Slider-crank Mechanism Research Articles

Synthesis of a variable stroke slider crank mechanism for a reciprocating internal combustion engine

Synthesis of a variable stroke slider crank mechanism for a reciprocating internal combustion engine

On nonlinear dynamics behavior of an electro-mechanical pendulum excited by a nonideal motor and a chaos control taking into account parametric errors

This study analyzes a nonlinear system with a crank–shaft–slider mechanism linked to a pendulum. The crank is powered by a DC motor that moves horizontally the pendulum pivot. The speed of the motor is influenced by the pendulum dynamics, reason for calling the system as nonideal. In literature, the vibration of the pendulum support by a crank–shaft–slider is generally considered as harmonic what neglects the real complexity of the mechanism. It is also common, for the crank speed or the excitation frequency to be considered constant, so a unique degree-of-freedom can take place. The novelty in this research is the analysis of the feedback effect of the pendulum over the crank speed and the complexity of crank–slider mechanism without approaching to a harmonic motion. Different types of motion occur as oscillations, rotations, and chaos. Results with different initial conditions are worked out and basins of attractions plotted. Chaos was obtained when small variations of parameters are made. The methods of analysis include phase portraits, time histories, bifurcations diagrams, and basins of attraction. The verification of chaotic phenomena is performed through the 0–1 test. By the end, the feedback control is applied using the method of Tereshko by altering the energy of the chaotic system, leading the pendulum to a limit cycle.

Quasi-dynamic and thermal analysis of a diesel engine piston under variable compression

Due to ever increasing demand for high speeds of automobiles and high gas loads, the piston of an IC engine is subjected to large thermal and structural stresses. The authors have therefore embarked upon evaluating the stresses induced in the piston and also study the effect of compression ratio on it. An experimental setup consisting of a computerized variable compression ratio diesel engine test rig with necessary instrumentation was established. A comprehensive load history in terms of pressure vs. crank angle(p-Θ) diagram and (pressure vs. gas volume), speed, fuel and air consumption rates, turning moment etc., were obtained at compression ratios of 16.5,17.5 and 18.5 from the experimentation. Part one is heat transfer analysis for evaluating the thermal boundary conditions like heat transfer coefficients and heat flux. Further the mean temperature of the working fluid is also obtained from thermodynamic analysis. Part two is dynamic analysis by using the equations of equilibrium for slider-crank mechanism. Part three is stress analysis using finite element method coupled field at critical angles of crank rotation where either inertia forces or wrist pin forces are maximum. The results in the form of von-mises stresses and deformation are presented. Further, factor of safety is evaluated. It was observed that increasing compression ratio has an appreciable effect on the stresses. It was interestingly observed that the mean temperature of gases is higher at compression ratio of 17.5. Stresses developed due to differential thermal expansion in the piston form a significant part of the total stresses.

Application of Lagrange equations in the analysis of slider-crank mechanisms

Application of Lagrange equations in the analysis of slider-crank mechanisms

Reliability analysis of motion mechanism under three types of hybrid uncertainties

Hybrid reliability analysis of motion mechanism, in which the inputs contain both random variables and interval variables, is investigated in this paper. Firstly, the hybrid uncertainty is divided into three categories. In the first category, the inputs that include both random variables and interval variables are considered. In the second category, the inputs that include random variables with interval distribution parameters are considered. In the third category, the inputs that include both random variables with interval distribution parameters, and interval variables are considered. The above three types of uncertainties outline the general situation of hybrid uncertainties. In order to achieve the reliability analysis of motion mechanism under the above three hybrid uncertainties, this paper presents a method of combining the Poisson's assumption-based first passage method and a double loop iterative algorithm. The specific calculation process is described in detail by a numerical example. Simultaneously, the accuracy and efficiency of the proposed is also shown and discussed by comparing the Monte Carlo simulation (MCS) results in this numerical example. Finally, the proposed method is applied to two practical engineering examples, a crank slider mechanism and a rack-and-pinion steering linkage.

Pin-slot clearance joints in multibody systems

The pin-slot joint is one of the most commonly used form of kinematic pairs, which with clearance will have a significant effect on the motion and dynamic response of multibody systems. In this study, the multibody system with a pin-slot clearance joint is modeled and the kinematic and dynamic effects are studied. Firstly, the generalized coordinate systems were established and the motion constraint equations of the pin-slot clearance joint were derived. Then, the theories of kinematics and dynamics were used to deduce equations of motion and dynamics. Finally, using slider-crank mechanism as the application example, the simulation study of the multibody system with a pin-slot clearance joint was carried out. The results show that there is an impact phenomenon in the moving process of the end slider, and with the increase of the slot angle, the impact phenomenon is earlier and the impact strength is weaker, however, with the increase of the slot value, the time when the impact phenomenon appearing doesn't change while the impact strength increasing. Furthermore, the maximum displacement of the end slider reduces with the increase of the slot value while the maximum value of driving torque doesn't change and the fluctuation of driving torque increased.

