Assessment of the Dynamic Quality of a Class of Dwell-Rise-Dwell Cams

1981 ◽  
Vol 103 (4) ◽  
pp. 793-802 ◽  
Author(s):  
F. Y. Chen
Keyword(s):  
High Speed ◽  
Amplification Factor ◽  
Response Characteristics ◽  
Vibrational Response ◽  
The Past ◽  
Acceleration Amplification ◽  
Cam Follower ◽  
Cam Profile ◽  
Dynamic Quality

A number of new cam profiles of the dwell-rise-dwell type have been proposed by different researchers in the past two decades. They were claimed as efficient cam curves suitable for high-speed applications. This paper re-examines these profiles with regard to the important vibrational response characteristics when they are applied as motion excitations to a cam-and-follower system. The severity of the dynamic response of the cam follower to the motion excitation of a cam will be measured by a dimensionless quantity known as the normalized acceleration amplification factor (NAAF). A simplified response envelop for the residual vibration of NAAF versus the fundamental period is constructed so that an assessment of the merit of any given cam profile can be made qualitatively and quantitatively.

A Versatile Cam Profile for Controlling Interface Force in Multiple-Dwell Cam-Follower Systems

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
Closed Form ◽  
High Speed ◽  
Maximum Magnitude ◽  
Design Objective ◽  
Standard Equation ◽  
Negative Acceleration ◽  
Cam Follower ◽  
Cam Profile ◽  
Harmonic Analyses ◽  
Spreadsheet Software

Cam follower systems are widely used in manufacturing because of their precise motion and ability to easily dwell. The cam typically drives a follower in some precise motion needed to accomplish a manufacturing task. Presented in this paper is a closed-form modified trapezoidal cam motion function with adjustable positive and negative acceleration. The profile is suitable for multiple-dwell cam and follower applications. The profile is particularly applicable to high-speed cams in which the follower acceleration is a primary design objective. The main benefit of the profile is that it allows cam designers to easily set limits on the positive and negative acceleration to achieve design objectives. Additional benefits are that the cycle jerk is continuous and that the cam designer can control the maximum magnitude of jerk. The motion program is presented in closed-form for easy implementation in standard equation-solver or spreadsheet software. Dynamic and harmonic analyses are presented to illustrate the benefits of the profile.

Synthesis and Steady State Analysis of High-Speed Elastic Cam-Follower Linkages With Concentrated Masses: Part I — Theory

1991 ◽  
Author(s):  
Hsin-Ting J. Liu ◽  
Donald R. Flugrad
Keyword(s):  
Steady State ◽  
Iterative Procedure ◽  
High Speed ◽  
Linear Ordinary Differential Equations ◽  
Periodic Linear ◽  
Cam Follower ◽  
Cam Profile ◽  
Concentrated Masses ◽  
Design Speed ◽  
Steady State Solutions

Abstract A cam driving a lumped inertia through a massless, elastic, slider-crank follower linkage with two concent rated masses located at the pin joints is considered. An iterative procedure taking the elasticity, damping, and changing geometry of the linkage into account is developed for synthesizing the cam profile to produce a desired output motion at a given design speed. The steady state solutions for the inhomogeneous, periodic, linear, ordinary differential equations are solved numerically by Hsu’s method.

Synthesis and Steady State Analysis of High-Speed Elastic Cam Follower Linkages by a Finite Element Method

1991 ◽  
Author(s):  
Hsin-Ting J. Liu ◽  
Donald R. Flugrad
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Speed ◽  
The Finite Element Method ◽  
Linear Ordinary Differential Equations ◽  
Periodic Linear ◽  
Cam Follower ◽  
Cam Profile ◽  
Design Speed ◽  
Element Method

Abstract A cam driving a lumped inertia through an elastic slider-crank follower linkage with a curved beam coupler is considered. An iterative procedure utilizing the finite element method developed by Midha et al. (1978) is used to synthesize the cam profile to produce a desired output motion at a given design speed and damping coefficient. Nonlinear terms are neglected producing inhomogeneous. periodic, linear, ordinary differential equations. Response of the synthesized linkages are simulated and found to be satisfactory at the design conditions.

