model however is not consistent in its predictions, thus raising questions about its applicability in any general micro-mechanics based analysis.

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