Micro-droplet generation is related to liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic micro-droplet generation is controlled by a solenoid valve being briefly turned on, so that high pressure gas enters the liquid reservoir, forming a gas pressure pulse waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each ejection, P(t) is acquired by a high speed pressure sensor, and the ejection state is obtained by machine vision methods. A prediction model based on BP neural network is established, with P(t) as input and the droplet ejection state as output. Experiments show that the BP neural network can predict the number of droplets with an accuracy higher than 99%. It is also shown that the BP neural network can improve the prediction accuracy for the position of droplets relative to the nozzle, at a given moment. Under typical working conditions, P(t) is not consistent. As a result, the ejection state is not consistent either. These prediction models may be used for real time monitoring and control of the pneumatic micro-droplet generator.

An explicit expression of a C¹ piecewise variable degree rational interpolation spline is developed, which produces a convex (concave) interpolant to given convex (concave) data directly. The interpolant contains two local shape parameters which serves as local tension factors. Convergence analysis shows that the interpolant has O(h²) or O(h³) approximation order.

In this study, machining problems that can be solved by a numerical controller are considered, and a solution method is proposed. Regarding the data flow of machining process chains, product shape data created by computer-aided design (CAD) are converted into point sequence data by computer-aided manufacturing (CAM) to create a machining program in the machining process chain. Computer numerical control (CNC) faithfully interpolates a dedicated CNC program (ISO code) indicating a tool path and processing conditions, called G code, for machining a workpiece. However, there are no design shape data in the machining process. As the result, accurate measurement and correction with additional processing are required to obtain a high-precision product shape. In this study, as a mechanism that enables information flow belonging to CAD and CAM to be shared without losing it until CNC program execution, the implementation of an integrated CNC system with a shared database is addressed. Information in this database is described according to a predetermined format as data models. The data model that is the basis of information sharing and its practical use are described. Forming characteristic lines on a die were applied for confirmation of the effectiveness of the mechanism using data model. It was confirmed that actual machining realized high machining accuracy compared to the conventional technology.

Toe-in and camber on the front and rear wheels are two important parameters which affect tire abrasion of automobiles, driving and braking stability, front wheel shimmy and so on. The reasonable matching calculation between Toe-in and camber has always been a problem in the design of vehicle four-wheel alignment parameters. The cornering property is one of the key factors influencing the matching accuracy between toe-in and camber and it is a difficulty to establish the matching formula of the two. In order to obtain a more accurate matching relationship，A new formula of matching toe-in and camber based on the existing research results assuming that the tires are rigid, which considers the cornering characteristics of tires, is established to decrease the tire abrasion，front wheel shimmy and increase the driving and braking stability of automobiles. The new formula is verified by testing the front wheel sideslip and tire abrasion of a truck model. The test results show that the matching formula adjusted toe-in and camber is reasonable. From previous studies and the principle of balance between lateral force of camber and cornering force of toe-in, a new calculation method to match toe-in with camber reasonably is proposed.

In this study, we describe a novel mechanical vibration suppression method for high-speed contouring motions. In this method, vibration compensation torque was applied to suppress mechanical vibrations during high-speed contouring motions. The parameters of the compensation signal were determined using commanded acceleration and time for acceleration and deceleration, which were set as numerical control (NC) parameters. We also propose an autonomous compensation-torque-generation algorithm based on the acceleration command from NC. The effectiveness of this method was assessed by measuring and simulating rectangular corner contouring motions in which the compensation torque is applied. The results confirmed that the proposed method can effectively suppress the vibration when the motion direction changes. This method can also be effectively performed at various feed speeds by automatically adapting the torque based on the proposed criteria.

