Baiqiao Chen | Universidade de Lisboa (original) (raw)

Papers by Baiqiao Chen

Research paper thumbnail of Displacement Measurement of Box Girder Based on Photogrammetry

Research paper thumbnail of Automatic Approach for Measuring Deformations in Complex Structures Using Photogrammetry Technique

Research paper thumbnail of Comparison between different heat sources types in thin-plate welding simulation

IMAM 2013, 2013

ABSTRACT The effect of three different kinds of heat input on the behaviour of finite element mod... more ABSTRACT The effect of three different kinds of heat input on the behaviour of finite element models of three dimensional elasto-plastic analysis of the response of plates subjected to welding are studied. The models used are Gaussian, semi ellipsoidal and double ellipsoidal, which are applied to stainless steel thin plates. Temperature-dependent material properties are adopted as they are important to consider in transient thermo-mechanical analysis. Temperature distribution, residual stresses and distortions are cal- culated in each case and numerical results are verified against published experimental measurements. It is shown that all of the heat sources have similar results of temperature distribution but the semi ellipsoidal and double ellipsoidal sources have more accurate results in structural response. It is found that consider- ing the thickness direction in applying heat input is important even in thin plates. Accordingly to welding processes such as GMAW or laser welding, the semi ellipsoidal and double ellipsoidal models represent well experimental results and real conditions.

Research paper thumbnail of Numerical analysis of the effects of weld parameters on distortions and residual stresses in butt welded steel plates

The objective of this work is to develop 3D models and techniques for predicting the tem-perature... more The objective of this work is to develop 3D models and techniques for predicting the tem-perature field, distortions and residual stresses induced by a butt welding process. Finite element model of a plate subjected to double ellipsoidal moving heat source has been developed to simulate the welding process. The obtained transient temperature distributions have been applied as thermal loads in mechanical analyses to predict the structural responses. Temperature distribution, residual distortion, and shrink-ages of the plate have been calculated and discussed in detail after validating the proposed numerical approach. The longitudinal stresses in different sections have been discussed and verified with theoretical prediction. As the continuously work of the previous study on the effects of weld parameters on the thermal response, their effects on the structural response of butt-welded plates are included as well.

Research paper thumbnail of Thermo-mechanical analysis of the effects of weld parameters in ship plates during welding process

The objective of this work is to develop models and techniques for predicting the temperature fie... more The objective of this work is to develop models and techniques for predicting the temperature field and distortions in-duced in ship plates by the welding process. Finite Element models representative of real ship structures and compo-nents have been developed to simulate the transient thermal analysis with moving heat model. Results have been compared to numerical and experimental results obtained by other researchers. The time variant temperature distribu-tions obtained have been applied as thermal loads in mechanical analyses to predict the plate distortions. The study of the effects of different parameters on the welding response, including the torch speeds, heat inputs, thicknesses of plates has also been included.

Research paper thumbnail of Mechanical properties assessment of specimen subjected to random non-uniform general corrosion and tensile load

Maritime Engineering and Technology, 2012

Research paper thumbnail of Measurement of Weld-Induced Deformations in Three-Dimensional Structures Based on Photogrammetry Technique

This paper presents an approach for measuring weld-induced initial distortions in plated structur... more This paper presents an approach for measuring weld-induced initial distortions in plated structures, allowing also for the possibility for transferring that information directly to finite element models. Photogrammetry, which employs a three-dimensional measurement technique and central projection imaging as a fundamental mathematical model, has been used to generate the displacement field from sets of digital images of box girders. Three-dimensional deformation models of box girders were obtained before and after a buckling collapse test. A comparison between the photogrammetric result and Smith's initial imperfection classifications has been performed. A new equation to predict the initial imperfections of very-thin-walled structures has been developed. It is demonstrated that the output of the photogrammetry analysis can be used as a direct input to a finite element model of the deformed structure. The procedure was validated against direct measurements of the deflections, and statistical analyses of the error between measurements and photogrammetric evaluations are presented.

Research paper thumbnail of Numerical investigations to study the effect of weld parameters on the temperature-time history in steel plates

Numerical investigations are carried out to study the effect of weld parameters on the temperatur... more Numerical investigations are carried out to study the effect of weld parameters on the temperature-time history in a butt-joint weld steel plate. A mathematical model of transient thermal process in welding is established to simulate the transient thermal analysis with moving heat model (Gaussian function) by using finite element method. Results are compared to numerical and experimental results obtained from a previous study. Parametric studies based on numerical results are carried out for different weld parameters including welding speed, plate thickness, heat input, heat type and finite element mesh.

