| 1. |
- Asbjørn Sörensen, Charlotte, et al.
(författare)
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Material selection - A qualitative case study of five design consultancies
- 2017
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Ingår i: Proceedings of the International Conference on Engineering Design, ICED. - : The Design Society. - 2220-4334. ; 1:DS87-1, s. 439-448, s. 439-448, s. 439-448
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Tidskriftsartikel (refereegranskat)abstract
- This qualitative case study aims at understanding when and how industrial designers, working in design consultancies, engage in activities that will influence material selection in the design process. While the extant literature presents material selection processes as a sequence of activities aimed at finding candidate materials, there is paucity of research on material criteria activities. Formulating material criteria is an activity that is performed during all design phases and they become clearer and more complete throughout the project. For the case studies, explorative semi-structured interviews were conducted with five industrial designers with 10 years of work experience or more. The results suggest (a) that risk management has a major influence on the material selection process, (b) that negotiations of project boundaries in the 'fuzzy' pre-design phase has crucial influence on the risk management aspect of the material criteria activities, and (c) a lack of awareness that design briefs usually outline material criteria expressed as sensorial characteristics, which are later translated by engineering into final material criteria used for the material selection process.
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| 2. |
- Hallstedt, Sophie, 1969-, et al.
(författare)
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Material criticality assessment in early phases of sustainable product development
- 2017
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 161, s. 40-52
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 3. |
- Huo, Xiaole, et al.
(författare)
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Effect of ultrasonic vibration on static properties of 5A06 aluminum alloy self-piercing riveting joints
- 2023
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Ingår i: Cailiao Kexue yu Gongyi/Material Science and Technology. - : Harbin Institute of Technology. - 1005-0299. ; 31:2, s. 44-49
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Tidskriftsartikel (refereegranskat)abstract
- Self-piercing riveting process is a new connection technology with excellent performance, green, and high efficiency. It can realize the connection of the similar, different, and multi-layer light alloy sheet materials and is widely used in new energy vehicles and other fields. Furthermore, it is becoming one of the critical technologies for achieving a lightweight body. However, because the self-piercing riveting joint is a typical tight connection component, fretting damage is prone to occur under the action of alternating stress or vibration, resulting in premature joint fatigue failure. This paper uses 5A06 aluminum alloy sheet material to carry out self-piercing riveting and ultrasonic self-piercing riveting composite connection tests under different ultrasonic welding tool heads. Based on the tensile-shear and electron microscope tests, the effect of ultrasonic vibration on the static properties of 5A06 aluminum alloy self-piercing riveted joints was studied. The results show that: ultrasonic vibration can effectively improve the static properties of self-piercing riveted joints; the ultrasonic metal welding will form a solid phase of welding between the sheets during the composite self-piercing riveting, which is the fundamental reason for improving the mechanical properties of the combined joint; the area of ultrasonic metal welding joints affects the mechanical properties of self-piercing riveted joints; the degree of ultrasonic solid-phase welding is higher when the welding area is more extensive; ultrasonic welding will increase the temperature of the rivet, which will affect the stability of the joints to a certain extent. © 2023 Harbin Institute of Technology. All rights reserved.
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| 4. |
- Li, Cheng-Wang, et al.
(författare)
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Comparison of mechanical properties of various joining processes of aluminum-titanium light alloy
- 2023
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Ingår i: Suxing Gongcheng Xuebao/Journal of Plasticity Engineering. - : Beijing Res. Inst. of Mechanical and Elec. Technology. - 1007-2012. ; 30:8, s. 138-145
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Tidskriftsartikel (refereegranskat)abstract
- 5A06 aluminum alloy and TA1 titanium alloy were selected for the connection tests of flow drill screw, ultrasonic clinch and ultrasonic self-piercing riveting. The influence of plate overlap methods on mechanical properties of each group of joints was studied by static tensile tests. The results show that the mechanical properties of the flow drill screw joints and the ultrasonic self-piercing riveted joints are significantly improved when the soft plate is on top during the riveting process. The plate overlap method has little effect on the ultrasonic clinch joint. Flow drill screw joints have the best cushioning and shock absorption performance, but the stability is poor, and it is more limited when applied to body structures. Ultrasonic clinch joints have low cost and simple process, but poor shear resistance and are not suitable for body structures subjected to high stress. Compared with the other two connection methods, the ultrasonic self-piercing riveted connection has the best stability, the best tensile resistance and shear stiffness, and is suitable for much of the structure in lightweight field of automobile body. © 2023 Beijing Res. Inst. of Mechanical and Elec. Technology. All rights reserved.
