International Journal of Materials and Product Technology (6 papers in press)

Regular Issues

• A finite element model of fracture toughness of ultra-high performance concrete  
  by Zhi-yong He, Ya-feng Zhang, Tian-you Chen 
  Abstract: UHPC is the most promising building material. It is of great significance to establish a finite element model that is consistent with the actual situation for the study of the mechanical properties of UHPC. The paper presents a numerical method for modelling the fracture toughness of UHPC. The finite element model adopts separated modelling, considering UHPC as a two-phase material, and establishes a concrete matrix model and a steel-fibre model respectively. The concrete matrix adopts the concrete damaged plasticity (CDP) model. A large number of disjoint and randomly distributed cylinders are generated in Abaqus through Python to simulate steel fibres and are embedded in the concrete matrix. The bond-slip relationship between steel fibres and concrete is indirectly simulated through the tensile stress-strain relationship of steel fibres. The finite element model is used to simulate the uniaxial tensile experiment and the three-point bending experiment of UHPC. The established finite element model is of higher accuracy than the line-element steel-fibre model used in previous studies, and is more consistent with experimental data, which verifies the effectiveness of the numerical method.
  Keywords: ultra-high performance concrete; UHPC; concrete damaged plastic; CDP; finite element model; fracture toughness; Abaqus.
  
  

Special Issue on: Computational Materials Modelling, Analysis and Applications Part 2

• Fatigue life prediction method of complex mechanical structure based on EMD  
  by Mengqi Xie, Ningchao Zhang, Peng Wang 
  Abstract: In order to improve the accuracy of prediction results, a fatigue life prediction method of complex mechanical structures based on EMD is studied. Firstly, the complex mechanical structure signal is decomposed into several eigenmode functions by EMD decomposition method. Then, the orthogonal coefficient is introduced to improve the EMD decomposition method, and the decomposition results of vibration signals of complex mechanical structures are output. Finally, the results of vibration signal decomposition are used as the input of support vector regression machine, and the fatigue life prediction model of complex mechanical structure is constructed, and the fatigue life prediction results are output. The experimental results show that this method can effectively denoise the signal, and the accuracy of the prediction results is high, which shows that the prediction results are reliable.
  Keywords: EMD; complex mechanical structure; fatigue life; forecasting method; intrinsic modal function; orthogonal coefficient.
  
  
• A vibration fault diagnosis method for vehicle bearings based on acoustic sensing technology  
  by Jiajia Li, Zhoubohan Liu, Gengming Xie 
  Abstract: To improve the diagnostic sensitivity of vibration faults of removed bearings, the paper proposes a diagnostic method based on acoustic sensing technology. Firstly, a capacitive sound pressure sensor is used to collect vibration signals of vehicle bearings and perform denoising processing to calculate the modal component change rate of bearing vibration displacement. Then, based on the vibration measurement characteristics, the types of vehicle bearing vibration faults are divided. Finally, extract the features of the fault vibration signal, calculate the frequency deviation of the fault centre, and then diagnose the area where the fault signal is located based on the fuzzy membership degree between the fault signal and the normal signal. Experiment shows that the signal-to-noise ratio of the fault vibration signal obtained by this method is maintained at around 95 dB, and the diagnostic sensitivity is between 0.92 and 0.98, indicating that the method has achieved the design goal.
  Keywords: vehicles; bearing vibration; vibration fault; capacitive sound pressure sensor; wavelet transform; frequency deviation of fault centre; fault diagnosis.
  
  
• A method for selecting the grasping path of a multi degree of freedom robot arm based on laser ranging technology  
  by Hui Yan, Yunxin Long, Huangbin Guo, Ping Yu, Duo Long 
  Abstract: In view of the shortcomings of large grasping displacement, poor stability and large energy loss of each axis, the method of grasping path selection is proposed based on laser ranging technology. First, establish the position coordinate system of the grasping arm; second, realise the target calibration of the grasping arm through homogeneous transformation; again, construct the dynamic model of the grasping process; finally, the grasping path selection of the grasping arm is realised through the stochastic road map algorithm (PRM). It is proved that the grasping displacement of the robotic arm can be kept below 1.5 cm, and the energy consumption of each axis of the robotic arm is 14~24 kW, and the energy consumption is low, and has good application performance.
  Keywords: laser ranging; multi degree of freedom robotic arm; coordinate system; dynamic model; grab path.
  
  
• Strength analysis of vehicle body skeleton structure based on finite element model  
  by Hui Wang, Cheng Yang 
  Abstract: In order to overcome the problems of low identification rate and accuracy, as well as long analysis time in traditional methods of automobile body structure strength analysis, a strength analysis method of vehicle body skeleton structure based on finite element model is proposed. Determine the vehicle coordinate system and build a vehicle dynamics model, and use the Kalman filtering method to identify the structural parameters of the vehicle body skeleton. Build a finite element model of the automotive body skeleton structure through discretisation and element analysis. Obtain the strength analysis results of the car body skeleton structure by calculating the yield limit of the car body skeleton structure. Experimental results show that the average identification rate of the proposed method for automobile body structure parameters is 97.74%, the maximum accuracy of the strength analysis of the automobile body structure is 97.3%, and the average analysis time is 65.28 ms.
  Keywords: finite element model; vehicle body; skeleton structure strength; kinematic model of the vehicle; Kalman filter; yield limit.
  
  
• Non-destructive testing method for building material defects based on image processing technology  
  by Yufeng Chi, Ligang Qiao, Shuting Hu, Peng Yu, Haoxiang Tang 
  Abstract: In order to improve the detection accuracy of building material defects and shorten the detection time, a non-destructive testing method for building material defects based on image processing technology is proposed. Firstly, an array CCD camera is used to capture images of building defect material. Secondly, in order to improve the quality of building material images, image processing techniques are adopted, including greyscale processing, edge enhancement, and smooth filtering. Finally, the triangulation method is used to segment the defect areas and background areas in the building material image, completing non-destructive testing of building material defects. The experimental results show that the method proposed in this paper can improve the quality of building material images, improve detection accuracy, and shorten detection time.
  Keywords: image processing technology; defects in building material; non destructive testing; greyscale processing; triangulation method.