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  • 1.
    Al Choueyri, Yousef
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Fayazi, Mojtaba
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Digital models of manufacturing: with emphasis on titanium welding for early product development2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is part of the BTH research lab, focusing on developing the early product development, by analyzing how to integrate the manufacturing process with the early design process. A known problem in the manufacturing industry is the knowledge gap between the designers and the manufacturing process. Where in the early stages of the product development a knowledge regarding the manufacture process is needed. This is in many cases ignored by the designers because it is commonly thought that the responsibility of selecting the manufacturing processes for a product falls upon the manufacturers, despite the fact that the manufacturing processes in reality is highly dependent upon the design choses such as materials, size, shape, finishing and tolerances of the product. To mitigate this problem a variations of product ‘team’ approaches have been used where the idea is to involve a multitude of people with the necessary experience to produce a ‘production friendly product’. Those approaches have a few drawbacks mainly the problem of finding people with the relevant experiences or that the expertise only covers the manufacturing processes already used in the organization, losing the opportunity to benefit from any alternative manufacturing process.

    This thesis focuses on how the welding manufacturing technic, analysis can be integrated into the design process with the help of a digital model?

    To improve the communications between the manufacturers and designers, two excel files were developed. The first excel file aimed at the manufacturers where they can present the specific machines used in the workshop. Focusing on specific machine and workshops instead of on the general welding method will give the designers a better understanding of the feasibility of producing their design in a specific workshop instead of focusing on a specific manufacturing method.

    The second excel file is aimed at calculating and comparing the weld methods where the cost and requirements are derived for general welding methods and compared with the machine specifications gathered from the manufacturers using the first excel file. To assess the excel files, a parametrized CAD model of the rear engine turbine structure was developed, and three different cases were used to evaluate the developed excel files.

    The values used are presented in Appendix A: Table 11–15, and were gathered from public sources. Values were also approximated using regression analysis.

  • 2.
    Andreasson, Eskil
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Lindström, Tommy
    Lunds Universitet, SWE.
    Käck, Britta
    Altair Engineering AB, SWE.
    Malmberg, Christoffer
    Saab AB, SWE.
    Asp, Ann Magret
    Tetra Pak AB, SWE.
    Simulation of thin aluminium-foil in the packaging industry2017In: AIP Conference Proceedings / [ed] Brabazon D.,Ul Ahad I.,Naher S., American Institute of Physics Inc. , 2017, Vol. 1896, article id 160014Conference paper (Refereed)
    Abstract [en]

    This work present an approach of how to account for the anisotropic mechanical material behaviour in the simulation models of the thin aluminium foil layer (≈10 μm) used in the Packaging Industry. Furthermore, the experimental results from uniaxial tensile tests are parameterised into an analytical expression and the slope of the hardening subsequently extended way beyond the experimental data points. This in order to accommodate the locally high stresses present in the experiments at the neck formation. An analytical expression, denominated Ramberg-Osgood, is used to describe the non-linear mechanical behaviour. Moreover it is possible with a direct method to translate the experimental uniaxial tensile test results into useful numerical material model parameters in Abaqus™. In addition to this the extended material behaviour including the plastic flow i.e. hardening, valid after onset of localisation, the described procedure can also capture the microscopic events, i.e. geometrical thinning, ongoing in the deformation of the aluminium foil. This method has earlier successfully been applied by Petri Mäkelä for paperboard material [1]. The engineering sound and parameterised description of the mechanical material behaviour facilitates an efficient categorisation of different aluminium foil alloys and aid the identification of the correct anisotropic (RD/TD/45°) mechanical material behaviour derived from the physical testing. © 2017 Author(s).

  • 3.
    Aniol, Alexander
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics.
    How firms can reduce the risks with fixed price contracts2017Independent thesis Advanced level (degree of Master (One Year)), 300 HE creditsStudent thesis
    Abstract [en]

