On the Mechanics of Micro-Thin Foil Production

1973 ◽  
Vol 95 (3) ◽  
pp. 803-808 ◽  
Author(s):  
E. G. Thomsen ◽  
H. H. Thomsen
Keyword(s):  
Thin Foil ◽  
Large Impact ◽  
Interfacial Friction ◽  
Impact Loads ◽  
Metal Foil ◽  
Poisson Effect ◽  
Compression Process ◽  
Leaf Production ◽  
Actual Mechanism ◽  
Stretching Process

The mechanics of micro-thin foil or leaf production by hammering has been analyzed. It was found that the metal foil cannot be reduced by a compression process alone because of the large impact loads that would be required, due to interfacial friction between the foil and the separating paper sheets. It is demonstrated that a likely mechanism is a plastic stretching process of the metal combined with relatively large elastic stretching of the paper due to the Poisson effect when a blow is struck. The actual mechanism is probably a combination of stretching and slipping of the metal.

Investigating X-Ray Bragg-Line Displacement as a Technique for Determination of the Thermal Expansion Coefficient of Solid Samples

2004 ◽  
Vol 443-444 ◽  
pp. 151-154 ◽  
Author(s):  
S. Battaglia ◽  
F. Mango
Keyword(s):  
Thermal Expansion ◽  
Thin Foil ◽  
Bulk Sample ◽  
Peak Position ◽  
Metal Foil ◽  
Joule Effect ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Wire Coil ◽  
Heat Dispersion

Thermal expansion coefficients (TEC) of some metallic samples and rocks, along with one sample of amorphous silica, were determined by means of a standard X-ray diffractometer without any modification to the equipment. Only the sample holder was modified in order to fix the sample within the standard goniometer and avoid heat dispersion into the chamber during heating of the sample. The latter was achieved by the Joule effect through a thermo-coaxial wire coil wrapped directly around the bulk sample. A thin metal foil, aluminium in our case, was placed on the flat surface of the cylinder sample. The variations in Al peak position recorded at various sample temperatures were related directly to the dilatation of the material supporting the thin foil.

A Direct Design Procedure for FPSO Side Structures Against Large Impact Loads

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Lin Hong ◽  
Jørgen Amdahl ◽  
Ge Wang
Keyword(s):  
Heavy Traffic ◽  
Limit State ◽  
Design Procedure ◽  
Large Impact ◽  
Collapse Mechanism ◽  
Impact Loads ◽  
Element Analysis ◽  
Direct Design ◽  
Offshore Industry ◽  
The Impact

The performance and consequence of FPSOs subjected to large impact loads such as collisions from supply vessels or merchant vessels are of great concern in the offshore industry, notably when they are located close to heavy traffic lanes. Due to the lack of operation experience for ship-shaped FPSOs, direct design procedures are needed to rationalize the structural design of FPSOs, which can mitigate the consequence of collision accident and avoid possible contaminated compartment flooding. In this paper, three collision scenarios between a FPSO and a bulbous supply vessel are analyzed through explicit nonlinear finite element analysis code LS-DYNA. Thereafter, a direct design procedure is proposed for ship-shaped FPSO side structure against accidental collision forces, which follows the principle of accidental limit state. The procedure comprises the determination of the impact forces, shell plating, and stiffener framing design, and the consideration of the acceptance criterion. The proposed method is especially useful in the preliminary design phase because the design procedure for plating and stiffener is based on analytical formulas derived from plastic method and appropriate collapse mechanism. The side structure decided by the proposed design procedure also complies with the strength design principle that has been adopted in NORSOK standard. The proposed approach is demonstrated by the design of the FPSO side structure against impact loads from a 7500 tons supply vessel and verified by means of integrated collision analysis. The procedure could also be served to estimate the damage due to accidental loads.

Determination of Forming Limit Diagrams for Thin Foil Materials Based on Scaled Nakajima Test

2015 ◽  
Vol 794 ◽  
pp. 190-198 ◽  
Author(s):  
Stefan Veenaas ◽  
Gerrit Behrens ◽  
Konstantin Kröger ◽  
Frank Vollertsen
Keyword(s):  
Stress State ◽  
Deep Drawing ◽  
Axial Stress ◽  
Forming Limit Diagram ◽  
Thin Foil ◽  
Chromium Steel ◽  
Forming Limit ◽  
Metal Foil ◽  
Forming Limit Diagrams ◽  
Process Understanding

For a better process understanding of micro deep drawing processes and reliable prediction of component failure in FE simulations, it requires the most accurate knowledge of actual material behaviour. However, it is not sufficient to describe material failure for a multi axial stress state in deep drawing using a mechanical parameter as the elongation from tensile test. A forming limit diagram and a forming limit curve are more suited to describe the limit of formability under deep drawing stress state conditions. Methods like hydraulic or pneumatic bulge tests are available to determine forming limit curves even for thin metal foil materials. Nevertheless, using these methods only positive minor strains can be achieved. Especially for a deep drawing process negative minor strains and the left side of a forming limit diagram are more important. Therefore, in this study, experiments based on scaled Nakazima tests were performed to determine complete forming limit diagrams for different foil materials with a thickness range of 20 µm to 25 µm. Scaling the test setup improves the handling of thin specimens. Results with a higher local resolution and the specimens’ size is much closer to the actual size of a micro deep drawn component. Using this testing method forming limit diagrams for the materials Al99.5, E-Cu58, stainless austenitic nickel-chromium steel X5CrNi18-10 (1.4301 / AISI 304), all produced by rolling, and an Al-Zr-foil, produced by a PVD sputtering process, were determined for the micro range.

