Slider Mass Research Articles

Impact of 3D-printed laboratory equipment in vibrations and controls courses on student engineering identity, motivation, and mindset

This paper describes the implementation of innovative 3D-printed laboratory equipment linked to inquiry-based learning activities designed to improve learning, increase engineering identity and motivation, and foster a growth mindset in students taking undergraduate level mechanical vibrations courses, control theory courses, and associated laboratories. These innovative designs create new opportunities for hands-on learning, are low-cost, portable, and can be adapted for use in multiple science and engineering disciplines. The learning activities are based on the POGIL model, which has been used across a variety of disciplines including engineering. We describe the features of three separate devices (spring-connected sliding carts, compliant parallel arms with fixed-free ends and a slider mass, and a pendulum with variable tip load) implemented using a quasi-experimental approach with 510 duplicated students across three semesters during the COVID-19 pandemic in multiple lecture courses and laboratory sections. We also present an assessment of impact based on descriptive statistical analyses of survey data for student-reported learning gains and pre-post paired comparison tests on validated instruments measuring perceptions of engineering identity, engineering motivation, and growth mindset. Further, we conducted a student focus group and include salient instructor observations. Results show most students participating in the learning activities using these devices report that it supported their learning “a lot” or “a great deal.” In addition, on six of seven surveyed learning outcomes, most students reported feeling confident enough to complete them on their own or even teach them to someone else. Our data did not show a measurable impact on engineering identity, engineering motivation, or growth mindset, though it does suggest further investigation is merited.

The Energy Recovery Effect of Wave Energy Utilization System under the Rolling Motion of Ships

In order to realize the utilization of wave energy on ships, this study proposes a wave energy utilization system mounted on ships. The wave energy utilization system can transform wave energy into electric energy. The working principle and installation mode of the system are introduced in detail, and the motion model of the system on the ship is established. The motion equation of the system is solved by the Newmark-β method, and the influence of different slider masses (150–500 kg) and different radius of sliding rail (7–15 m) on the energy recovery performance of the system is studied. The data simulation shows that under a certain radius of the sliding rail, there is a slider mass that makes the system achieve the best energy collection effect. With the increase of the radius of the sliding rail, the slider mass corresponding to the best energy recovery performance of the system also increases. In addition, the energy recovery performance of the system under actual sea conditions is simulated, and the research shows that the system can continuously output power.

Theoretical and experimental investigation of a bi-stable piezoelectric energy harvester incorporating fluid-induced vibration

Vibration-based piezoelectric energy harvesting has potential applications in the effective energy supply for sensors and communication devices. To address the need to increase the levels of harvested energy and adjust the low-frequency bandwidth, we design a bi-stable piezoelectric energy harvester (BS-PEH) incorporating fluid-induced vibration, which only needs to simply modify equipment that exists fluid tank. A theoretical model based on fluid equivalence is established to construct the dynamic equation and electromechanical coupling equations of the proposed BS-PEH. Experimental results investigate the validity of the theoretical model, and the comparison with the existing literature also shows the superiority in power density. Then the sensitivity of the averaged power to uncertain resistive load is given and analyzed, and the improvement of energy harvesting capacity by bi-stable structure is discussed. Subsequently, the parametric study for design parameters reveals the influence of each parameter on the output characteristics of BS-PEH and gives the configuration of optimizing energy harvesting. Moreover, the proposed BS-PEH is easy to design, and a higher energy harvesting efficiency can be achieved by simply changing the accessories, in which modifying the slider mass can make the output power reach 81mW.

Modelling and analysis of the nonlinear string-mass structure of the vibration absorber

ABSTRACT In this paper a nonlinear string-mass structure of the vibration absorber is analyzed. This structure is convenient to be installed in vibration damping systems of high buildings for their protection in the case of earthquake. The considered string-mass structure contains a translator movable mass connected with two strings. Due to nonlinear geometric properties of the system the motion of the mass is described with a strong nonlinear second order differential equation. In the paper the approximate procedure for solving of the nonlinear equation of motion is developed. Based on the solution the influence of the string preloading force, slider mass and friction force on the vibration property of the string-mass system is investigated. It is concluded that variation of the preloading string force may be applied as a control parameter for vibration absorption and as the regulator of vibration decay time.