    Firms have had difficulties in dealing with the risks that occur when providing fixed price contracts (FP) for both small – scale and large – scale projects to involved customers. This is general for the most companies surveying customers with the development for a product or service in the IT – industry. Research has paid minimum attention on how firms can imple-ment scientific proven agile methods to reduce the risks with FP contracts to increase profit margin. In FP contracts, the risks lie on the supplier providing the contract, where research has shown that companies have issues in determining the project scope in the planning pro-cess and how they can find certain approaches for increasing the dialogue in a buyer and seller arrangement. Therefore, firms are more comfortable in going into Time and Material (T&M) arrangements where customers pay for the time and resources spent under a project process. This study also makes investigations on how firms can make accurate estimations of the development durations that occurs when providing this contracting form and how firms can identify risks into profitable pricing engagements. The study took ground in Lund, Swe-den at a company named Sigma Connectivity which is a firm developing services and prod-ucts based on wireless communication and the phenomenon called Internet Of Things (IoT).The delimitations that were made for this study was related to the marketing mix concept which conducts of seven strategies for business management of these seven strategies the choice was made to exclude exclude sustainable aspects, physical evidence, internal market-ing related to promotion, and location factors. Internal qualitative directive and semi – struc-tured interviews were methods used for determining variables and key issue with FP contracts that was included in the survey based approach to customers. Agile methods such as Feature Driven Development (FDD) and Work Breakdown Structure (WBS) were implemented in or-der to tackle the challenges of visualising a clear project scope description with clear specifi-cation on what is included in a FP contracts in small – scale and large – scale projects.The results conducted from this study shows that integrating scientific proven methods such as FDD and WBS in a firm, will help them to divide project processes into smaller mecha-nisms, which will provide sufficient access for an increased project scope allocation forcing the involved parties in a buyer and seller arrangement to hold both internal and external re-views which will enable the possibility of making pricing approaches during the project pro-cess. Results also shows that customers find FP contracts to be the most valuable but the diffi-culties that they have felt in this arrangement is to incorporate new ideas for a project scope change during a project process. The use of the FDD framework and WBS provided results that are vital for firms going into FP arrangements where clearer project scope definitions, key role identifications, increased pricing opportunities and communication channels were founded.Keywords: Fixed price contracts (FP), project scope, Work Breakdown Structure (WBS), Feature Driven development (FDD).

  • 4.
    Devotta, Ashwin Morris
    et al.
    Sandvik Coromant Sverige AB, SWE.
    Sivaprasad, Palla Venkata
    Sandvik Materials Technology, SWE.
    Beno, Tomas
    Högskolan Väst, SWE.
    Eynian, Mahdi
    Högskolan Väst, SWE.
    Hjertig, Kjell
    Högskolan Väst, SWE.
    Magnevall, Martin
    Lundblad, Mikael
    Sandvik Coromant Sverige AB, SWE.
    A modified johnson-cook model for ferritic-pearlitic steel in dynamic strain aging regime2019In: Metals, ISSN 2075-4701, Vol. 9, no 5, article id 528Article in journal (Refereed)
    Abstract [en]

    In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s-1, 5 s-1, and 60 s-1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

  • 5.
    Falk, Johannes
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Fracture prediction of stretched shear cut edges in sheets made of Dual-Phase steel2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Dual-Phase (DP) steels, part of the group of Advanced High Strength Steels (AHSS), are used by car manufactures due to its large strength to weight ratio. The high strength of the DP steel does have a negative impact on the formability during sheet metal forming and stretch forming, e.g. fractures often appear in shear cut edges during forming of blanks made of DP steel.

     

    The main objective with this thesis is to develop a new punch for Volvo Cars that concentrates the strain to the sheared edges of a test specimen made from different types of DP steel. This is done to be able to measure and obtain maximum fracture strain during stretch forming tests in a press. The newly developed test method is called CTEST (Concentrated Trim Edge Strain Test).

     

    The tests are performed with DP steel specimens with three different qualities of the shear cut edges; fine cut, medium cut and worn cut. DP steels tested are DP600GI, DP600UC and DP800GI from three different suppliers. 10 different types of DP steels are tested in this study with different thickness. Thickness of specimens tested are 1 mm, 1.1 mm, 1.5 mm and 2 mm and all specimens tested have a lengthwise (RD) rolling direction.

     

    The quality of the sheared cut edge has a great impact to the formability and maximum fracture strain of the specimen. A specimen with a fine cut endures higher fracture strain than medium cut and a worn cut for all types of DP steel with different thickness. A 1 mm thick specimen endures a lower fracture strain than 1.5 mm and 2 mm specimen for all cut qualities.

     

    Further, the impact of the orientation of the burr zone of a shear cut edge is studied. With the burr zone facing upwards from the CTEST punch the formability of the specimens is decreased compared to a burr zone facing downwards, especially for a worn cut specimen with micro cracks and imperfections in the edge surface.