There is always strong impetus to shorten the manufacturing lead-time of mechanical products. Seeking higher efficiency through multi-tasking machine tools has attracted attention for its many advantages in the field of machining. There are a lot of different kinds of multi-tasking machine tool structures that have both turning and milling functions. Therefore, the machining operations are generally complicated, and it takes a great deal of time and labor to generate numerical control (NC) programs. To reduce preparatory time, computer aided process planning (CAPP) systems are needed to automatically determine machining process parameters such as machining sequence, cutting tool, cutting conditions. This study aims to develop a CAPP system for multi-tasking machine tools with two confronting spindles to deal with complicated machining operations. Chucking switch for a workpiece between two confronting turning spindles is introduced to realize 6-face machining of complex target shapes A workpiece shape and target shape are divided into two domains related to the main turning spindle side and sub turning spindle side, respectively. Then, the machining features can be recognized from each domain according to the assumed spindle side. Moreover, parallel machining using plural functions of turning and milling can be achieved by recognizing machining features that are simultaneously machined by the same machining method. The results of case studies confirmed that the developed CAPP system is effective for NC program generation of complicated machining operations on multi-tasking machine tools.

A wedge cutting method with a center-beveled blade is widely used for cutting various laminated sheets such as printed labels, optical adhesive sheets, and multi-functional adhesive films for electronic equipment. In general, the laminated sheet has a pressure-sensitive adhesive (PSA) in the intermediate layer. When a wedge blade indents to a laminated sheet, trouble occasionally occurs because of the blade getting with PSA and PSA flowing out from the cut surfaces. This problem has not been sufficiently clarified. Several reports exist about the cutting behavior of a laminated structure composed of paperboard and monolayer viscoelastic material; however, almost no reports exist on the cutting behavior of laminated sheets with PSA. Therefore, this paper aims to elucidate the effect of a wedge shape on the cutting behavior of a laminated sheet with PSA and polyethylene terephthalate (PET). The cutting characteristics of a 0.1 mm PSA layer sandwiched by upper and lower PET films of 0.1 mm were experimentally and numerically investigated. The cutting load response was measured using indentation depth when the apex angle of the wedge blade was changed. A CCD camera was also installed for investigating the side-view deformation of the laminated sheet. When an apex angle from 16° to 60° was chosen, the cutting force and the bent-up angle of the laminated sheet linearly increased with respect to the apex angle for certain shallow indentation depths. The experimental results showed that the cutting load response and deformed state of the laminated sheet were similar to those of the visco-elastic model based on finite element method (FEM) simulation. In addition, the peak force and the bent-up angle considerably increased with the apex angle, especially when a large apex angle was chosen The fact that the apex angle influenced the cutting characteristics of the laminated sheet during wedge indentation was clarified.

A recently proposed data-driven approach to reliability-based design optimization of structures constructs a sufficient condition that the target reliability is guaranteed with the specified confidence level, without relying on any assumptions on statistical information of random variables. In general, there exists a gap between this sufficient condition and the original confidence-level constraint. This paper presents a simple dimensionality reduction technique that can possibly mitigate this gap. This technique is applied to the compliance constraint with the uncertain external load. Numerical experiments on truss and continuum examples demonstrate that the proposed method can drastically reduce the over-conservativeness of the original method.

Industrial product form design has become consumer-centred. Affective responses related to consumers' affective needs are considered invaluable for product form design and have attracted increasing attention. When designing product forms, designers should thoroughly understand the design knowledge concerning multiple affective responses and design variables. This paper proposes a systematic approach to extraction of design knowledge by using multiobjective optimisation and rough sets. Design analysis is first employed to determine design variables and multiple affective responses. As per the results, a multiobjective optimisation model is constructed that involves optimising the multiple affective responses. An improved version of the strength Pareto evolutionary algorithm (SPEA2) is adopted to solve the multiobjective optimisation model and generate the Pareto optimal solutions. Based on these Pareto optimal solutions, rough sets are employed to extract design knowledge that is common to these Pareto optimal solutions. A car profile design was employed as a case study to illustrate the proposed approach. The results suggest that the proposed approach is time- and cost-efficient and can effectively extract design knowledge that provides suitable insight into product form design.

