Grooved Cam With a Translating Follower Having an Added Ternary-Roller Intermediate Link

2021 ◽  
Author(s):  
Kuan-Lun Hsu ◽  
Tung-Hsin Pan ◽  
Long-Iong Wu
Keyword(s):  
Contact Stress ◽  
Analytical Approach ◽  
Contact Stresses ◽  
Contact Forces ◽  
Force Transmission ◽  
Cam Mechanism ◽  
Contact Points ◽  
The Common

Abstract The paper presents an analytical approach for designing grooved cam mechanisms with a modified arrangement of the common translating follower. That is, an extraneous intermediate link that has three rollers is added between the cam and the common follower. On the basis of an existing cam mechanism with a common roller follower, an extraneous intermediate link that has three rollers is added between the cam and the common follower. Such a cam mechanism has two set of profile and can creating multiple contact points between the cam and the follower at any instant. The two sets of profiles of such a cam mechanism can serve as the grooved types. Since the follower has three rollers that can simultaneously contact the cam at any instant, it can be positive driven along the guided groove of cam contour. The contact forces and contact stresses of such cam mechanisms are analyzed to illustrate the advantage of spreading force transmission and reducing contact stress of this uncommon follower. The obtained results indicate that the contact stress at the surface of the cam and the follower for such a cam mechanism can be reduced by 34% to 42% in comparison to those of cam mechanism with a common translating roller follower.

Grooved cam mechanism with a translating follower having an added ternary-roller intermediate link

2022 ◽  
pp. 1-37
Author(s):  
Kuan-Lun Hsu ◽  
Tung-Hsin Pan ◽  
Long-Iong Wu
Keyword(s):  
Contact Stress ◽  
High Speed ◽  
Analytical Approach ◽  
Contact Stresses ◽  
Contact Forces ◽  
Force Transmission ◽  
Cam Mechanism ◽  
Contact Points ◽  
The Common ◽  
Heavy Loads

Abstract The paper presents an analytical approach for designing grooved cam mechanisms with a modified arrangement of the common translating follower. That is, an intermediate link having three rollers is added between the cam and the common follower. On the basis of an existing cam mechanism with a common roller follower, an intermediate link that has three rollers is added between the cam and the common follower. Such a cam mechanism has two set of profile and can create multiple contact points between the cam and the follower at any instant. The two sets of profiles of such a cam mechanism can serve as the grooved types. Since the follower has three rollers that can simultaneously contact the cam at any instant, it can be positive driven along the guided groove of cam contour. The contact forces and contact stresses of such cam mechanisms are analyzed to illustrate the advantage of spreading force transmission and reducing contact stress of this uncommon follower. The obtained results indicate that the contact stress at the surface of the cam and the follower for such a cam mechanism can be reduced by 30% to 47% in comparison to those of cam mechanism with a common translating roller follower. In conclusion, the cam mechanism with a translating follower having an added ternary-roller intermediate link can be a preferable choice for the applications that follower is against heavy loads or move at high speed.

Positive-Drive Cam Mechanisms With a Translating Follower Having Dual Concave Faces

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Kuan-Lun Hsu ◽  
Hui-An Hsieh ◽  
Long-Iong Wu
Keyword(s):  
Contact Stress ◽  
Contact Stresses ◽  
Contact Forces ◽  
Cam Mechanism ◽  
Constant Diameter ◽  
Constant Breadth ◽  
Lower Contact

This article proposes a cam mechanism with a translating follower that has dual concave faces, and also demonstrates how to design such a mechanism. This is a positive-drive cam mechanism because the dual concave faces of the follower can simultaneously contact the cam at any instant. The contact forces and the contact stresses of the mechanism are analyzed to illustrate the nature and the capability of reducing contact stress of this novel follower. This cam mechanism is found to have lower contact stress over the constant-breadth and the constant-diameter cam mechanisms.

Calculating conjugate cam profiles by vector equations

2003 ◽  
Vol 217 (10) ◽  
pp. 1117-1123 ◽  
Author(s):  
L-I Wu
Keyword(s):  
Analytical Approach ◽  
Common Point ◽  
Cam Mechanism ◽  
Contact Points

This paper presents an analytical approach for determining the profiles of conjugate disc cams. For a conjugate cam mechanism, its two normal lines through the points of contact and the line of centres must always intersect at a common point, which is an instant centre. On this basis, the contact points between the conjugate cam and the follower can be determined according to the locations of instant centres and follower position. The cam profiles, the paths of the cutter and the pressure angles can then be expressed in the form of parametric vector equations. For various types of conjugate cams, the equations for such expressions are formulated, and examples are provided to illustrate the approach. The procedure is especially simple to program.