     

    ARAMIS Digital Image Correlation (DIC) system is used to analyze the specimen edges during press experiments. The ARAMIS results unveil that several small fractures appear in the sheared edges of a specimen just before the specimens split into two pieces. This phenomenon was seen for specimen with worn and medium shear cut qualities.

     

    Finite Element (FE) simulations of the CTEST is performed in AutoForm to determine maximum values of the true strain for the three different cut qualities. The simulation in AutoForm does show a slightly higher value of the force and press depth than the value from the press test before maximum fracture strain in reached. The small fractures seen in ARAMIS just before the specimen split into two pieces cannot be seen in the simulation in AutoForm.

  • 6.
    Hallstedt, Sophie
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Strategic Sustainable Development.
    Isaksson, Ola
    Chalmers University of Technology, SWE.
    Material criticality assessment in early phases of sustainable product development2017In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 161, p. 40-52Article in journal (Refereed)
    Abstract [en]

    Improving structural performance of products is often realized by introducing increasingly advanced and complex materials as well as material combinations. What material to use in products is decided in the early product development phases and has a decisive impact for manufacturing, maintenance and end-of-life. A particular challenge is that the decisions need to be made upfront, where information of the forthcoming product is limited. This paper presents an early product development method to assess the criticality of alloy materials from a resource availability- and sustainability perspective. The method distinguishes itself from previous studies that focus on element criticality on a country level. The method is used to characterize and analyze the criticality of alloys in a three-step process that aims to support product design teams selecting what material alloy to use in early phases of design. It provides a proactive and systematic approach related to critical materials to avoid potential future problems on a long-term basis. The method presented has been developed in an action research-based approach in an aerospace company where a product design team validated and evaluated the material criticality method. The generic nature of the method is likely to be applicable not only to aerospace companies but also to other industries using advanced alloys. An important finding from applying the method in the company case was the clear link between long term business impact and sustainability performance. © 2017 Elsevier Ltd

  • 7.
    Karlsson, Hampus
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Karlsson, Anton
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Konceptutveckling av en caterpillar med inriktning på kvalitet: En utvecklingsprocess2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When transporting a sea cable, what is commonly called a caterpillar is used, but the most common said is a cable tensioner. These machines can be found in a flurry of different variants, where there are a multitude of competitors, which applies demands to having an extremely distinctive machine. Therefore  from  a  market  analysis  it  have  been  identified  that  a  lack  of  quality  regarding  the machines are a factor. A poor quality shortage that usually occurs in hard weather conditions, but this is something that should not happen as it may lead to machine breakdown.

    Semcon AB in Karlskrona constructs and then collaborates with Ronneby Svets & Smide, who manufacture cable carousels, armrests and other equipment for the cable industry but not the cable tensioner that are ordered separately by external companies. This is the background to why the project is created because Semcon sees a need to eliminate this bottleneck and also expand their product portfolio for customer recovery. The aim it therefore, together with Semcon, develop a new concept for a completely  new cable tensioner with given preferences, rough drawing and selection of qualitative features for the machine in order to be competitive with its future overall solution for the cable industry.   

    To find a solution to the described problem, a product development process has been followed to establish  structure.  The  process  include  a  planning,  concept  development,  design  and  detailed development phase. From the first phase, a wide understanding of how the complex machine works and where its deficiencies may be. Even hidden customer needs in form of interviews with cable manufacturers in Karlskrona and with industries that handle sea cable were conducted to get a broader spectrum. The needs are transformed into specifications to generate concepts based on the rankings of the measurably formulated specifications. Followed up by an evaluation where the best concepts were taken to the design phase and detailed development. All design calculations have been made, either by hand or with computer-based programs.  

    The work has resulted in an innovative concept of a whole cable tensioner with all key components, rough drawing, together with a new thinking solution regarding the contact face between the cable and the machine, developed through experiments and theory studies. As this project is very broad, the overall project has been divided into two master thesis works and all electronics are handles by  an  electrical/automation  company.  Therefore,  for  a  broader  understanding  and  information about functionality, reference is made to the second project “Konceptutveckling kring funktionerna hos en kabeldragare” authored by Anton Hansson.  