Research paper thumbnail of Experimental numerical and analytical analysis of the penetration of a scaled double-hull tanker side structure

Research paper thumbnail of Design equation for the effect of ovality on the collapse strength of sandwich pipes

Research paper thumbnail of Effect of non-symmetrical corrosion imperfection on the collapse pressure of subsea pipelines

Research paper thumbnail of Dynamic structural response of perforated plates subjected to water impact load

Research paper thumbnail of Deformation measurements in welded plates based on close-range photogrammetry

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Research paper thumbnail of Deformation measurements in welded plates based on close-range photogrammetry

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Research paper thumbnail of Measurement of Weld-Induced Deformations in Three-Dimensional Structures Based on Photogrammetry Technique

Research paper thumbnail of Automatic Approach for Measuring Deformations in Complex Structures Using Photogrammetry Technique

This work presents an automatic approach for measuring deformations in complex structures and tra... more This work presents an automatic approach for measuring deformations in complex structures and transferring that information directly to a finite element model for further structural analysis. Photogrammetry is used as a three-dimensional measurement technique to identify the displacement field from sets of digital images.

Research paper thumbnail of Displacement Measurement of the Box Girder Based on Photogrammetry

The objective of this work is to generate a threedimensional model of the initial and post test d... more The objective of this work is to generate a threedimensional model of the initial and post test displacement measurements of a box girder. Photogrammetry, which employs a three-dimensional measurement technique and central projection imaging as a fundamental mathematical model, is used to generate the displacement field, from a set of digital photos. A three dimensional displacement model of a box girder before and after an ultimate strength test is performed using appropriate software. The results achieved are very successful as have been proved and can be used as input data to a finite element analysis of the ultimate strength of the box girder subjected to bending moment.

Research paper thumbnail of Numerical analysis of the effects of weld parameters on distortions and residual stresses in butt welded steel plates

The objective of this work is to develop 3D models and techniques for predicting the temperature ... more The objective of this work is to develop 3D models and techniques for predicting the temperature field, distortions and residual stresses induced by a butt welding process. Finite element model of a plate subjected to double ellipsoidal moving heat source has been developed to simulate the welding process. The obtained transient temperature distributions have been applied as thermal loads in mechanical analyses to predict the structural responses. Temperature distribution, residual distortion, and shrinkages of the plate have been calculated and discussed in detail after validating the proposed numerical approach. The longitudinal stresses in different sections have been discussed and verified with theoretical prediction. As the continuously work of the previous study on the effects of weld parameters on the thermal response, their effects on the structural response of butt-welded plates are included as well.

Research paper thumbnail of Mechanical properties assessment of specimens subjected to random non-uniform general corrosion and tensile load

The objective of this work is to analyze the strength and deformability of steel specimens subjec... more The objective of this work is to analyze the strength and deformability of steel specimens subjected to random non-uniform general corrosion and tensile load. The real shape of corrosion surface has been generated by a probabilistic model of corrosion deterioration. Non-linear, large deformation and threedimensional finite element analyses have been employed to analyze the mechanical properties of deteriorated specimens. The strength of corroded specimens is estimated as a function of the average corrosion depth and the minimum cross sectional area. The deformability and energy absorption of the corroded plates are estimated as a function of the surface roughness represented by the difference of averaged plate thickness and that at the section of minimum cross sectional area.

Research paper thumbnail of THERMO-MECHANICAL ANALYSIS OF THE EFFECTS OF WELD PARAMETERS IN SHIP PLATES DURING WELDING PROCESS

The objective of this work is to develop models and techniques for predicting the temperature fie... more The objective of this work is to develop models and techniques for predicting the temperature field and distortions induced in ship plates by the welding process. Finite Element models representative of real ship structures and components have been developed to simulate the transient thermal analysis with moving heat source model. Results have been compared to numerical and experimental results obtained by other researchers. The time variant temperature distributions obtained have been applied as thermal loads in mechanical analyses to predict the plate distortions. The study of the effects of different parameters on the welding response, including the torch speeds, heat inputs, thicknesses of plates has also been included. NOMENCLATURE ) r ( q Heat flux max q Maximum heat flux r Distance from heat source center Q Heat input R Radius of heating spot 1.