Disc cam mechanisms with concave-faced followers

2009 ◽  
Vol 223 (6) ◽  
pp. 1443-1448 ◽  
Author(s):  
L-I Wu ◽  
C-H Liu ◽  
T-W Chen
Keyword(s):  
Contact Stress ◽  
Analytical Approach ◽  
Cam Mechanism ◽  
Cam Profile ◽  
Lower Contact

This article proposes an uncommon follower, a concave-faced follower, for a disc cam mechanism and also presents an analytical approach for determining the cam profile. A disc cam mechanism with a concave-faced follower can have the advantage of lower contact stress over that with a flat-faced follower. Two examples are provided to illustrate the nature and capability of reducing contact stress of this uncommon follower.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

Mechanical Analysis of Disc Cam Mechanisms with Negative Radius Roller Translating Follower

2012 ◽  
Vol 184-185 ◽  
pp. 301-306
Author(s):  
Rong Fu Lin ◽  
Yong Chang
Keyword(s):  
Contact Stress ◽  
Mechanical Analysis ◽  
Cam Mechanism

This paper proposes the conditions of no-undercutting and contact-retaining of the disc cam mechanism with negative radius roller follower. Then, it presents the contact stress expression based on the mechanical analysis. In addition, the effects of different parameters on the force and contact stress are analysed. The results show that the contact stress can be reduced by designing the suitable parameters of the cam.

Periodic Response of a Link Coupling With Clearance

1989 ◽  
Vol 111 (2) ◽  
pp. 253-259 ◽  
Author(s):  
Y. S. Choi ◽  
S. T. Noah
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Solution Procedure ◽  
Contact Forces ◽  
Steady State Response ◽  
Algebraic Equations ◽  
State Response ◽  
Contact Points ◽  
Integration Schemes ◽  
Nonlinear Algebraic Equations

The nonlinear, steady-state response of a displacement-forced link coupling with clearance with finite stiffness is determined. The solution procedure is derived from satisfying the boundary conditions at the contact points and then solving the resulting nonlinear algebraic equations by setting the duration of contact as a parameter. This direct approach to determining periodic solutions for systems with clearances with finite stiffness is substantially more efficient than numerical integration schemes. Results in terms of contact forces and durations of contact are pertinent to fatigue and wear studies. Parametric relations are presented for effects of the variation of damping, stiffness, exciting displacement, and gap length on the dynamic behavior of the link pair.

Biomechanical Comparison of Kinematic and Mechanical Knee Alignment Techniques in a Computer Simulation Medial Pivot Total Knee Arthroplasty Model

2021 ◽  
Author(s):  
Young Dong Song ◽  
Shinichiro Nakamura ◽  
Shinichi Kuriyama ◽  
Kohei Nishitani ◽  
Hiromu Ito ◽  
...  
Keyword(s):  
Femoral Component ◽  
Knee Flexion ◽  
External Rotation ◽  
Knee Kinematics ◽  
Lateral Compartment ◽  
Contact Stresses ◽  
Contact Forces ◽  
Medial Compartment ◽  
Tibial Insert ◽  
Medial Pivot

AbstractSeveral concepts may be used to restore normal knee kinematics after total knee arthroplasty. One is a kinematically aligned (KA) technique, which restores the native joint line and limb alignment, and the other is the use of a medial pivot knee (MPK) design, with a ball and socket joint in the medial compartment. This study aimed to compare motions, contact forces, and contact stress between mechanically aligned (MA) and KA (medial tilt 3° [KA3] and 5° [KA5]) models in MPK. An MPK design was virtually implanted with MA, KA3, and KA5 in a validated musculoskeletal computer model of a healthy knee, and the simulation of motion and contact forces was implemented. Anteroposterior (AP) positions, mediolateral positions, external rotation angles of the femoral component relative to the tibial insert, and tibiofemoral contact forces were evaluated at different knee flexion angles. Contact stresses on the tibial insert were calculated using finite element analysis. The AP position at the medial compartment was consistent for all models. From 0° to 120°, the femoral component in KA models showed larger posterior movement at the lateral compartment (0.3, 6.8, and 17.7 mm in MA, KA3, and KA5 models, respectively) and larger external rotation (4.2°, 12.0°, and 16.8° in the MA, KA3, and KA5 models, respectively) relative to the tibial component. Concerning the mediolateral position of the femoral component, the KA5 model was positioned more medially. The contact forces at the lateral compartment of all models were larger than those at the medial compartment at >60° of knee flexion. The peak contact stresses on the tibiofemoral joint at 90° and 120° of knee flexion were higher in the KA models. However, the peak contact stresses of the KA models at every flexion angle were <20 MPa. The KA technique in MPK can successfully achieve near-normal knee kinematics; however, there may be a concern for higher contact stresses on the tibial insert.

Eight-Axle Railcar Carbody Roll Performance: Center of Gravity and Track Wavelength Effects

2006 ◽  
Author(s):  
William Shust ◽  
Nicholas Wilson ◽  
Stan Gurule
Keyword(s):  
Contact Stresses ◽  
Center Of Gravity ◽  
Heavy Duty ◽  
Body Style ◽  
Trade Offs ◽  
The Common ◽  
Center Body

Heavy-duty railcars carry greater than typical payloads by employing additional wheelsets to lessen wheel/rail contact stresses. Rather than the common 4-axle designs, these cars may have up to 16 axles supporting one deck. Traditionally, these car types have not performed as well as desired. As a response, designers have created depressed center body styles to lower the overall center-of-gravity (CG) height. Such designs lead to more complexity and expense. In this investigation, a heavy-duty 8-axle flatcar has been modeled, both with a flat carbody and a depressed body style. Simulations of harmonic roll perturbations were performed using various CG heights, track perturbation wavelengths and operating speeds. Results include comparisons of design versus performance trade-offs.

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