    It is extremely important to mention that the outcome of this project is intended to be a concept for a new innovative cable tensioner. This means that with future work on the concept, which includes  continued  depth  of  calculation  and  further  contact  with  suppliers,  can  provide  an opportunity  to  manufacture  the  generated  concept.  Another  development  area  Semcon  must proceed with is to review the safety routines of the machine. The authors of this report believe that a highly competitive solution has been presented, and that work contributes to a strong foundation for  the  development  of  transporting  sea  cable  technology  in  the  future  with  the  help  of  this innovative concept.

  • 8.
    Kianian, Babak
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Tavassoli, Sam
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics.
    Larsson, Tobias
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Diegel, Olaf
    The Adoption of Additive Manufacturing Technology in Sweden2015In: 3D Printing and Additive Manufacturing, ISSN 2329-7662, Vol. 2, no 4, p. 152-158Article in journal (Refereed)
    Abstract [en]

    This article analyzes the adoption of additive manufacturing (AM) technologies in Sweden. The data set consists of a recent and representative sample of Swedish AM users (companies, universities, and research institutes). The authors investigate two questions. First, what are the current applications of AM in Sweden (e.g., rapid prototyping [RP], production)? Second, what are the factors that can explain the variation in AM adoption among the users? Using a regression analysis technique, the main findings are as follows. (i) There is a variation among users' choice of AM application, and the majority of users are expanding their AM applications beyond RP. (ii) There are two factors that positively affect the decision of firms to expand classical RP and incorporate production and management as well. These two factors are using multiple AM technologies (as opposed to single fused deposition modeling technology) being small companies. The authors discuss the implication of these results.

  • 9. Li, JIan
    et al.
    Kao-Walter, Sharon
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    The friction and wear properties of Polypropylene composite filled with carbon fiber and Polyamide 62014In: Journal of Thermoplastic Composite Materials, ISSN 0892-7057, E-ISSN 1530-7980, Vol. 27, no 8, p. 1037-1044Article in journal (Refereed)
    Abstract [en]

    Carbon fiber composites were prepared in order to study the influence of fillers (polyamide 6; PA6) on the tensile and tribological properties of polypropylene (PP) composites. Tensile fracture mechanism was discussed based on the tensile testresults. Tribological tests were conducted on a Mobile Remote Handler-3 (MRH-3) friction and wear tester using a block-on-ring arrangement. It was observed that the carbon fiber (CF) played a main role in the tensile-resistant and wear-resistant properties of the CF/PP composites. The tensile properties were ruled by the fiber–matrix adhesion. Moreover, the excellent tribological performance of the CF/PA6/PP composite is consistent with the worn surface morphology shown.

  • 10.
    Nilsson, Peter
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Measuring material properties of thin films with DIC and tearing test of laminate2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Thin polymer materials are today widely used in industry and production. An ordinary food package can have around six different layers of materials laminated together to obtain the desired protection. To obtain an efficient usage of these materials simulations are often required. But the simulations require precise and good material models and properties. To obtain these properties through standard tests are difficult as normal strain gauges or extensometers can’t be used. Much research has been done on this kind of material. But still, the knowledge of the behaviour in certain cases is limited. One such area is the tearing of a laminated material.

     

    The first objective of the work is to test a new measurement method, Digital Image Correlation (DIC), for thin polymer films and test if the method is applicable. DIC is a non-contact measurement technique that measure the deformation of a stochastic pattern. The strain is then calculated from this deformation. These strains can then be used to obtain material properties and behaviour. The second objective is to test the tearing behaviour of a laminate.

     

    The material used is a laminate between a PET (100 μm) and LDPE (25 μm) film. When testing the single layers they were carefully delaminated with a plexiglass staff. As the material can be anisotropic the materials were tested in five directions: Machine Direction (MD); 22,5˚; 45˚; 67,5˚ and Cross Direction (CD). The work and tests were performed at BTH Campus Gräsvik.

     

    An experimental setup for DIC with the usage of chalk spray and backlight was tested. Five tests were performed with and without DIC pattern. It was calculated that the DIC specimens were within standard deviation of the reference tests. GOM Correlate was used to evaluate the strains and visualise the distribution. The strains obtained were also used to calculate the true stress of the specimens and estimate the Poisson’s ratio.   

     

    Through testing it was concluded that the tearing of the laminate led to delamination in one of the legs. The delamination always appears in the leg where the LDPE film will experience tensile forces. The crack also angels towards 45˚. By testing single layers it was found that the PET film angles when teared, likely caused by the anisotropy of the material.   