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| 5. |
- Reheman, W., et al.
(författare)
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Phase Field Modelling of Formation and Fracture of Expanding Precipitates
- 2017
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Ingår i: Procedia Structural Integrity. - : Elsevier BV. - 2452-3216. ; 3, s. 477-483
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Tidskriftsartikel (refereegranskat)abstract
- It is a common belief that embedded expanding inclusions are subjected to an internal homogeneous compressive hydrostatic stress. Still, cracks that appear in precipitates that occupy a larger volume than the original material, are frequently observed. The appearance of cracks has since long been regarded as a paradox. In the present study it is shown that matrix materials that increases its volume even several percent during the precipitation process develop a tensile hydrostatic stress in the centre of the precipitate. This is the result of a complicated mechanical-chemical phase transformation process. The process is here studied using a Landau phase feld model. Before the material is transformed and incorporated in a precipitate it undergoes stretching beyond the elastic strain limit because of the presence of already expanded material. During the phase transformation, the accompanying volumetric expansion cannot be fully accommodated which instead creates an internal compressive stress and adds tension in the surrounding material. As the growth of the precipitate proceeds, a region with increasing tensile stress develops in the interior of the precipitate. This is suggested to be the most probable cause of the observed cracks. First the mechanics that lead to the tension is computed. The infuence of elastic-plastic properties is studied both for cases both with and without cracks. The growth history from microscopic to macroscopic precipitates is followed and the result is compared with observations of so called hydride blisters that are formed on surfaces of zirconium alloys in the presence of hydrogen. A common practical situation is when the zirconium is in contact with an object of lower temperature. Then the cooled spot attracts hydrogen that make the zirconium transform to a metal hydride with the shape of a blister. The simulations predicts a final size and position of the growing crack that compares well with the experimental observations.
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| 6. |
- Rudenko, Oleg, et al.
(författare)
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A new equation and exact solutions describing focal fields in media with modular nonlinearity
- 2017
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Ingår i: Nonlinear dynamics. - : Springer Netherlands. - 0924-090X .- 1573-269X. ; 89:3, s. 1905-1913
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Tidskriftsartikel (refereegranskat)abstract
- 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)
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| 7. |
- Tuan Pham, Quoc, et al.
(författare)
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An evaluation method for experimental necking detection of automotive sheet metals
- 2023
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Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP. - : IOP PUBLISHING LTD.
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Konferensbidrag (refereegranskat)abstract
- In sheet metal stamping, the occurrence of strain localization in a deformed sheet is considered a failure. As so, sheet metal's formability is conventionally evaluated using the Forming Limit Diagram (FLD), which separates the principal strain space into safety and unsafety regions by a Forming Limit Curve (FLC). This study presents an evaluation method for detecting strain localization based on Digital Image Correlation (DIC) during the experiment. The commercial DIC software ARAMIS is adopted to monitor the strain-field distribution on the deformed specimen's surface. A detailed analysis of the proposed method is presented considering Nakajima tests conducted for two automotive sheet metals: AA6016 and DP800. The identified FLC based on the proposed method is compared with that of well-established methods such as ISO 12004:2-2008 and time-dependent methods. For both investigated materials, the proposed method presents a lower FLC than the others.
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| 8. |
- Islam, Md. Shafiqul, 1984-, et al.
