Structural Integrity Assessment by Using Cross-Correlated Modal Identification

Early researches on steel structures integrity were mainly oriented on calculations and conventional experiments. Robust numerical methods of a high accuracy are usually less reliable in estimation of dynamic properties and a true condition of a steel structure. On the other hand, experiments on real structures, being in regular operation, could be very demanding to conduct. Therefore, the implementation and justification of novel methodology in structural integrity analysis is presented here. The main idea is to correlate experimental results with those obtained applying ANSYS software package. Throughout a results cross-correlation and model adjustment the new presentation of the structure is created, involving natural frequency, modal mass, stiffness and damping. By a proper definition of those parameters, and a 3D model of the structure, a preliminary map of measuring points and measuring configuration are set in order to enable structural integrity assessment. Example of application of this procedure is given

Design and manufacture of reformer in polymer electrolyte membrane fuel cell

The paper describes the development and manufacturing aspects of the reformer in polymer electrolyte membrane (PEM) fuel cell, from the first step of realization that includes modelling the main parts of the reformer; analysing the reforming initial geometry, adopting changes in shape and dimensions caused by inaccessibility of tools during machining; and the manufacture of the reformer. Development and manufacturing are performed based on a model developed in SolidWorks (R). Based on this model, numerical analysis is performed in order to show the influence of geometry and its changes that affect reformer performance, and is not shown here. Adopted changes in the reformer design are presented, along with detailed explanation. Reformer processing is carried out on a milling machine and Wire EDM machine. The transversal hole diameter on the reformer is increased from 1 to 2 mm to reduce economic cost. Before processing, the tool path simulation is also performed. Beside the main subject, general data on proton exchange membrane fuel cell are introduced with a short description and explanations of the PEM function, method and purpose

Design and manufacture of reformer in polymer electrolyte membrane fuel cell

The paper describes the development and manufacturing aspects of the reformer in polymer electrolyte membrane (PEM) fuel cell, from the first step of realization that includes modelling the main parts of the reformer; analysing the reforming initial geometry, adopting changes in shape and dimensions caused by inaccessibility of tools during machining; and the manufacture of the reformer. Development and manufacturing are performed based on a model developed in SolidWorks (R). Based on this model, numerical analysis is performed in order to show the influence of geometry and its changes that affect reformer performance, and is not shown here. Adopted changes in the reformer design are presented, along with detailed explanation. Reformer processing is carried out on a milling machine and Wire EDM machine. The transversal hole diameter on the reformer is increased from 1 to 2 mm to reduce economic cost. Before processing, the tool path simulation is also performed. Beside the main subject, general data on proton exchange membrane fuel cell are introduced with a short description and explanations of the PEM function, method and purpose

Determination of the Actual Stress-Strain Diagram for Undermatching Welded Joint Using DIC and FEM

This paper presents new methodology for determining the actual stress-strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress-strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress-strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress-strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry

Effect of elevated temperatures on mechanical properties of ultra high strength hot work tool steel h11

This paper presents an experimental and numerical study into the influence of elevated temperatures on mechanical properties of the heat treated high quality hot work tool steel H11. This steel belongs to a group of alloyed steels with extraordinary mechanical properties. The aim of this study was to determine the highest temperature at which these properties are still maintained. The experimental investigation focused on the tensile testing of specimens at seven different temperatures, including the room temperature. The highest testing temperature was 700 degrees C. The heat treatment of plates (specimens) consisted of quenching and tempering. Although the strain hardening of this type of materials is small, the strain hardening curves were calculated to show if there was a possibility for the material to increase its strength due to exploitation loads. Also, a numerical analysis of the tensile test by using the finite element method was done in order to define an appropriate model for numerical testing. The obtained results are then compared with the experimental results

Comparative analysis of printing parameters effect on mechanical properties of natural PLA and advanced PLA-X material

FDM is a commercially widespread 3D printing technology which uses thermoplastic materials for building prototypes and functional parts. Most used materials in this technology are PLA (PolyLactic Acid) and ABS (Acrylonitrile Butadiene Styrene) materials which contain dissimilar mechanical properties and printing abilities. PLA is considered as a good material for prototypes and parts that acquire higher dimensional accuracy, and is considered as a material that is easier to print than ABS. Advantages of ABS material, compared to standard PLA are better mechanical properties, sufficiently higher printing speeds and higher heat resistivity. Deficiency of ABS over PLA is shrinking of ABS material after 3D printing-resulting in poor dimensional accuracy or failure during printing. A newly available material PLA-X ("mcPP", Mitsubishi Chemical, Japan) houses advantages of both mentioned materials and may lead to wider commercial and industrial use. Different printing parameters of the same material may lead to different mechanical properties of the finished part. The aim of this paper is to compare how different printing parameters effect on mechanical properties of standard PLA and PLA-X-which is a material that has similar dimensional accuracy of finished parts as PLA and possesses higher mechanical properties like ABS. Samples of PLA and PLA-X where printed in five different printing regimes, varying layer height, number of outline perimeters, infill density and sample humidity, with five samples each (according to ISO 527-2 international standard) and used for mechanical testing on standard tensile testing machine

Effect of Elevated Temperatures on Mechanical Properties of Ultra High Strength Hot Work Tool Steel H11

This paper presents an experimental and numerical study into the influence of elevated temperatures on mechanical properties of the heat treated high quality hot work tool steel H11. This steel belongs to a group of alloyed steels with extraordinary mechanical properties. The aim of this study was to determine the highest temperature at which these properties are still maintained. The experimental investigation focused on the tensile testing of specimens at seven different temperatures, including the room temperature. The highest testing temperature was 700 °C. The heat treatment of plates (specimens) consisted of quenching and tempering. Although the strain hardening of this type of materials is small, the strain hardening curves were calculated to show if there was a possibility for the material to increase its strength due to exploitation loads. Also, a numerical analysis of the tensile test by using the finite element method was done in order to define an appropriate model for numerical testing. The obtained results are then compared with the experimental results

Determination of the Actual Stress-Strain Diagram for Undermatching Welded Joint Using DIC and FEM

This paper presents new methodology for determining the actual stress-strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress-strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress-strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress-strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry

Comparative analysis of printing parameters effect on mechanical properties of natural PLA and advanced PLA-X material

FDM is a commercially widespread 3D printing technology which uses thermoplastic materials for building prototypes and functional parts. Most used materials in this technology are PLA (PolyLactic Acid) and ABS (Acrylonitrile Butadiene Styrene) materials which contain dissimilar mechanical properties and printing abilities. PLA is considered as a good material for prototypes and parts that acquire higher dimensional accuracy, and is considered as a material that is easier to print than ABS. Advantages of ABS material, compared to standard PLA are better mechanical properties, sufficiently higher printing speeds and higher heat resistivity. Deficiency of ABS over PLA is shrinking of ABS material after 3D printing-resulting in poor dimensional accuracy or failure during printing. A newly available material PLA-X ("mcPP", Mitsubishi Chemical, Japan) houses advantages of both mentioned materials and may lead to wider commercial and industrial use. Different printing parameters of the same material may lead to different mechanical properties of the finished part. The aim of this paper is to compare how different printing parameters effect on mechanical properties of standard PLA and PLA-X-which is a material that has similar dimensional accuracy of finished parts as PLA and possesses higher mechanical properties like ABS. Samples of PLA and PLA-X where printed in five different printing regimes, varying layer height, number of outline perimeters, infill density and sample humidity, with five samples each (according to ISO 527-2 international standard) and used for mechanical testing on standard tensile testing machine