Partition method and experimental validation for impact dynamics of flexible multibody system

The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields: multibody system dynamics (MBS) and computational solid mechanics (CSM). Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed: the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effective formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.

Topology optimization of members of flexible multibody systems under dominant inertia loading

The topology optimization of members of flexible multibody systems is considered for energy-efficient lightweight design, where the gradient calculation has an essential role. In topology optimization of flexible multibody systems, where the function evaluations are very time consuming, the gradient information is necessary to accelerate the optimization process. Different approaches have been introduced and tested for the gradient calculation in the fully coupled topology optimization of flexible multibody systems. However, the computation and implementation costs of these methods are high, which limits the optimization size and the possible number of design variables. In this work, we present a modified gradient calculation based on the equivalent static load (ESL) method, which combines the time efficiency of gradient calculation of the ESL method with the higher accuracy of gradient calculation in the fully coupled methods. This modified approach, which takes into account the linear dependencies of inertial loads on acceleration, is tested on the application example of a flexible slider-crank mechanism, and the results are compared with the weakly coupled ESL method and a fully coupled optimization where gradients are calculated using the adjoint variable method.

Effect of the reciprocating mass of slider-crank mechanism on torsional vibrations of diesel engine systems

The torsional vibration phenomenon in the running gear of reciprocating engine systems isusually dealt with by considering a series of constant inertias connected by sections of massless shafting. However in reality, a slider crank mechanism is a vibrating system with varying inertia because the effective inertia of the total oscillating mass of each crank assembly varies twice per revolution of the crankshaft. Large variations in inertia torques can give rise to the phenomenonof secondary resonance in torsional vibration of modern marine diesel engines which can not be explained by conventional theory incorporating only the mean values of the varying inertias. In the past associated secondary resonances and regions of instability tended to be dismissed by most engineers as interesting but of no importance. The situation changed in recent years since there is evidence of the existence of thesecondary resonance effects which could have contributed to a number of otherwise inexplicable crankshaft failures in large slow speed marine engines. The cyclic variation of the polar moment of inertia of the reciprocating parts during each revolution causes a periodic variation of frequency and corres ponding amplitude of vibration of reciprocating engine systems. It also causes an increase in the speed range over which resonance effects are experienced and only a partial explanation of the behaviour of the systems has been worked out. It is impossible to avoid these instabilities by changes in thedesign , unless of course the variations in mass and spring constant can be made zero. In the present paper a critical appraisal of the regions of instability as determined from the equation of motion which takes into account variation of inertia is given. The motion in the form of complex waveforms is studied at different speeds of engine rotation. A comparison of theoretical results with Goldsbrough’s experimental resultsand Gregory’s analysis is included.

Analysis on dynamic precision reliability of high-speed precision press based on Monte Carlo method

The high-speed precision press is used widely in modern industrial production, particularly in the production of precision parts. The dynamic repeated precision of bottom dead center (BDC) measurement not only affects the quality of stamped parts, but also determines the service life of the pattern. In this paper, the influence of machining error, elastic deformation and joint clearance on the reliable precision reliability of a slider was analyzed. A method of analyzing instantaneous dynamic BDC press precision is presented. Finally, the reliability of the press is evaluated using time-varying reliability in the nominal force travel range. Taking the JF75G-300 high-speed press as an example, the motion precision reliability model of the crank slider mechanism is developed; the BDC position of the press under different speeds is simulated using the Monte Carlo simulation method, and experiments are conducted on the BDC position of the punch with no load. Experimental results and simulated results are similar, demonstrating feasibility of the proposed method.

Design of a Parallel Actuated Exoskeleton for Adaptive and Safe Robotic Shoulder Rehabilitation

Powered exoskeletons can facilitate after-stroke rehabilitation of patients with shoulder disabilities. Designs using serial mechanisms usually result in complicated and bulky exoskeletons. This paper presents a new parallel actuated shoulder exoskeleton that consists of two spherical mechanisms, two slider crank mechanisms, and a gravity balancing mechanism. The actuators are grounded and placed side-by-side. Thus, better inertia properties can be achieved while lightweight and compactness are maintained. An adaptive mechanism with only passive joints is introduced to compensate for the exoskeleton–limb misalignment and size variation among different subjects. Linear series elastic actuators (SEAs) are proposed to obtain accurate force and impedance control at the exoskeleton–limb interface. The total number of force sensors and actuators is minimized using the adaptive mechanism and SEAs. An exoskeleton prototype is shown to provide bidirectional actuation between the exoskeleton and upper limb, which is required for various rehabilitation processes. We expect this design can provide a means of shoulder rehabilitation.