     

    An experimental setup for the use of DIC for thin polymer has been developed. This method can be used for future measurements and improvement of material models. The behaviour of laminated tearing was observed and some conclusions could be drawn about its behaviour. However, a lot more work is required on this subject.

  • 11.
    Pilthammar, Johan
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Sigvant, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Kao-Walter, Sharon
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Introduction of elastic die deformations in sheet metal forming simulations2018In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 151, no S1, p. 76-90Article in journal (Refereed)
    Abstract [en]

    Simulations of sheet metal forming (SMF) with finite element models (FE-models) for stamped parts in the car industry are useful for detecting and solving forming problems. However, there are several issues that are challenging to analyze. Virtual tryout and analyzes of stamping dies in running production are two important cases where many of these challenging issues are present. Elastic deformations of dies and press lines and a physically based friction model is often missing when these types of cases are analyzed. To address this, this research aims to develop a method wherein the results of two separate FE-models are combined to enable SMF simulations with the inclusion of elastic tool and press deformations. The two FE-models are one SMF model with two-dimensional (2D) rigid tool surfaces and one structural model of the die and press. The structural model can predict surface shapes and pressure distributions for a loaded stamping die. It can also visualize relatively large and unexpected deformations of the die structure. The recommended method of transferring the deformations from the structural model to the 2D surfaces is through an FE technique called submodeling. The subsequent SMF simulations show that the method for calculating and using the deformed surfaces together with the TriboForm friction model yields a result that matches measured draw-in and strains. It is verified that the ability to virtually deform a die and include the resulting geometry in forming simulations is of high importance. It can be used for the virtual tryout and optimization of new dies or analyses of existing dies in running production. It is suggested that future research focus on a more efficient and automated workflow. More experimental data and simulations are also needed to verify the assumptions made for the simulation models. This will enable the method to be adopted in a reliable way for standard SMF simulations. © 2017.

  • 12.
    R Lacno, Jeronimo
    Blekinge Institute of Technology. Höganäs AB.
    Förbättrad korrosionmetod för Höganäs AB lödningslegeringar2017Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    This report summarizes and compares two different corrosion methods, Höganäs internal corrosion test and a corrosion test according to VDA 230-214. The goal has been to develop a new method that solves Höganäs problems with repeatability with these two tests as a background. By carefully studying the process of brazing, acid preparation, corrosion testing for 4 weeks and the microstructure testing process on the brazed joint, you have managed to get a quantitative result.

    The improvement of the internal corrosion method was chosen to be based on the sulfuric acid and preparing acid solutions by controlling the pH value between an aggressive and a less aggressive value. It was also chosen to compare two products that has the same corrosion properties, Brazelet F300 and Brazelet Ni613. The difference between F300 and Ni613 is that the F300 contains iron and less nickel. Previous investigations have been made to compare these products but have shown different results.

    This investigation has led to a method of quantifying the corrosion resistance of the different brazing instead of only visually judging whether the corrosion resistance is good or bad. This method will be used for future work to investigate other acids.

  • 13.
    Rudenko, Oleg
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering. Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
    Hedberg, Claes
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering. Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science. Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering. Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences. Blekinge Institute of Technology, Department of Telecommunications and Mathematics.
    A new equation and exact solutions describing focal fields in media with modular nonlinearity2017In: Nonlinear dynamics, ISSN 0924-090X, E-ISSN 1573-269X, Vol. 89, no 3, p. 1905-1913Article in journal (Refereed)
    Abstract [en]

    Brand-new equations which can be regarded as modifications of Khokhlov–Zabolotskaya–Kuznetsov or Ostrovsky–Vakhnenko equations are suggested. These equations are quite general in that they describe the nonlinear wave dynamics in media with modular nonlinearity. Such media exist among composites, meta-materials, inhomogeneous and multiphase systems. These new models are interesting because of two reasons: (1) the equations admit exact analytic solutions and (2) the solutions describe real physical phenomena. The equations model nonlinear focusing of wave beams. It is shown that inside the focal zone a stationary waveform exists. Steady-state profiles are constructed by the matching of functions describing the positive and negative branches of exact solutions of an equation of Klein–Gordon type. Such profiles have been observed many times during experiments and numerical studies. The non-stationary waves can contain singularities of two types: discontinuity of the wave and of its derivative. These singularities are eliminated by introducing dissipative terms into the equations—thereby increasing their order. © 2017 The Author(s)