Synthesis and Analysis of Cam-Follower Systems With Two Degrees of Freedom

1989 ◽  
Author(s):  
D. M. Tsay ◽  
C. O. Huey
Keyword(s):  
Finite Element ◽  
Collocation Method ◽  
Degrees Of Freedom ◽  
Approximate Solutions ◽  
Spline Collocation ◽  
Spline Collocation Method ◽  
Vibrational Response ◽  
Cam Follower ◽  
Cam Profile

Abstract A general, integrated, and systematic procedure for the synthesis and analysis of non-rigid cam-follower systems is presented. The method is based on a linear, lumped, two-degree-of-freedom (two-DOF) model and uses spline functions for the synthesis of output motions. Solution techniques for differential equations are identified that make the method sufficiently fast and efficient to be employed in an iterative design process. For the equations that occur in the determination of the cam profile the finite element spline collocation method is used to obtain approximate solutions. To analyze the vibrational response of the follower system, both the finite element spline collocation method and the Crank-Nicolson method are applied. The overall procedure offers the advantage over other procedures of greater generality yet requires only routine application procedures. An example is provided to illustrate the complete synthesis/analysis procedure and the results are compared to those obtained using a traditional polynomial approach.

Mathematical modeling and simulation of high-speed cam mechanisms to minimize residual vibrations

2014 ◽  
Vol 228 (13) ◽  
pp. 2402-2415 ◽  
Author(s):  
Halit Kaplan
Keyword(s):  
Mathematical Modeling ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Dimensionless Analysis ◽  
Multipliers Method ◽  
Cam Follower ◽  
Cam Profile

Mathematical modeling, simulation, and optimum design of equivalent one degree-of-freedom high-speed cam mechanisms used for internal combustion engines are investigated in this study. The dynamic equation governing the dynamic behavior of a typical high-speed cam–follower system of an internal combustion engine has been simplified using dimensionless analysis method. The resulting model is then used to find the optimum cam shape to reduce the residual vibrations in the follower part of the system. The Lagrange multipliers method is utilized to minimize the sum of squared error (deviation from the cam profile) over one period under continuity and smoothness constraints.

scholarly journals Research on Seismic Dynamic Response Characteristics of Weak Surrounding Rock Slope With Double-Arch Tunnel

2021 ◽  
Author(s):  
Xueliang Jiang ◽  
Yonghui Qian ◽  
Jiqi Zhang ◽  
Yong Liu ◽  
RiWe Deng ◽  
...  
Keyword(s):  
Seismic Wave ◽  
Amplification Factor ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Dynamic Displacement ◽  
Displacement Response ◽  
Response Characteristics ◽  
Acceleration Amplification ◽  
Dynamic Response Characteristics ◽  
Peak Value

Abstract Through the shaking table test, Wenchuan wave (WC) was used as the excitation wave of the shaking table test. The vibration was excited in three directions: horizontal (x), vertical (z), and horizontal and vertical (xz) and the dynamic response characteristics of rock slopes was studied. The results show:(1) The acceleration amplification factor of each measuring point of the slope shows a nonlinear increasing trend with the increase of the slope height.The slope changes the frequency spectrum of the loaded seismic wave.The slope has a filtering effect on the high frequency band of the seismic wave.(2) Under the unidirectional cyclic loading of Wenchuan wave, the slope acceleration amplification factor increases with the increase of the peak value of the seismic wave. Under the bi-directional excitation of Wenchuan wave, the slope acceleration amplification coefficient generally decreases with the increase of the peak value of the seismic wave.The slope acceleration amplification factor presents the characteristics of first increasing and then decreasing with the increase of the relative height of the slope.(3) The dynamic displacement response characteristics of the tunnel slope with double-arch tunnel are mainly affected by the seismic wave in the same direction and the peak value of the dynamic displacement response increases with the increase of the seismic wave peak value.(4) The peak dynamic displacement response of the double-arch tunnel slope shows a non-linear change trend with the increase of slope height. The dynamic displacement peak growth rate is slower below the rock interface and the dynamic displacement peak increases rapidly above the interface and Maximum displacement occurred at the top of the slope.