Surface deformation operations commonly require the local details to be preserved as much as possible. In recent years, the As-Rigid-As-Possible(ARAP) shape deformation has gained popularity. Existing ARAP deformation methods define a local cell at each vertex as its 1-ring neighborhoods, and keep the deformation in each local cell as rigid as possible. Since the local cells of adjacent vertices share a single edge, the consistency between adjacent local rigid transformations maintains relative weak. In this paper, we define a new face-based local cell, which expands the overlapping areas between adjacent local cells, thereby enhancing the consistency of adjacent local rigid transformations. Based on this, we further present a stiffness control surface deformation method. The size of the proposed local cell controls global stiffness of the shape. For each local cell, a local stiffness parameter can be specified by the user or can be learned from a set of deforming models automatically to control the local deformation. Through adjusting the size of the local cell and local stiffness parameter, we can generate physically plausible, material-aware deformation results. Based on this local cell, we further propose a shape interpolation method, which has better performance and extrapolation capabilities. Experimental results demonstrate the effectiveness of our method.

Due to the heterogeneity of advancing face and the top-heavy structure of main machine, hydraulic cylinders of thrust system in shield machine are subjected to the transverse and longitudinal resistance torque varying in a certain interval which would give rise to bias load. Aiming at resisting unbalance load, a kind of thrust system which can regulate all jacks by a layout adjustable mechanism has been proposed in this paper. Considering the workspace, the limited space in the main machine of the machine and the ultimate strength of lining segments, the synthesis dimensional design for the adjustable mechanism has been studied. Under given the working conditions, the force transmission performance for the thrust system with the ability of adjustable layout has been investigated by virtual prototypes using variation coefficient assessment model. Results shown that the adjusted non-uniform thrust system has a better force transmission performance than prior to the uniform thrust system. It also implies that the regulated arrangement thrust system has the strong ability of decomposing external partial loads and prevention of lining segments. Results would provide theoretical foundation and support for the design of the thrust system with an ability of resisting bias load.

The hydraulic driving source plays an important role in the performance of the electro-hydraulic robot. In this paper, the Lumped parameter method is used to establish the pressure-flow characteristic model of the constant pressure variable pump of a 6-DOF electro-hydraulic robot, and attain the influencing factors of the flow pulsation. The simulation model of the electro-hydraulic robot is established, which is used to study the oil property and plunger leakage characteristics of the constant pressure variable pump on the affection of the flow pulsation. The experimental results display that the elastic pulsation is the main form of the output flow pulsation of the constant pressure variable pump, and the pulsation rate will increase with the load quantity of the robot.

In the paper, spatial meshing theory of involute spiroid gear drive with line contact (ISGDWLC), which is a new type of worm drive with large ratio, crossed axes and high load capacity, is presented completely for the further researches of load capacity, wear and efficiency. The methods of modeling and motion simulation are also brought forward on CATIA. Firstly, based on the spatial meshing theory, the theoretical model of ISGDWLC is proposed, including equations of flanks, meshing equation, nonundercutting conditions, conjugate zone, sliding angle and induced normal curvature. Secondly, a set of formulas for the design of ISGDWLC is provided, which has solved the problems such as undercutting, interference and redundant line of contact. In addition, in the light of simultaneous equations method the length of contact is calculated accurately, easily and rapidly. Finally, a numerical example is supplied and its sliding angle, induced normal curvature and length of contact are analyzed utilizing MATLAB. The calculations are done in a second and the analytic solutions are got. The results show that ISGDWLC not only has a simple calculation and stable instantaneous transmission ratio but also has a slight edge in local meshing performances compared to other spiroid gear drive. It has the potential to be widely used. At present, a prototype has been established according to the above work.