Optimum synthesis of oscillating slide actuators for mechatronic applications

Abstract The oscillating-slide inversion of the slider-crank mechanism, commonly symbolized RPRR, is widely used to convert the displacement of an input linear motor (either electric, hydraulic or pneumatic), into the swing motion of a rocker. This paper discusses the optimum kinematic synthesis of the centric RPRR mechanisms for prescribed limit positions, while simultaneously satisfying either (i) minimum deviation from 90° of its transmission angle, (ii) maximum mechanical advantage, or (iii) linear correlation between the input- and output-link motions. To assist practicing engineers, step-by-step design procedures, together with performance charts and parametric design charts are also provided in the paper. Highlights Optimum kinematic solutions of the RPRR oscillating slide actuators are discussed. Design objectives are transmission angle, mechanical advantage and uniform motion. Short rocker and long rocker solutions are shown to exist for each of these problems. Bivariate parametric design charts and performance charts are provided. Simple step-by-step design procedures are also described.

Modeling and simulation of planar multibody systems considering multiple revolute clearance joints

This paper presents a general procedure for dynamic modeling and simulation of planar multibody systems considering multiple revolute clearance joints. The normal contact force is evaluated by a hybrid continuous contact force model, established on the base of the Lankarani–Nikravesh (L–N) model and the elastic foundation model. The LuGre friction law is employed to describe the tangential effect. The effectiveness of the presented methodology is demonstrated through the comparisons with the MSC ADAMS software simulation results of a slider–crank mechanism with clearance joints. Then, the system behavior affected by dynamic interaction of three revolute clearance joints is analyzed and some kinds of 27 combination modes are presented. Additionally, a comprehensive analysis of the system responses in a wide range of dynamic simulation parameters is conducted to find out some inner rules existed in the mechanical system with revolute clearance joints. Results show that there exists a strong dynamic interaction between different clearance joints, indicating that all joints should be modeled as imperfect to achieve a further understanding of multibody system behavior. Also, the clearance joint nearer to the input link is found to suffer more serious contact effects, require more input torque and cost longer computational time. Furthermore, the system dynamics relies on many factors, even a small change of which may lead to different system responses, changing from periodic to chaotic and the other way around. In addition, several characteristic values have been captured from the simulation results, which need to be paid more attention in use.

Multibody contact dynamics on mechanisms with deep groove ball bearing joints

The dynamics of ball bearings are important to fatigue breakage, dynamic performance and motion precision of mechanisms connected by ball bearings joints with multi-clearances. In this study, a new method is proposed for multibody dynamics analysis on mechanisms under the effects of radial internal clearances and impact of balls/cage pockets interactions of ball bearings. Including balls/rings interactions and balls/cage pockets interactions, the three dimensional dynamics models of the crank slider mechanism are established and calculated by generalized-α algorithms on the basis of Hertzian contact theory and penalty function method. The rules of eccentric trajectories of inner and outer ring center for one ball bearing joint are verified with the results calculated by XU’s references. The results of dynamic errors, motion trajectories, dynamic forces are achieved under different speeds, radial clearances and number of ball bearings. The speeds and radial clearances are critical to the dynamic performances and motion precision of mechanisms, especially the number of ball bearings. The number of ball bearings is important to impact force and motion stability of the mechanism.

REMOTE CONTROL OF THE MECHATRONIC REDESIGNED SLIDER-CRANK MECHANISM IN SERVICE

Slider-crank mechanisms are used in many machines where there is a need to transform rotary motion into translation, and vice versa. Implementation of the control into a mechanical assembly of the slider-crank mechanism offers a wide range of applications of such controlled mechanism in mechatronic systems. This paper shows an example of the remote control of the angular velocity of the crank in a mechatronic redesigned slider-crank mechanism in order to achieve the desired motion of the slider. The remote control is achieved over the Internet connection and the appropriate software which is executed in the user’s internet browser. The aim of this paper is to present the applied control algorithm as well as to explain advantages of the possibility to remotely run a mechatronic redesigned slider-crank mechanism in service. This is done through an example of using a controlled slider-crank mechanism in a remote laboratory experiment.