(författare)
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Study of Ligament Length Effect on Mode Mix of a Modified In-Plane Shear Test Specimen
- 2016
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Ingår i: Materials Performance and Characterization. - California, USA : American Society for Testing and Materials. - 2379-1365 .- 2165-3992. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Shear fracture toughness is an important material behavior that needs to be determined and considered in many industrial fields. At the same time, shear testing is one of the complex material testing areas where available methods are few, often need special arrangements, and most of the methods do not strictly satisfy the definition of pure shear. In this study, a modified shear test specimen was proposed to measure the shear fracture toughness by uniaxial loading in a tensile testing machine. High density polyethylene (HDPE) was used as test material for the experiments. The specimen was created in order to suit the most common used tensile test machine. The specimen was then optimized by using finite element analysis (FEA) to find the geometry and the size of the pre-notch to avoid the mixed mode loading and minimize effects of normal stresses. For the specimen in discussion, an upper and lower limit of usable ligament length can be found. A method for determining the fracture toughness was discussed according to the essential work of fracture. Finally, an example of a special application of the proposed specimen was presented where the variation of shear strength of controlled delamination material (CDM) was measured.
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| 9. |
- Islam, Md. Shafiqul, 1984-, et al.
(författare)
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The Effects of Stress Triaxiality on the Neck Initiation and Fracture of High-density Polyethylene (HDPE)
- 2022
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Ingår i: Procedia Structural Integrity. - : Elsevier. - 9781713870302 ; , s. 745-754
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Konferensbidrag (refereegranskat)abstract
- This study analyses the tensile mechanical behaviour and deformation of neck i.e localization initiation, propagation and fracture of injection-moulded polymer composed of high-density polyethylene (HDPE) as a function of initial stress triaxiality. Three different specimen geometries namely i) Simple tension, ii) Plane strain and iii) Shear specimens were punched from injection-moulded HDPE plates and tested experimentally in uniaxial tension to introduce different stress triaxialities. These specimen geometries used are standard for the material characterization of sheet metals. However, for plate polymer materials such specimen geometries have not comprehensively been studied earlier. Standard shear specimen geometry has been further optimized in this work using finite element models to restrict unwanted out-of-plane deformations arising at large deformation. The digital image correlation (DIC) technique is used to acquire the full field deformation and in particular the localized strains in the neck region of the specimens. Based on the major-minor strain paths from DIC-measurements stress triaxiality has been calculated. It is challenging to follow the stochastic pattern at larger local strain in DIC and hence the strain at failure has been measured using orthogonal grid lines on the specimen surface. Finally, strains at neck-initiation and failure at three different stress triaxialities are reported for injection-moulded HDPE in two material orientations. It is observed that within the elastic limit the stress triaxialities obtained from the experimental tests were close to the ideal values found in the literature and neck-initiation strain is strongly dependent on the stress triaxiality. However, as neck initiates and propagates, the triaxialities for all geometries shift closer to the measured value in a simple tension specimen i.e. 0.33 limiting the effect of the initial triaxiality on failure strain.
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| 10. |
- Kao-Walter, Sharon, et al.
(författare)
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A Finite Element Analysis of a Crack Penetrating or Deflecting into an Interface in a Thin Laminate
- 2006
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Ingår i: Key Engineering Materials. - Switzerland : Trans. Tech. Publications. - 1013-9826 .- 1662-9795. ; 312, s. 173-178
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Tidskriftsartikel (refereegranskat)abstract
- The crack tip driving force of a crack growing from a pre-crack that is perpendicular to and terminating at an interface between two materials is investigated using a linear fracture mechanics theory. The analysis is performed both for a crack penetrating the interface, growing straight ahead, and for a crack deflecting into the interface. The results from finite element calculations are compared with asymptotic solutions for infinitesimally small crack extensions. The solution is found to be accurate even for fairly large amounts of crack growth. Further, by comparing the crack tip driving force of the deflected crack with that of the penetrating crack, it is shown how to control the path of the crack by choosing the adhesion of the interface relative to the material toughness.
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