Theoretical and Statistical Analysis of Ship Grounding Accidents

2000 ◽  
Vol 122 (3) ◽  
pp. 200-207 ◽  
Author(s):  
Bo Cerup Simonsen ◽  
Peter Friis Hansen
Keyword(s):  
Statistical Analysis ◽  
Kinetic Energy ◽  
Energy Absorption ◽  
High Speed ◽  
Rational Design ◽  
Impact Damage ◽  
The Past ◽  
Damage Stability ◽  
Ship Grounding

Today, the ship kinetic energy and structural crushing resistance is not taken into account in any regulation concerned with the damaged state of a conventional ship (damage stability, oil outflow, etc.). However, the past few years of experience with high-speed craft (HSC) have clearly demonstrated that impact damage is indeed related to the kinetic energy and the strength of the ship. The present paper discusses various aspects related to rational design against grounding accidents. A relatively simple theory is reviewed for comparing the expected grounding damage of different ships, taking into account the structure, the displacement and the sailing velocity. It is shown that based on simple requirements of similitude, it is possible to scale certain types of grounding bottom damage. Then 130 grounding accidents are investigated. Attempts are first made at identifying the governing grounding scenarios and deriving a formula for the relation between the volume of deformed structure and the energy absorption (like the Minorsky formula). Moreover, the damage statistics is used to illustrate that the damage length divided by ship length is a function of the ship size. This observation is not in agreement with current regulations where bottom damage is proportional to ship length. The scaling theory is then used to explain that large ships experience longer relative damages than small ships. Major conclusions of the study are that the quality of future damage records should be improved, that various requirements and rules involving bottom damage may need to be revised, and that a method has been proposed for ranking ships according to their crashworthiness in grounding accidents. [S0892-7219(00)00103-5]

A COMPARATIVE STUDY OF CAM MOTIONS FOR HIGH-SPEED SEMI-RIGID FOLLOWER CAM SYSTEMS

1988 ◽  
Vol 12 (3) ◽  
pp. 121-128 ◽  
Author(s):  
P.S. GREWAL ◽  
W.R. NEWCOMBE
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Poor Performance ◽  
Performance Criteria ◽  
Vibrational Response ◽  
High Speeds ◽  
Speed Performance ◽  
Cam Profile ◽  
Torque Values ◽  
Profile Errors

A study is presented on the comparison of all the popular cam motions based on a refined dynamic model which takes into account the effects of cam profile errors and most of the important factors that influence the dynamic performance for a semi-rigid follower cam system. A stochastic model is developed to simulate the input signal resulting from the cam motion, including the deviations due to profile errors. The performance criteria comprise the vibrational response at the follower and the dynamic characteristics at the cam. It has been established that, at high speeds, it is not the vibrational behaviour, but the follower tendency to jump and the maximum contact force and cam torque values which determine the dynamic performance. The Modified-Sine, Simple Harmonic and 3-4-5 Polynomial motions have been shown to exhibit superior high speed performance compared to that of the popular Cycloidal and Modified Trapezoidal motions. Higher-order Polynomial motions give very poor performance at high speeds.

A Versatile Acceleration-Based Cam Profile for Single-Dwell Applications Requiring Cam-Follower Clearance During Dwell

2011 ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Velocity Function ◽  
Gas Leakage ◽  
Poppet Valve ◽  
Equation Solving ◽  
Cam Follower ◽  
Cam Profile

Presented in this paper is a cam motion program suitable for single-dwell cam-follower systems with built-in clearance between the cam and follower during the dwell portion of the cycle. This makes the motion program particularly well-suited to applications such as valve trains in internal combustion engines in which cam-follower clearance is necessary to ensure proper seating of a poppet valve, preventing gas leakage across the seal. The motion program for the cam follower is derived from the follower acceleration function so that designers can control the ratio of the magnitudes of positive and negative accelerations. This provides cam designers more control over the cam-follower interface force and therefore more control over factors such as cam wear and the potentially destructive phenomenon known as “follower jump.” Included in the motion program is asymmetric rise and fall that allows different times for these events. The follower acceleration is designed to be smooth enough to provide continuous jerk throughout the actuation phase, thereby tending to reduce undesirable residual vibrations. The motion program used to close and open the clearance gap is derived from a velocity function, allowing more control of follower inertia during the important clearance closing event. The motion program is presented in a form appropriate for implementation in standard engineering equation-solving software, giving the cam designer easy control over important parameters in high-speed cam-follower systems.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

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