Development and performance evaluation of a guided horizontal conveyor rice harvester

A guided horizontal conveyor rice harvester that uses slider-crank mechanism to drive the cutter bar was designed and constructed. Most Nigerian farms are segregated and this makes it difficult to make use of combine harvester as mechanical means of harvesting. Essential parts of the harvester are cutter bar, conveyor, transmission system and crop reel. The machine constructed was operated and tested on the rice field of National Cereals Research Institute (NCRI), Moor plantation, Ibadan, to evaluate the performance of the machine. A 22 x 3 factorial experimental design with two replicates was used to analysis the effect of engine speed (1200, 1400 and 1800rpm), ecology (irrigated and rainfed-lowland) and moisture content (18.3% and 21.2%) on field capacity, field efficiency, cutting efficiency and operation loss. The test result revealed that moisture content had a significant effect on both the cutting efficiency and operation loss of the machine while the ecology had a significant effect only on the field capacity and field efficiency. At moisture content of 21.2%, the average cutting efficiency was higher with the highest value of 97.2% at 1200rpm. At moisture content of 18.3%, lower operation losses were recorded. The lowest average operation loss of 23.9% was recorded against the 1800rpm. The rainfed-lowland ecology gave a higher field capacity and efficiency. The highest field capacity of 0.0525ha/hr and field efficiency of 49.1% was recorded at 1400rpm. Maximum cutting efficiency of 97.2% was recorded at 1200rpm and 21.2% moisture content, and, lowest operation loss at 1800rpm and 18.3% moisture content.Keywords: Guided rice harvester, horizontal conveyor, slider-crank, cutter bar

Series elastic actuation of an elbow rehabilitation exoskeleton with axis misalignment adaptation.

Powered exoskeletons can facilitate rehabilitation of patients with upper limb disabilities. Designs using rotary motors usually result in bulky exoskeletons to reduce the problem of moving inertia. This paper presents a new linearly actuated elbow exoskeleton that consists of a slider crank mechanism and a linear motor. The linear motor is placed beside the upper arm and closer to shoulder joint. Thus better inertia properties can be achieved while lightweight and compactness are maintained. A passive joint is introduced to compensate for the exoskeleton-elbow misalignment and intersubject size variation. A linear series elastic actuator (SEA) is proposed to obtain accurate force and impedance control at the exoskeleton-elbow interface. Bidirectional actuation between exoskeleton and forearm is verified, which is required for various rehabilitation processes. We expect this exoskeleton can provide a means of robot-aided elbow rehabilitation.

Delta Parallel Robot Based on Crank-Slider Mechanism

A three-degree-of-freedom Delta parallel manipulator driven by a crank-slider mechanism is proposed. In Cartesian space, a gate-shaped curve is taken as the path of the pick-and-place operation, combining with the inverse kinematics theory of the Delta robot, and a mathematical model of robot statia force transmission is established. The force and the output torque of the robot-driven joint are taken as the main performance indexes, and the value of the crank-slider mechanism applied to Delta robot is further measured. The simulation results show that the delta robot driven by the crank slider mechanism can reduce the force and output torque of the driving joint during the picking and discharging operation, and has good practical application value.

Interface reduction methods for mechanical systems with elastohydrodynamic lubricated revolute joints

In this contribution, three different reduction methods for elastic structures with lubricated interfaces are presented and compared with each other. While for the first two methods, classical reduction strategies from component mode synthesis are applied, for the third method, a dual reduction basis is used, consisting of vibration modes of the free floating structure, attachment modes and residual modes. Within this new dual approach, it is shown how the residual modes can be obtained by applying pressure distributions of analytical solutions of the hydrodynamic equations. The described methods are compared for two classical simulation example—for a one-sided elastohydrodynamic lubricated joint of a slider–crank mechanism in a floating frame of reference formulation as well as for an elastic rotor in a flexible journal bearing.

Analysis of loaded characteristics of helical curve face gear

As a new gear pair, the helical curve face gear pair have not been widely applied as normal face gear. It can be used to substitute crank-slider mechanism to achieve variable transmission ratio and improve the structure and characteristics to some extent, such as grinders, planers and so on. The mathematical model of the helical curve face gear pair and the tooth contact analysis are necessary for the theoretical analysis of this gear pair. Based on the theory of gear meshing and coordinate transmission, the meshing equations for non-circular gear contacting with helical curve face gear without misalignment are obtained. On the basis of Hertz's theory, the principal curvatures at contact point are represented. And the contact area on every tooth and the half cycle of helical curve face gear have been established separately. As well as the contact stress on every tooth and half cycle of helical curve face gear. However, there may be misalignment during the meshing of this gear pair, this paper also covers the contact path and the functions of transmission errors with misalignment, includes the comparison of helical curve face gear and straight curve face gear. The developed theories for complex tooth surface are verified by experiment. These analysis show the contact characteristics of this gear pair during the meshing process and provide the theoretical support for further analysis and application of helical curve face gear pair.