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.

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.

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.

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.

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.

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.

The Effect of Body Position and Number of Supports on Wall Reaction Forces in Rock Climbing

1997 ◽  
Vol 13 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Franck Quaine ◽  
Luc Martin ◽  
Jean-Pierre Blanchi
Keyword(s):  
Body Weight ◽  
Contact Force ◽  
Body Position ◽  
Three Dimensional ◽  
Rock Climbing ◽  
Contact Forces ◽  
Vertical Posture ◽  
Reaction Forces ◽  
Force Data ◽  
Lower Contact

This manuscript describes three-dimensional force data collected during postural shifts performed by individuals simulating rock-climbing skills. Starting from a quadrupedal vertical posture, 6 expert climbers had to release their right-hand holds and maintain the tripedal posture for a few seconds. The vertical and contact forces (lateral and anteroposterior forces) applied on the holds were analyzed in two positions: an “imposed” position (the trunk far from the supporting wall) and an “optimized” position (the trunk close to the wall and lower contact forces at the holds). The tripedal postures performed in the two positions were achieved by the same pattern of vertical and contact forces exerted by the limbs on the holds. In the optimized position, the transfer of the forces was less extensive than in the imposed position, so that the forces were exerted primarily on the ipsilateral hold. Moreover, a link between the contact force values and the couple due to body weight with respect to the feet was shown.

Evaluating Measured Tire Contact Stresses to Predict Pavement Response and Performance

2000 ◽  
Vol 1716 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Reynaldo Roque ◽  
Leslie Ann Myers ◽  
Bjorn Birgisson
Keyword(s):  
Contact Stress ◽  
Contact Stresses ◽  
Embedded Sensors ◽  
Stress Distributions ◽  
Near Surface ◽  
Weak Bases ◽  
Truck Tires ◽  
Pavement Response ◽  
Pavement Structures ◽  
And Performance

Recent research has indicated that measured contact stress distributions under radial truck tires are highly complex. These stress distributions help to explain near-surface distresses that have become more prevalent since the inception of radial tires, indicating that realistic contact stresses must be considered when pavement response and performance are evaluated. However, because of the complexities involved in measuring contact stresses under tires, obtaining these measurements directly on real pavements is not possible. Consequently, contact stress measurements have been made on systems having rigid foundations with embedded sensors. Therefore, determining whether tire contact stresses measured on a rigid foundation are significantly different from contact stresses under the same tire on an actual pavement is critical. Finite element analyses conducted indicated that both vertical and lateral tire contact stresses measured on rigid foundations accurately represent the contact stresses for the same tire on typical asphalt pavement structures. Some minor differences were observed for thin (50-mm surface) pavements on weak bases, but the correspondence in terms of both distribution and magnitude was still very good. The conclusion was that contact stresses measured by devices with rigid foundations appear to be suitable for predicting response and performance of highway pavements.

Contact Stress Reduction Mechanisms for the CAM-Based Infinitely Variable Transmission

2007 ◽  
Author(s):  
Derek F. Lahr ◽  
Dennis W. Hong
Keyword(s):  
Contact Stress ◽  
Stress Reduction ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Speed Ratio ◽  
Cam Mechanism ◽  
Expected Performance ◽  
Differential Mechanism ◽  
Variable Transmission ◽  
Infinitely Variable Transmission

The Cam-based Infinitely Variable Transmission (IVT) is a new type of ratcheting IVT based on a three dimensional cam and follower system which provides unique characteristics such as generating specific functional speed ratio outputs including dwells, for a constant velocity input. This paper presents several mechanisms and design approaches used to improve the torque and speed capacity of this unique transmission. A compact, lightweight, and capable differential mechanism based on a cord and pulley system is developed to double the number of followers in contact with the cam at any time, thereby reducing the contact stress between the followers and the cam surface considerably. A kinematic model governing the motion of this differential is developed and a few experimental results from the prototype are presented, showing an overall increase in performance including a smooth output, a wide gear range, and the ability to shift under load. Plans for future improvements to the design, including an inverted external cam mechanism, is also presented along with the expected performance gains.

scholarly journals Contact stresses in point frogs

2020 ◽  
Vol 164 ◽  
pp. 03034
Author(s):  
Boris Glusberg ◽  
Vadim Korolev ◽  
Olga Lokteva ◽  
Irina Shishkina
Keyword(s):  
Stress State ◽  
Contact Stress ◽  
Contact Stresses

The methodology for calculating the contact stress state for various contact types of frogs and wheel is presented. The magnitudes of contact stresses in the frogs can be calculated according to the Hertz-Belyaev method, taking into account certain evaluating factors.

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