Li Quan Wang

Atomics simulation of cutting velocity dependency in AFM-based nanomachining process

Three-dimensional molecular dynamics simulations are performed to investigate the AFM-based nanometric cutting process of single crystal copper. The effects of cutting velocities (180, 360, and720 m/s) on the cutting force, the ratio of the thrust force and cutting force and subsurface layers. The results show that the dislocations nucleate beneath the tool, and propagate along the [-11-1] direction in the (111) plane. The effects of the nanocutting action from the tool on the subsurface damaged layers decrease gradually as the distance from the tool tip increases. With the increasing cutting speed, the cutting forces increase accordingly. However, the ratio of the the ratio the thrust force and cutting force decrease as the cutting speeds increase. With the proceeding of the cutting process, that tends to the same on the whole.

Dynamic Humanoid Gait Simulation of Biped Robot Based on ADAMS

During the design of biped robot HEUBR_1, a new structure of tandem and parallel connection is used in lower-limbs, adding toe-joints to feet. In order to make sure the rationality of humanoid structure design and feasibility of the humanoid gait planning, we built the simulating model of biped robot HEUBR_1 by using software ADAMS. The simulating model of biped robot HEUBR_1 walked stably with toe-joints in fictitious surrounding, which used the motion data exported by humanoid gait planning. During humanoid gait simulation, the biped robot kinematic and dynamical characteristics were achieved. Simulation indicates that the structure of tandem and parallel connection is rational and the method of humanoid gait planning is feasible. Humanoid walking with toe-joints has the characteristic: balanced motion, lower energy and small impact on feet. Simulated data of steady walking will be used as reference for biped robot HEUBR_1 walking experiments.

Design of a Crab-Like Octopod Robot

A crab-like octopod robot is introduced in this paper. The body structure of the robot is simuliar with a real crab. Each leg has three jionts which are driven by servomotors. The control system is a distributed hierarchical system with a top layer as gait generator and a bottom layer as servomotor controller. The bottom layer has enght individual control units every of which can control three servomotors using PID control method. The sensor systerm is composed of force sensors mounted at the end of the leg and a inclinometer provides pitch and roll angles of the body.

Dynamic Response of Hammer Impacting Pile under Gravity Field

Pile hammer impact system is composed of hammer, pile cap and pile. Gravity field will produce uneven stress in the pile which is placed on a fixed rigid plane, and gravitational potential energy will increase the impact energy which is inputted to the pile during the impact process. These will influence dynamic response of collision process between pile hammer and pile. In this paper, a gravity field factor was added in the Simth difference equations which are based on One-dimensional Wave Equation. The numerical model of pile hammer impact system was established. A program was written to implement the numerical model. Simulation results indicated that the duration of collision, the peak and stable value of impact force and the effective impact energy would be affected by the gravity field.

Design on a Kind of Tension Test Sensor of Saw Wire

Using diamond saw wire can incise the seabed oil compound pipes, and its state being incised can be monitored by measuring the tension of diamond saw wire, so, it makes the cutting and advancing velocities under the condition of harmony. At first the tension of saw wire was analyzed at its working condition, the mechanism of the tension sensor was designed by the method of composition of forces, and put forward the measuring method about tension of saw wire based on up-down single chip communications. Next, the tension sensor was designed and its detection principle was introduced. Its calibration and accuracy were carried out. In the end, the test of examining tension underwater was done and validated its feasibility and reliability. it shows that the value of tension changes between 40N and 60N basically when the cutting velocity is in harmony with the advancing velocity.

Groove Optimization and Finite Element Analysis for Different Groove Milling Insert

Based on the experiments on milling the 45 steel with several types of different grooves milling inserts, this article has groove optimization and finite element analysis for different groove milling inserts. With the milling force testing system and orthogonal experimental design method, we have experiments with five types of different groove milling inserts for machining the 45 steel and compare their cutting capability, and the different grooves milling inserts are optimized. Based on the experiments, we have stress field analysis for different grooves milling inserts with finite element analysis method. The finite element analysis results are consistent with the experiment results well. All these studies provide the theoretic and experimental bases for groove development and groove optimization technology.

Research on the Construction Strength and Pressurize Capability of Two-Joint Mating System of Underwater Vehicle

With the development and researching more on the ocean, underwater mating technique has been widely used such as ocean workstation, aid submarine lifesaving and military affairs field. In this paper, in order to increase capacity of adapting platform obliquity and adopting rotational skirt scheme, two-joint mating system of underwater vehicle was designed including three-dimension assembly design and control system. It is indicated that the system can meet working space of underwater vehicle passageway and there is not interference phenomenon by assembly design. The finite element of system shell and pressurize of the joint was established. The computing result and pressing test is accordant, thus it is testified that the shell material can meet strength need and joint pressurize is reliable.

High-Accuracy Shape Construction of Porcelain and Exhibiting on Web

The key of 3D measurement technology based on coded structured light for high-accuracy reconstruction of porcelain exhibited on Web, is to ensure measurement accuracy and anti-interference capability on high reflectance surface. So an edge Gray code method for structured light system and related technologies are proposed under interference by high reflectance ratio and color of measured surface. Firstly, encoding and decoding principles by Gray code stripe edge reduce theoretical quantization error and decoding error against traditional Gray code, so measurement accuracy is improved. Secondly, stripe edge sub-pixel location method based on grey curve intersecting points is designed to reduce edge location error caused by diffusion from white stripe to black stripe. Measurement system was established according to mathematic model. Experimental results show that error of measured high reflectance unicolor standard plane is 0.60.8mm, and reconstructed porcelain shape has same visual effect as the real one. Finally, based on Java 3D, interactively exhibiting on Web was explored.

Study on Object Function of Milling Insert Impact Disrepair Based on Stress Field Analysis

This article takes the waved-edge milling insert (the rake face is curve plane) developed by Harbin University of Science and Technology as an example, as the goal of minimal impact disrepair, the optimization object function of the milling insert grooves is studied. Based on the force density function of the 3D complex groove milling insert, we have the finite element analysis on the stress fields of different cutting parameters, and have fuzzy synthetical judgement on the stress fields with fuzzy mathematic theory. We build the object function relation between the fuzzy synthetical judgement results and cutting parameters of the impact disrepair, so to have groove design optimization. All these studies provide the theoretic basis for the groove exploitation and the cutter disrepair which is the key problem in the automatization production and groove optimization.

Mechanics Analysis on Leveling Tool of Offshore Jacket Platform

The paper aimed to leveling operation of offshore jacket platform, studied mechanics principle of the leveling tool. When the clamp blocks inserted into the pile wall in leveling operation, the pile’s surface presented some indentations of elastic-plastic deformation, which can increase the cross-lifting force but the clamp is susceptible to be damaged certainly. So, special clamping block was designed including its material and mechanical structure, and force analysis of the pile under the action of the clamping blocks was finished, and dynamics simulation of contact process between the clamping block and the pile was finished too. An experimental prototype was developed to verify the clamping principle. Experimental results show that the clamping principle is correct and the leveling tool can meet actual needs.