Complex eigenvalue analysis has generally been applied to squeal improvement of automotive brake systems in recent years. Discrimination of the occurrence of unstable vibration by modal coupling has become common in brake design. However, the generation mechanism is not fully understood. In particular, the transition of the eigenvalue and the bifurcation phenomenon accompanying the change of the equation of motion are difficult to predict quantitatively. One reason is that a degree of instability can be expressed by real parts of eigenvalues, but the difficulty of the coupling cannot be determined by real parts of eigenvalues. In this report, to obtain a stability index before the coupling, characteristic polynomials are the subject of this research. For the structural instability problem of a two-degree-of-freedom system, which involves a typical friction-induced vibration, the positions of the eigenvalues are geometrically shown on a complex response surface using a real part of the characteristic polynomial. The characteristic polynomial of the two-degree-of-freedom system becomes a complex quartic function; as a result, a saddle-shaped response surface that intersects the complex space appears. Without damping, when the surface and a zero plane of the complex space intersect on an imaginary axis, uncoupled eigenvalues appear. When the surface does not intersect on the imaginary axis, the eigenvalues become complex, and unstable vibration occurs. In a parameter study, a friction coefficient raises the surface monotonously, while mass and stiffness change the eigenvalues in the same way as curve veering, and damping breaks the symmetry of the surface and shifts the surface to the stable side. The vertex in the imaginary axis cross section of the surface is a point at which the eigenvalues reach the coupling. This point serves as a guideline for the stability before the coupling. Consequently, it is useful for evaluating the transition of the eigenvalues.

This research has been conducted to develop computer aided manufacturing software, which can generate NC programs for a five-axis directed energy deposition (DED) type additive manufacturing system with following three focuses: 1. How to maintain consistent formation of a melt pool on the surface of the workpiece. 2. How to generate three-dimensional deposition path efficiently when a 3D part model is given. 3. How to control process parameters during additive operation. For focus 1, the work orientation has been controlled such that the surface to be deposited can remain perpendicular to the nozzle which is fixed to gravity direction and minimize distortion of the laser spot and powder distortion on the workpiece surface. For focus 2, a unique path generation method has been proposed based on the reverse play of a subtractive machining path, which removes the entire part to the null. For focus 3, preoperative process parameters control has been introduced to achieve the specified volumetric deposition rates along the additive tool path, which is equated with the material removal rates along the subtractive machining tool path. With methods mentioned above, the dedicated CAM system, CAMAM, has been prototyped and its feasibility has been verified experimentally by applying the NC program generation strategies to deposit several parts.

This research aims to develop a new ride comfort simulation technology for a three-axle heavy vehicle. To consider the elasticity of the frame, the finite element method (FEM) is used to analyze the free mode of the frame, and the elastic information of the frame is obtained. Based on the theory of rigid-elastic synthesis, a 17-degree-of-freedom (DOF) spatial rigid-elastic model of a three-axle heavy vehicle is established. The pseudo-excitation method (PEM) is adopted to improve the efficiency of the solution, thereby solving this problem. The pseudo road excitation is constructed, the pseudo responses of the vibration system and the response variables are derived, and the power spectral densities (PSDs) and the root mean square (RMS) values of the responses are deduced. Twenty response variables are used, including accelerations, suspension dynamic deflections, and relative dynamic loads of wheels, whose PSDs and RMS variables are used as evaluation indexes. Finally, a comparative study of ride comfort simulation is conducted. A comparison of the simulation results of the rigid-elastic and rigid models indicates that the elasticity of the frame considerably influences the ride comfort of the heavy vehicle and hence cannot be ignored in the study of this issue. Meanwhile, a comparison of the results of PEM and the Fourier method for the spatial rigid-elastic model of the three-axle heavy vehicle shows that PEM is accurate yet simpler and more efficient than the Fourier method. Therefore, the innovative simulation technology proposed in this work is practical and efficient and can reflect the essence of the problem.

