We present new quantitative model describing the pressure dependence of acoustic P-and S-wave velocities.Assuming that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can ...We present new quantitative model describing the pressure dependence of acoustic P-and S-wave velocities.Assuming that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand S-waves)velocity-pressure function.We estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity data.As is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are assumed.Increasing the number of exponential terms leads to highly nonlinear ill-posed inverse problem.Due to this reason,we develop the spectral inversion method(SIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as unknowns.The characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity data.The characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical cracks.This gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.展开更多
The activated TIG(ATIG) welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention.The shape of a weld in terms of its width-to-d...The activated TIG(ATIG) welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention.The shape of a weld in terms of its width-to-depth ratio known as aspect ratio has a marked influence on its solidification cracking tendency.The major influencing ATIG welding parameters,such as electrode gap,travel speed,current and voltage,that aid in controlling the aspect ratio of DSS joints,must be optimized to obtain desirable aspect ratio for DSS joints.Hence in this study,the above parameters of ATIG welding for aspect ratio of ASTM/UNS S32205 DSS welds are optimized by using Taguchi orthogonal array(OA)experimental design and other statistical tools such as Analysis of Variance(ANOVA) and Pooled ANOVA techniques.The optimum process parameters are found to be 1 mm electrode gap,130 mm/min travel speed,140 A current and 12 V voltage.The aspect ratio and the ferrite content for the DSS joints fabricated using the optimized ATIG parameters are found to be well within the acceptable range and there is no macroscopically evident solidification cracking.展开更多
The shape of the fusion zone after weld in terms of its width-to-depth ratio is known as the aspect ratio, large aspect ratios in welded joints usually results in cracks formation during solidification of the weld;it ...The shape of the fusion zone after weld in terms of its width-to-depth ratio is known as the aspect ratio, large aspect ratios in welded joints usually results in cracks formation during solidification of the weld;it also results in tensile residual stresses at the fusion zone. In this study, central composite design matrix was employed using Design Expert 7.01 software to optimize the aspect ratio of mild steel welded joint. A total of 20 sets of experiments were produced;the weld specimen was mild steel plate measuring 60 mm × 40 mm × 10 mm. TIG welding machine with 100% Argon Shielding Gas was used for this experiment and at the end of the experiment, an optimum weld aspect ratio of 0.646 was achieved using current of 140 amp, voltage of 25 volt and gas flow rate of 15 L/min. This value of 0.646 is expected to contain the minimum adequate molten metal just enough to make the desired bead penetration to form good aspect ratio at a minimum cost with appropriate weld quality and productivity. This would help minimize the formation of cracks after weld.展开更多
随着5G通信技术的逐步商用,通信类电子产品进入发展的快节奏,通信类PCB(含服务器、交换机、存储器等)随着高速信号的不断提升,其信号完整性成为了PCB制造商的最大挑战,高速材料的应用无法避免且等级越来越高,VIP(Via in Pad)以及背钻孔...随着5G通信技术的逐步商用,通信类电子产品进入发展的快节奏,通信类PCB(含服务器、交换机、存储器等)随着高速信号的不断提升,其信号完整性成为了PCB制造商的最大挑战,高速材料的应用无法避免且等级越来越高,VIP(Via in Pad)以及背钻孔设计成为主流并需要树脂进行填塞。集成密度的提升迫使PCB孔间距及孔径不断减小,厚径比不断提升;树脂塞孔工艺在高速材料等级不断提升以及厚径比AR越来越高背景下,树脂塞孔的孔内树脂裂纹成为行业痛点与共性问题,文章从塞孔树脂材料、塞孔固化工艺、通孔厚径比设计等方面,对树脂塞孔孔内裂纹形成机理进行分析研究,同时对于改善背钻孔与高厚径比通孔裂纹提出解决方案。展开更多
基金supported by the European Union,co-financed by the European Social Fund and the GINOP-2.315-2016-00010"Development of enhanced engineering methods with the aim at utilization of subterranean energy resources"project in the framework of the Szechenyi 2020 Plan,funded by the European Union,co-financed by the European Structural and Investment Funds。
文摘We present new quantitative model describing the pressure dependence of acoustic P-and S-wave velocities.Assuming that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand S-waves)velocity-pressure function.We estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity data.As is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are assumed.Increasing the number of exponential terms leads to highly nonlinear ill-posed inverse problem.Due to this reason,we develop the spectral inversion method(SIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as unknowns.The characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity data.The characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical cracks.This gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.
文摘The activated TIG(ATIG) welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention.The shape of a weld in terms of its width-to-depth ratio known as aspect ratio has a marked influence on its solidification cracking tendency.The major influencing ATIG welding parameters,such as electrode gap,travel speed,current and voltage,that aid in controlling the aspect ratio of DSS joints,must be optimized to obtain desirable aspect ratio for DSS joints.Hence in this study,the above parameters of ATIG welding for aspect ratio of ASTM/UNS S32205 DSS welds are optimized by using Taguchi orthogonal array(OA)experimental design and other statistical tools such as Analysis of Variance(ANOVA) and Pooled ANOVA techniques.The optimum process parameters are found to be 1 mm electrode gap,130 mm/min travel speed,140 A current and 12 V voltage.The aspect ratio and the ferrite content for the DSS joints fabricated using the optimized ATIG parameters are found to be well within the acceptable range and there is no macroscopically evident solidification cracking.
文摘The shape of the fusion zone after weld in terms of its width-to-depth ratio is known as the aspect ratio, large aspect ratios in welded joints usually results in cracks formation during solidification of the weld;it also results in tensile residual stresses at the fusion zone. In this study, central composite design matrix was employed using Design Expert 7.01 software to optimize the aspect ratio of mild steel welded joint. A total of 20 sets of experiments were produced;the weld specimen was mild steel plate measuring 60 mm × 40 mm × 10 mm. TIG welding machine with 100% Argon Shielding Gas was used for this experiment and at the end of the experiment, an optimum weld aspect ratio of 0.646 was achieved using current of 140 amp, voltage of 25 volt and gas flow rate of 15 L/min. This value of 0.646 is expected to contain the minimum adequate molten metal just enough to make the desired bead penetration to form good aspect ratio at a minimum cost with appropriate weld quality and productivity. This would help minimize the formation of cracks after weld.
基金Supported by the National Natural Science Foundation of China(No.50323044) and by a grantfrom Science & Technology Commission of Shanghai Municipality (No.05DJ14001)
文摘随着5G通信技术的逐步商用,通信类电子产品进入发展的快节奏,通信类PCB(含服务器、交换机、存储器等)随着高速信号的不断提升,其信号完整性成为了PCB制造商的最大挑战,高速材料的应用无法避免且等级越来越高,VIP(Via in Pad)以及背钻孔设计成为主流并需要树脂进行填塞。集成密度的提升迫使PCB孔间距及孔径不断减小,厚径比不断提升;树脂塞孔工艺在高速材料等级不断提升以及厚径比AR越来越高背景下,树脂塞孔的孔内树脂裂纹成为行业痛点与共性问题,文章从塞孔树脂材料、塞孔固化工艺、通孔厚径比设计等方面,对树脂塞孔孔内裂纹形成机理进行分析研究,同时对于改善背钻孔与高厚径比通孔裂纹提出解决方案。