Recent Studies on the Dynamic Plastic Behavior of Structures

1989 ◽  
Vol 42 (4) ◽  
pp. 95-115 ◽  
Author(s):  
Norman Jones
Keyword(s):  
Brittle Fracture ◽  
Dynamic Loads ◽  
Large Impact ◽  
Plastic Behavior ◽  
Impact Loads ◽  
Plastic Strains ◽  
Review Of The Literature ◽  
Rigid Plastic ◽  
Plastic Buckling ◽  
Fracture Transition

This article contains a review of the literature, which has been published recently, on the dynamic plastic behavior of simple structures. The dynamic loads cause large plastic strains which dominate material elastic effects. Thus, the accuracy of various refinements of simple rigid-plastic methods are discussed, together with the phenomena of pseudoshakedown under repeated loads, dynamic plastic buckling, and dynamic progressive buckling. Recent studies are also reported on similitude under large impact loads, and on the ductile-brittle fracture transition due to the changes in the physical dimensions of a structure.

Plastic Deformation of Thin Foil Substrates with Amorphous Silicon Islands into Spherical Shapes

2000 ◽  
Vol 621 ◽  
Author(s):  
Pai-hui I. Hsu ◽  
Min Huang ◽  
Sigurd Wagner ◽  
Zhigang Suo ◽  
J. C. Sturm
Keyword(s):  
Plastic Deformation ◽  
Amorphous Silicon ◽  
Permanent Deformation ◽  
Spherical Shape ◽  
Thin Foil ◽  
Metal Foil ◽  
Large Area ◽  
Spherical Cap ◽  
Planar Substrates ◽  
Silicon Islands

ABSTRACTThere is a growing interest in the application of large area electronics on curved surfaces. One approach towards realizing this goal is to fabricate circuits on planar substrates of thin plastic or metal foil, which are subsequently deformed into arbitrary shapes. The problem that we consider here is the deformation of substrates into a spherical shape, where the strain is determined by geometry and cannot be reduced by simply using a thinner substrate. The goal is to achieve permanent, plastic deformation in the substrates, without exceeding fracture or buckling limits in the device materials.Our experiments consist of the planar fabrication of amorphous silicon device structures onto stainless steel or Kapton® polyimide substrates, followed by permanent deformation into a spherical shape. We will present empirical experiments showing the dependence of the results on the island/line size of the device materials and the deformation temperature. We have successfully deformed Kapton® polyimide substrates with 100 [.proportional]m wide amorphous silicon islands into a one steradian spherical cap, which subtends 66 degrees, without degradation of the silicon. This work demonstrates the feasibility of building semiconductor devices on plastically deformed substrates despite a 5% average biaxial strain in the substrate after deformation.

Some Recent Studies on Plastic Behavior of Plates Subjected to Large Impact Loads

2002 ◽  
Vol 124 (3) ◽  
pp. 125-131 ◽  
Author(s):  
Ge Wang
Keyword(s):  
Steel Plates ◽  
Large Impact ◽  
Plastic Behavior ◽  
Complex Object ◽  
Impact Loads ◽  
Complex Interactions ◽  
Analytical Formulas ◽  
Membrane Stretching ◽  
The Many ◽  
Deformation Patterns

This paper reviews some recent studies on the plastic behavior of steel plates subjected to large impact loads. This is an important topic for risk assessments and safety evaluations because of the ever heightened public concern about safety of marine structures and potential harm to the environment due to marine accidents. Emphasis is given to the complex plastic deformation patterns recently identified, including plate punching, plate tearing, and local denting of web girders. Descriptions are given of the complex interactions of the many mechanisms involved in these deformation patterns, including membrane stretching, local plastic bending, complex object geometry, rupture, cracking and friction. Advanced analytical formulas that can be used to describe these behavior mechanisms are introduced. These formulas are based on the advanced structural crashworthiness methodology.

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

Electrolytic Isolation of Twin-Type Shock Deformation Structures

1967 ◽  
Vol 25 ◽  
pp. 318-319
Author(s):  
F. I. Grace ◽  
L. E. Murr
Keyword(s):  
Grain Boundaries ◽  
Thin Foil ◽  
Electrolyte Composition ◽  
Experimental Conditions ◽  
Average Current Density ◽  
Electron Transmission ◽  
Deformation Structures ◽  
The Matrix ◽  
Average Current ◽  
Specimen Edge

During the course of electron transmission investigations of the deformation structures associated with shock-loaded thin foil specimens of 70/30 brass, it was observed that in a number of instances preferential etching occurred along grain boundaries; and that the degree of etching appeared to depend upon the various experimental conditions prevailing during electropolishing. These included the electrolyte composition, the average current density, and the temperature in the vicinity of the specimen. In the specific case of 70/30 brass shock-loaded at pressures in the range 200-400 kilobars, the predominant mode of deformation was observed to be twin-type faults which in several cases exhibited preferential etching similar to that observed along grain boundaries. A novel feature of this particular phenomenon was that in certain cases, especially for twins located in the vicinity of the specimen edge, the etching or preferential electropolishing literally isolated these structures from the matrix.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

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