Study on capture power of the sealed-buoy wave energy converter in low energy flow density area

In order to achieve the conversion of the wave energy into electrical energy in low energy flow density sea areas in this paper, the capture power of the sealed-buoy wave energy converter (SBWEC) was investigated by dynamics methods of rigid bodies based on the hydrology data of Shandong Peninsula. The effect of buoy diameter on the response amplitude operator (RAO) was studied using frequency domain analysis method. The effect of buoy diameter on the instantaneous capture power and the effect of mooring angle on the pitch time domain response were studied using time domain analysis method. Results show that the pitch RAO is increased by 10.5 times from 8°/m to 93°/m with the decrease in buoy diameter. The maximum pitch time domain response and capture power are obtained in the SBWEC with the diameter 15m, mooring angle 45° and the slider mass 40 Kg. It is derived that the average capture power and wave energy conversion efficiency are 44.1 KW and 54.44% for the SBWEC in low energy flow density sea areas. Then, the relevant research results provide some reference for the design and utilization of wave energy converter in low energy flow density sea areas.

A Vibration Absorption Method for Alleviating Impact of the Flexible Robotic Arm

Impact may excite intense vibration responses of the flexible robotic arm and thus deteriorate its working performance. A vibration absorption method is put forward to alleviate impact influence of the flexible robotic arm. To dissipate the impact vibration energy, a slider mass–spring–dashpot mechanism is used as a vibration absorber and attached to the flexible robotic arm. Internal resonance is sufficiently utilized to provide a bridge for the transfer of impact vibration energy between the flexible link and the absorber via nonlinear coupling. In the presence of damping of the absorber, the impact vibration energy of the flexible link can be effectively migrated to and dissipated by the absorber. Numerical simulations and virtual prototype simulations verify its effectiveness and feasibility in alleviating impact vibration of the flexible robotic arm undergoing a collision.

Dynamic analysis and controller design for a slider–crank mechanism with piezoelectric actuators

Abstract Dynamic behaviour of a slider–crank mechanism associated with a smart flexible connecting rod is investigated. Effect of various mechanisms' parameters including crank length, flexibility of the connecting rod and the slider's mass on the dynamic behaviour is studied. Two control schemes are proposed for elastodynamic vibration suppression of the flexible connecting rod and also obtaining a constant angular velocity for the crank. The first scheme is based on feedback linearization approach and the second one is based on a sliding mode controller. The input signals are applied by an electric motor located at the crank ground joint, and two layers of piezoelectric film bonded to the top and bottom surfaces of the connecting rod. Both of the controllers successfully suppress the vibrations of the elastic linkage. Highlights Dynamic behaviour of a slider–crank mechanism associated with a smart flexible connecting rod is investigated. Effect of various mechanisms' parameters including crank length, flexibility of the connecting rod and the slider's mass on the dynamic behaviour is studied. Two control schemes are proposed for elastodynamic vibration suppression of the flexible connecting rod and also obtaining a constant angular velocity for the crank. Controllers are based on feedback linearization approach and sliding mode controller.

A thermal boundary control method for a flexible thin disk rotating over critical and supercritical speeds

In practice a rotating flexible thin annular disk has to be operated at low speed, because three types of dynamic instabilities inevitably occur around critical and supercritical speeds, namely: aeroelastic, parametric and thermoelastic. The rotating disk is clamped and driven by a drive shaft attached to the disk inner edge. The external action of the flowing surrounding air causes the aeroelastic instability; a slider mass–damper–spring–friction moving load causes parametric instability; and disk/slider interface friction heat can cause thermoelastic instability. A thermal boundary control method is used to induce disk thermal membrane stresses utilizing drive shaft temperature increments to stabilize these dynamic instabilities. Fundamental investigations are made of disk temperature distribution, thermal stress, natural frequency, dynamic stability and steady state amplitude to validate and demonstrate the viability of the new control method. The thermal boundary control method offers valuable opportunities for rotating disk applications operating over critical and supercritical high speeds with high efficiency.

Theoretical Analysis of Flying Characteristics for Air-Helium Filled HDD

This paper presents the flying characteristics of air-helium filled hard disk drive for a self-acting two rails flat slider bearing. Numerical scheme based on the finite difference with multi-grid multi-level technique were implemented for the ultra-low flying height sliders. The characteristics of air-helium filled HDD have been examined in this research work. The results shown that the change of flying height is significantly for various fraction of air-helium filled, at various operating conditions such as temperature velocity and mass of slider. Increase of velocity, flying height increase. Increase both the temperature and the mass load, flying height decrease. Increasing of fraction in helium gas, the flying height decreases rapidly for 40% to 60 % of fraction in helium filled. The flying height for air-helium filled magnetic flat slider head equal to 1.3 nm at trailing edge with mass load 12 mN and velocity 20 m/s. The spacing for helium filled hard disk drive is lower than 3 nm when compared with conventional air filled hard disk drive.