Research paper thumbnail of Displacement Measurement of Box Girder Based on Photogrammetry

Research paper thumbnail of Automatic Approach for Measuring Deformations in Complex Structures Using Photogrammetry Technique

Research paper thumbnail of Comparison between different heat sources types in thin-plate welding simulation

IMAM 2013, 2013

ABSTRACT The effect of three different kinds of heat input on the behaviour of finite element mod... more ABSTRACT The effect of three different kinds of heat input on the behaviour of finite element models of three dimensional elasto-plastic analysis of the response of plates subjected to welding are studied. The models used are Gaussian, semi ellipsoidal and double ellipsoidal, which are applied to stainless steel thin plates. Temperature-dependent material properties are adopted as they are important to consider in transient thermo-mechanical analysis. Temperature distribution, residual stresses and distortions are cal- culated in each case and numerical results are verified against published experimental measurements. It is shown that all of the heat sources have similar results of temperature distribution but the semi ellipsoidal and double ellipsoidal sources have more accurate results in structural response. It is found that consider- ing the thickness direction in applying heat input is important even in thin plates. Accordingly to welding processes such as GMAW or laser welding, the semi ellipsoidal and double ellipsoidal models represent well experimental results and real conditions.

Research paper thumbnail of Numerical analysis of the effects of weld parameters on distortions and residual stresses in butt welded steel plates

The objective of this work is to develop 3D models and techniques for predicting the tem-perature... more The objective of this work is to develop 3D models and techniques for predicting the tem-perature field, distortions and residual stresses induced by a butt welding process. Finite element model of a plate subjected to double ellipsoidal moving heat source has been developed to simulate the welding process. The obtained transient temperature distributions have been applied as thermal loads in mechanical analyses to predict the structural responses. Temperature distribution, residual distortion, and shrink-ages of the plate have been calculated and discussed in detail after validating the proposed numerical approach. The longitudinal stresses in different sections have been discussed and verified with theoretical prediction. As the continuously work of the previous study on the effects of weld parameters on the thermal response, their effects on the structural response of butt-welded plates are included as well.

Research paper thumbnail of Thermo-mechanical analysis of the effects of weld parameters in ship plates during welding process

The objective of this work is to develop models and techniques for predicting the temperature fie... more The objective of this work is to develop models and techniques for predicting the temperature field and distortions in-duced in ship plates by the welding process. Finite Element models representative of real ship structures and compo-nents have been developed to simulate the transient thermal analysis with moving heat model. Results have been compared to numerical and experimental results obtained by other researchers. The time variant temperature distribu-tions obtained have been applied as thermal loads in mechanical analyses to predict the plate distortions. The study of the effects of different parameters on the welding response, including the torch speeds, heat inputs, thicknesses of plates has also been included.

Research paper thumbnail of Mechanical properties assessment of specimen subjected to random non-uniform general corrosion and tensile load

Maritime Engineering and Technology, 2012

Research paper thumbnail of Measurement of Weld-Induced Deformations in Three-Dimensional Structures Based on Photogrammetry Technique

This paper presents an approach for measuring weld-induced initial distortions in plated structur... more This paper presents an approach for measuring weld-induced initial distortions in plated structures, allowing also for the possibility for transferring that information directly to finite element models. Photogrammetry, which employs a three-dimensional measurement technique and central projection imaging as a fundamental mathematical model, has been used to generate the displacement field from sets of digital images of box girders. Three-dimensional deformation models of box girders were obtained before and after a buckling collapse test. A comparison between the photogrammetric result and Smith's initial imperfection classifications has been performed. A new equation to predict the initial imperfections of very-thin-walled structures has been developed. It is demonstrated that the output of the photogrammetry analysis can be used as a direct input to a finite element model of the deformed structure. The procedure was validated against direct measurements of the deflections, and statistical analyses of the error between measurements and photogrammetric evaluations are presented.

Research paper thumbnail of Numerical investigations to study the effect of weld parameters on the temperature-time history in steel plates

Numerical investigations are carried out to study the effect of weld parameters on the temperatur... more Numerical investigations are carried out to study the effect of weld parameters on the temperature-time history in a butt-joint weld steel plate. A mathematical model of transient thermal process in welding is established to simulate the transient thermal analysis with moving heat model (Gaussian function) by using finite element method. Results are compared to numerical and experimental results obtained from a previous study. Parametric studies based on numerical results are carried out for different weld parameters including welding speed, plate thickness, heat input, heat type and finite element mesh.

