Residual stress detection of welded parts based on excitation vibration response

With the rapid development of the equipment industry, people pay more attention to the stress research of materials. However, there is no more suitable and effective method to detect the variation of residual stress. To find an efficient and useful method to analyze the residual stress of the welded parts, this article selects the Q235 component as the research object and produces a detection robot with the core of processing vibration signal and extracting signal data. In combination with the vibration signal extracted by the robot, we study the influence law of the residual stress of the material through numerical simulation and experimental verification. The detection of residual stress is related to the change in the number of taps of the robot and the increase or decrease in the number of taps of the robot. We used the vibration signal extracted by the robot and analyzed the orthogonal parameters of the high-frequency induction welding process parameters to obtain a set of the most unique process parameters: The tapping angle was 7° and the tapping frequency was 300 Hz. We also set up the robot to extract and analyze the vibration signal using four different hammerheads. The results show that the sub-resonance analysis results as the standard, the deviation of the steel head and the aluminum head hammer is about ±10, the result is more accurate, and the frequency of the nylon and plastic hammer is lower, because it is softer. When the hammer is struck, the contact time of the hammerhead with the workpiece is lengthened, so that a lower frequency can be excited.

Formulation of the Phasors of Apparent Harmonic Power: Application to Non-Sinusoidal Three-Phase Power Systems

In this work, the expression of the phasor of apparent power of harmonic distortion is formulated in the time domain. Applying this phasor along with the phasor of apparent unbalance power allows us to obtain a new set of phasors that include all of the inefficient power components appearing in the transfer of energy in non-linear and unbalanced systems. In this manner, a new model of inefficient power in electrical systems is developed. For each voltage harmonic of order ‘m’ and current harmonic of order ‘n’, a phasor of harmonic apparent power is obtained. Accuracy in the determination of the total apparent power of a system depends on the number of harmonics considered. Each phasor of apparent harmonic power is formed from six mutually orthogonal parameters or components that are calculated from the harmonic voltages at the nodes of the network and the circulating harmonic currents. To demonstrate the validity of the proposed formulation, a four-wire non-linear system formed by two nodes is assessed.

Optimal Desigh of Self-Sealing Low Friction and Non-Leakage Plunger Pump

A new type of wear-resistant hydraulic feedback self-sealing plunger pump is proposed. finite element analysis and optimal design of orthogonal parameters are applied to determine the structural parameters. The pump overcomes the conventional piston friction, low efficiency, short life. Laboratory tests showed that the pump free down stroke, full returns, leakage reduction 1,000 times than the standard API. Field experiments indicate that pump efficiency attain to 60-80%, achieved a good energy saving effect of improving the pump efficiency.

RECOGNITION OF 3D THIN-PLATE OBJECTS USING ORTHOGONAL AR MODEL

A three-dimensional (3D) autoregressive model is introduced for modeling, invariant feature extraction and recognition of arbitrary 3D thin-plate objects. An orthogonal estimation algorithm is derived for the estimation of the coefficient matrices associated with the object boundary and error reduction ratio is used to determine the sufficient order of the model to describe the boundary. It is shown that the eigenvalues, traceand the determinant of the orthogonal coefficient matrices are invariant to rotation around the origin, to the choice of starting point in tracing the boundary and to scale and translation, and classification based on orthogonal parameters is shown to be less susceptible to incorrect model order specification.