Theoretical Method Research on a MEMS Safety and Arming Device

With the intelligent development of small-caliber ammunition, the overall size of the fuze is compressed. In this paper, a theoretical method-energy statistical method has been proposed according to the MEMS S&A device. Taking the slider mass, micro-spring stiffness, latch mechanism size, and initial offset distance into account, the conversion relationship among each part of energy in the process is obtained. For an existing structure of MEMS S&A device, known parameters are utilized to reverse the overload value at arming condition. The ANSYS/LS-DYNA finite element analysis software is used for simulation analysis, thereby confirming the feasibility of theoretical calculations. Also, theoretical calculation error ε is obtained, which to be 0.7%. Energy statistical method and simulation analysis serve as theoretical references for the design of the MEMS S&A device.

Dynamic snapping of a suddenly loaded elastica with fixed end slopes

In this paper we study the dynamic snapping of an elastica with fixed end slopes. Both ends of the elastica are clamped, with one fixed in space and the other allowed to slide along a linear track. An edge thrust is applied suddenly on the sliding clamp, causing the elastica to undergo a snap-through jump. This setup can be used as a bistable device. The interest of this paper is to determine the critical value of the suddenly applied edge thrust causing snap-through, termed dynamic snapping load. With use of deformation potentials, the equations of motion of the elastica-slider assembly are rearranged, taking into account the effects of both the slider mass and damping. Finite difference method is adopted to discretize the resulted equations. In order to ensure the convergence of the numerical scheme, a linearization approach has to be adopted when the slider mass is non-zero. It is observed that for the setup studied in this paper, the dynamic snapping load is about 90% of its static counterpart. The viscous damping associated with the end slider in general has a favorable tendency of raising the dynamic snapping load. Somewhat unexpectedly, although the slider mass affects the transient response of the elastica-slider assembly significantly, it has no effect on the dynamic snapping load.

Optimal Control of Servo Actuators with Flexible Load and Coulombic Friction

Feedback control and optimal control techniques are discussed for servo actuators that are widely used in micro-electro-mechanical systems (MEMS) technology of manufacturing. A typical servo actuator is the voice-coil motor used for actuating micro machine tool axes, bonding machines and hydraulic/pneumatic valve drives. State-of-the-art feedback control techniques are deficient with regard to high precision positioning and process duration. To improve on this deficiency, optimal control techniques are applied to a dynamical model of servo drives. Since Coulombic friction is modeled as sign function depending on the sign of the velocity, the optimal control problem belongs to the class of nonsmooth optimization problems. Time-optimal controls are computed for a variety of control bounds. It is shown that time-optimal controls are of bang-bang type and reduce transfer times considerably. Switching times are optimized directly by appropriate nonlinear programming methods. Optimal controls are studied under state constraints that limit deviations in positions and velocities of the slider and load mass. The goal of reducing such deviations can also be achieved by energy-optimal controls with larger transfer times. Realtime implementations of the computed optimal control signals indicate an excellent agreement between predicted trajectories and experimental results.

Nonlinear Model Based Estimation of Rigid-Body Motion Via an Indirect Measurement of an Elastic Appendage

In this paper, we develop and implement a nonlinear model based procedure for the estimation of rigid-body motion via an indirect measurement of an elastic appendage. We demonstrate the procedure by motion analysis of a compound planar pendulum from indirect optoelectronic measurements of markers attached to an elastic appendage that is constrained to slide along the rigid-body axis. We implement a Lagrangian approach to derive a theoretical nonlinear model that consistently incorporates several generalized forces acting on the system. Identification of the governing linear and nonlinear system parameters is obtained by analysis of frequency and damping backbone curves from controlled experiments of the decoupled system elements. The accuracy of the proposed model based procedures is evaluated and its results are compared with those of a previously reported point cluster estimation procedure. Two cases are investigated to yield 1.7% and 3.4% errors between measured motion and its model based estimation for experimental configurations, with a slider mass to pendulum frequency ratios of 12.8 and 2.5, respectively. Motion analysis of system dynamics with the point cluster method reveals a noisy signal with a maximal error of 3.9%. Thus, the proposed model based estimation procedure enables accurate evaluation of linear and nonlinear system parameters that are not directly measured.

The transverse runout of a rotating flexible disc under stationary sliders

The governing equation of a rotating flexible disc under stationary sliders is modelled under consideration of the initial transverse runout of the disc. Natural frequency and stability of the system is studied and checked, and steady-state response is obtained. The effects of system parameters on the steady-state amplitude of the sliders are analysed and resonance induced by the sliders is discovered. The decrease of the number of nodal diameters of the initial transverse runout and slider mass, and the increase of disc damping, slider damping, and natural frequency and friction force at the disc—slider interface, can be used to suppress the amplitude.