Research paper thumbnail of Experimental numerical and analytical analysis of the penetration of a scaled double-hull tanker side structure

Research paper thumbnail of Design equation for the effect of ovality on the collapse strength of sandwich pipes

Research paper thumbnail of Effect of non-symmetrical corrosion imperfection on the collapse pressure of subsea pipelines

Research paper thumbnail of Dynamic structural response of perforated plates subjected to water impact load

Research paper thumbnail of Deformation measurements in welded plates based on close-range photogrammetry

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Research paper thumbnail of Deformation measurements in welded plates based on close-range photogrammetry

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Research paper thumbnail of Measurement of Weld-Induced Deformations in Three-Dimensional Structures Based on Photogrammetry Technique

Research paper thumbnail of Automatic Approach for Measuring Deformations in Complex Structures Using Photogrammetry Technique

This work presents an automatic approach for measuring deformations in complex structures and tra... more This work presents an automatic approach for measuring deformations in complex structures and transferring that information directly to a finite element model for further structural analysis. Photogrammetry is used as a three-dimensional measurement technique to identify the displacement field from sets of digital images.

Research paper thumbnail of Displacement Measurement of the Box Girder Based on Photogrammetry

The objective of this work is to generate a threedimensional model of the initial and post test d... more The objective of this work is to generate a threedimensional model of the initial and post test displacement measurements of a box girder. Photogrammetry, which employs a three-dimensional measurement technique and central projection imaging as a fundamental mathematical model, is used to generate the displacement field, from a set of digital photos. A three dimensional displacement model of a box girder before and after an ultimate strength test is performed using appropriate software. The results achieved are very successful as have been proved and can be used as input data to a finite element analysis of the ultimate strength of the box girder subjected to bending moment.

Research paper thumbnail of Numerical analysis of the effects of weld parameters on distortions and residual stresses in butt welded steel plates

The objective of this work is to develop 3D models and techniques for predicting the temperature ... more The objective of this work is to develop 3D models and techniques for predicting the temperature field, distortions and residual stresses induced by a butt welding process. Finite element model of a plate subjected to double ellipsoidal moving heat source has been developed to simulate the welding process. The obtained transient temperature distributions have been applied as thermal loads in mechanical analyses to predict the structural responses. Temperature distribution, residual distortion, and shrinkages of the plate have been calculated and discussed in detail after validating the proposed numerical approach. The longitudinal stresses in different sections have been discussed and verified with theoretical prediction. As the continuously work of the previous study on the effects of weld parameters on the thermal response, their effects on the structural response of butt-welded plates are included as well.

Research paper thumbnail of Mechanical properties assessment of specimens subjected to random non-uniform general corrosion and tensile load

The objective of this work is to analyze the strength and deformability of steel specimens subjec... more The objective of this work is to analyze the strength and deformability of steel specimens subjected to random non-uniform general corrosion and tensile load. The real shape of corrosion surface has been generated by a probabilistic model of corrosion deterioration. Non-linear, large deformation and threedimensional finite element analyses have been employed to analyze the mechanical properties of deteriorated specimens. The strength of corroded specimens is estimated as a function of the average corrosion depth and the minimum cross sectional area. The deformability and energy absorption of the corroded plates are estimated as a function of the surface roughness represented by the difference of averaged plate thickness and that at the section of minimum cross sectional area.

Research paper thumbnail of THERMO-MECHANICAL ANALYSIS OF THE EFFECTS OF WELD PARAMETERS IN SHIP PLATES DURING WELDING PROCESS

The objective of this work is to develop models and techniques for predicting the temperature fie... more The objective of this work is to develop models and techniques for predicting the temperature field and distortions induced in ship plates by the welding process. Finite Element models representative of real ship structures and components have been developed to simulate the transient thermal analysis with moving heat source model. Results have been compared to numerical and experimental results obtained by other researchers. The time variant temperature distributions obtained have been applied as thermal loads in mechanical analyses to predict the plate distortions. The study of the effects of different parameters on the welding response, including the torch speeds, heat inputs, thicknesses of plates has also been included. NOMENCLATURE ) r ( q Heat flux max q Maximum heat flux r Distance from heat source center Q Heat input R Radius of heating spot 1.