  • 14.
    Sigvant, Mats
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Pilthammar, Johan
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Hol, Jeroen
    TriboForm Engineering, NLD.
    Wiebenga, J. H.
    TriboForm Engineering, NLD.
    Chezan, T.
    Tata Steel, NLD.
    Carleer, Bart
    AutoForm Engineering, DEU.
    Van Den Boogaard, A. H.
    University of Twente, NLD.
    Friction and lubrication modeling in sheet metal forming simulations of a Volvo XC90 inner door2016In: IOP Conference Series: Materials Science and Engineering, 2016, Vol. 159, no 1, article id 012021Conference paper (Refereed)
    Abstract [en]

    The quality of sheet metal formed parts is strongly dependent on the tribology, friction and lubrication conditions that are acting in the actual production process. Although friction is of key importance, it is currently not considered in detail in stamping simulations. This paper presents a selection of results considering friction and lubrication modeling in sheet metal forming simulations of the Volvo XC90 right rear door inner. For this purpose, the TriboForm software is used in combination with the AutoForm software. Validation of the simulation results is performed using door inner parts taken from the press line in a full-scale production run. The results demonstrate the improved prediction accuracy of stamping simulations by accounting for accurate friction and lubrication conditions, and the strong influence of friction conditions on both the part quality and the overall production stability. © Published under licence by IOP Publishing Ltd.

  • 15.
    Tabourot, Laurent
    et al.
    Universite Savoie Mont Blanc, FRA.
    Charleux, Ludovic
    Universite Savoie Mont Blanc, FRA.
    Balland, Pascale
    Universite Savoie Mont Blanc, FRA.
    Sène, Ndèye Awa
    Universite Cheikh Anta Diop, SEN.
    Andreasson, Eskil
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Experimental characterization and microstructure linked modeling of mechanical behavior of ultra-thin aluminum foils used in packaging2018In: PROCEEDINGS OF 21ST INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING (ESAFORM 2018), American Institute of Physics Inc. , 2018, Vol. 1960, article id UNSP 170016Conference paper (Refereed)
    Abstract [en]

    This paper is based on the hypothesis that introducing distribution of mechanical properties is beneficial for modeling all kinds of mechanical behavior, even of ordinary metallic materials. To bring proof of its admissibility, it has to be first shown that modeling based on this assertion is able to efficiently describe standard mechanical behavior of materials. Searching for typical study case, it has been assessed that at a low scale, yield stresses could be strongly distributed in ultrathin aluminum foils used in packaging industry, offering opportunities to identifying their distribution and showing its role on the mechanical properties. Considering initially reduced modeling allow to establish a valuable connection between the hardening curve and the distribution of local yield stresses. This serves for finding initial value of distribution parameters in a more sophisticated identification procedure. With finally limited number of representative classes of local yield stresses, concretely 3 is enough, it is shown that a 3D finite element simulation involving limited numbers of elements returns realistic behavior of an ultrathin aluminum foil exerted to tensile test, in reference to experimental results. This gives way to large possibilities in modeling in order to give back complex experimental evidence. © 2018 Author(s).

  • 16.
    Xu, Fei
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Li, C.R.
    Jiang, T.M.
    Zhang, D.P.
    Fatigue Life Prediction for PBGA under Random Vibration Using Updated Finite Element Models2016In: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 40, no 5, p. 1421-1435Article in journal (Refereed)
    Abstract [en]

    A procedure based on finite element (FE) modeling, response surface-based model updating and random vibration analysis is presented to predict the fatigue life of plastic ball grid array (PBGA) components mounted on daisy chain printed circuit board (PCB). A specially designed fixture is used to mimic the typical boundary condition of plug-in PCBs. The FE model is updated through three consecutive stages. In each stage, the first three resonant frequencies are calculated using ANSYS and correlated with modal test results. Two objective functions are created using resonant frequencies and minimized using a multi-objective genetic algorithm (MOGA). The results show that commercial FE software can be used to improve the accuracy of the FE model in a practical way. Random vibration analysis is performed and good agreement with test result is obtained. The resistance of the specially designed daisy chain PCB is monitored. A two-parameter Weibull distribution is used to fit the PBGA failure time. The Von Mises stress power spectral density (PSD) of the critical solder joints is calculated in ANSYS and transferred into time-history data. The rainflow cycle counting (RFCC), the S–N curve and the Miner’s rule are used to estimate the cumulative damage. The calculated fatigue life agrees well with the test results.

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