In order to obtain locally conjugated tooth surface contact, a tooth surface mismatch modification method is proposed based on the fully conjugated characteristics of cycloidal bevel gear. Firstly, according to the principle of fully conjugated, the mathematical model for calculating the cutting parameters of cycloidal bevel gear is established, and the calculating method of the cutting parameters of the fully conjugated tooth surface is deduced. Secondly, the double crowned tooth surface modification method is studied, and the tooth length direction modification is realized by modifying the radius of the cutter blade edge, and the tooth profile direction modification is realized by modifying the shape of cutter blade edge, so that the fully conjugated tooth surfaces meshing with each other are mismatched in the directions of tooth length and tooth profile. On this basis, the mismatch coefficients of tooth surface are calculated by means of polynomial expression of second order. Five coefficients in the mismatch relationship of tooth surface are corrected to modify the tooth surface of pinion again, and the original cutting parameters of pinion are corrected. And then, the required mismatch relationship of tooth surface is obtained. Finally, a pair of cycloidal bevel gear is analyzed in the process of tooth surface mismatch modification. The results of gear cutting experiments are consistent with the simulation results, which verify the effectiveness and feasibility of the proposed tooth surface mismatch modification method.

Grinding chip thickness is an important parameter to reflect the grinding efficiency and investigate the grinding mechanism. Modeling of the chip thickness is generally based on a certain stochastic distribution model, like Uniform, Gaussian or Rayleigh distribution. This paper is devoted to establish the real grinding chip thickness distribution model for brittle materials based on the material removal mode: coexistence of ductile and brittle removal mode. A grid calculation method will provide a quantitative data of ductile removal surface to validate the chip thickness model. The results show that the grinding chip thickness for Silicon Carbide ceramics is more close to the Rayleigh model with an average error of 3.25% compared with 11.74% of Gaussian model. Finally, grinding experiments were conducted to reveal the Rayleigh model-based grinding temperature characteristics, surface roughness and topography. It was found that ductile-oriented ground surface with a lower surface roughness value was increased with the enhancement of the ductile surface percentage and a substantial suppression of surface crack and damage generation.

A variable fidelity concept is introduced in a re-parameterization approach based on the proper orthogonal decomposition (POD) to efficiently solve multi-objective aerodynamic shape optimization problems. The re-parameterization approach enables to extract dominant shape deformation modes from a database of good designs and to reduce the number of design variables. The present variable fidelity approach is proposed by utilizing low-fidelity functional evaluations to select the good designs. The proposed approach is investigated in two multi-objective aerodynamic shape optimization problems of 2D airfoil in which the combinations of viscous/inviscid simulations or fine/coarse grid simulations are treated as the high/low-fidelity evaluation methods. It can be confirmed that dominant POD modes obtained from low-fidelity evaluations are qualitatively equivalent with that obtained from high-fidelity evaluations. Non-dominated solutions obtained from a conventional optimization approach can be reproduced with smaller numbers of design variables using the dominant POD modes. The computational costs to solve the multi-objective aerodynamic shape optimization problems can be dramatically reduced by introducing the variable fidelity concept.

Cutting forces are often used to optimize cutting parameters and analyze cutting characteristics of the tool. Accurate prediction of cutting forces is critical to understand deeply of the cutting process, especially for helical milling of the difficult-to-cut materials. Generally, the cutting force coefficients are not affected by the cutting parameters in the end milling process, but due to the special cutting mechanism of helical milling, the change of the cutting force coefficients must be carefully studied. However, the identification of cutting force coefficients is very important to simulate cutting forces accurately, and the relationship between cutting force coefficient and cutting parameters needs to be carefully considered. To analyze the change of cutting forces, this paper respectively proposes linear and nonlinear cutting force models applied for the helical milling process, then according to the helical milling experiments, cutting coefficients are identified using an inverse method through instantaneous force in the linear model, at the same time, the coefficients are identified by similar average force method in the nonlinear model, simulated three-direction cutting forces under two different situations are compared to the experimental results. The relationship between cutting force coefficients and cutting parameters is analyzed in detail, the linear and nonlinear models as well as the fitting relations of different cutting force coefficients are compared. The aim of this paper is to study the influence of cutting parameters on the cutting coefficients, thus create a model to predict reliably the cutting force with different cutting parameters.