New approaches to in-contact recording system for high-density recording

In this paper, we present some new technologies for in contact systems to achieve higher linear recording density for Hard-Disk Drives (HDDs). An important result for the in-contact slider was obtained, i.e., available slider mass extends to several milligrams which indicate that a conventional process technology can be applied. As a result of new pad design and lubricant materials to enhance attractive force between the head and disk surfaces, small mechanical spacing of 3 nm was confirmed. The heads with a critical load to achieve a zero-wear showed excellent wear performance. A prototype of contact HDD was well functioned on the head tracking.

A new approach to roughness-induced vibrations on a slider

In the past, roughness effects were included in models by using various friction laws. In contrast, this study deals with simple Poisson impact and Coulomb friction laws on multiple concurrent contacts between geometrically random rough surfaces and their effect on the slider's roughness-induced vibrations. The closed-form solutions derived here relate roughness-induced vibrations to the surface roughness, slider mass, slider load, slider dimensions, relative sliding speed, and the coefficient of restitution. Wear influences were studied by simulating random rough surfaces with multiple concurrent contacts. Contrary to expectations we found that random roughness can induce slider vibrations of distinct frequencies. We found a good agreement between the results of the studied models and the experiments. The closed-form solution was found to be suitable for estimating the roughness-induced vibration frequencies of a hard-disk drive's writing/reading head and those of a car-brake's pad (known as squeal-noise).

Improved Micro-EDM Miniaturized Device Using Differential Reciprocating Driving Method

A miniaturized Electrical Discharge Machine (EDM) device based on ultrasonic motor has been developed to machine micro-holes in narrow space. In this mechanism, the electrode is driven without need of electrode holder, so that the mass and inertia of slider are greatly smaller, and feeding frequency of electrode can be raised compared to the conventional miniaturized EDM devices. This is a significant improvement that the electrode’s driving means varies from plane driving to line driving. Because of its advantage of compact size, the miniaturized EDM device can be fixed on robot. Differential Reciprocating Driving Method (DRDM) for EDM electrode is proposed. Feeding resolution of electrode reaches 0.5μm in stepping style, while resolution reaches 40nm in differential reciprocating style, and all above characteristics create preconditions for micro EDM machining. The holes with figures of Φ90μm inclined circle and inclined Y have been machined.

Characteristics of the Contact Force between the Head-Slider and the Disk in a Magnetic Disk Drive

This paper deals with the characteristics of the contact force when the head-slider collides with the disk in a magnetic disk drive. At first, the analysis to examine the characteristics of the contact force was conducted. It showed that the factors such as the slider mass, the loading force of the slider, and the pitching-angle of the slider have a strong influence. Then, the experiments by the parameter survey to examine the relation between the above factors and the contact force were conducted. The wave source analysis was used for the contact force experimentally. The analysis and the experiments show the characteristics that the contact force is approximately proportional to the loading force of the slider, and proportional to the root of the slider mass and the pitching-angle of the slider.

接触する微小２平面間に作用する凝着力 寸法，雰囲気および表面濡れ性の影響

Adhesion force, exactly standing for pull-off force, between tiny flat surfaces was measured. Adhesion force that acts between two mating surfaces becomes dominant factor in microscopic mechanisms. Sometimes it becomes larger than the weight of the moving part and restricts its motion. This paper describes the measurement method of adhesion force first. A silicon slider (chip) is placed on an inclined guide that is vibrated by a voice coil motor, and the adhesion force is calculated from the slider's mass and the critical acceleration that the slider begins to slide down. It was found that the adhesion force is ideally proportional to the nominal contact area in vacuum though it is not proportional in air. Also, the effect of the wettability of the surface on the adhesion force was made clear. These results suggest that the elimination of water capillary from interface of the mating surfaces is important to obtain steady motion of the mechanism.

Dynamics for Micromachined Mother Ship Negative Pressure Slider Bearings With an Integrated Microsuspension Mechanism in Proximity Magnetic Recording

This paper describes head/disk interface dynamics for micromachined mother ship negative pressure slider bearings with an integrated microsuspension mechanism that we proposed, at steady-state flying in proximity magnetic recording. The authors first indicated the analytical model for air bearing dynamics of mother ship slider mechanisms, and the advantages of the mechanisms were discussed from the dynamics points of view, compared with conventional flying head slider mechanisms. Dynamic design considerations and optimization for micromachined mother ship negative pressure slider bearings with an integrated microsuspension mechanism were also investigated. Finite element simulation for the stiffness analysis of a microsuspension mechanism was carried out and the design optimization for low stiffness gimbals was studied. Furthermore, the effects of slider mass ratio and slider car film stiffness ratio of a secondary slider to a primary slider on mother shipslider dynamics were analyzed numerically. Considering those numerical simulationresults, system optimization for sliders as well as microsuspension gimbals was established to achieve head/disk interface reliability in high density proximity magnetic recording.