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Christofer Hierold - One of the best experts on this subject based on the ideXlab platform.
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long term Creep behavior of su 8 membranes application of the time stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A-physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
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Long-term Creep behavior of SU-8 membranes: Application of the time–stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A: Physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
B Schoeberle - One of the best experts on this subject based on the ideXlab platform.
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long term Creep behavior of su 8 membranes application of the time stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A-physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
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Long-term Creep behavior of SU-8 membranes: Application of the time–stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A: Physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
Michael Wendlandt - One of the best experts on this subject based on the ideXlab platform.
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long term Creep behavior of su 8 membranes application of the time stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A-physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
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Long-term Creep behavior of SU-8 membranes: Application of the time–stress superposition principle to determine the master Creep Compliance curve
Sensors and Actuators A: Physical, 2008Co-Authors: B Schoeberle, Michael Wendlandt, Christofer HieroldAbstract:Abstract We employ the concept of time–stress superposition on short-term Creep tests to determine the master Creep Compliance curve of glassy SU-8. For the determination of the Creep curves, the bulge test method is used. Rectangular membranes with a thickness of 2.25 μm, widths from 830 μm to 941 μm and a length of ≥6 mm are fabricated and measured. The chosen geometrical dimensions allow for the assumption of plane strain conditions. SU-8 exhibits rather low Creep (≤10% at t = 10 10 s) under constant equivalent stress of 13.2 MPa, where the initial value D 0 and transient component D e of the Creep Compliance are found to be 0.23 GPa −1 and 0.29 GPa −1 , respectively. The fracture strength σ f of the fully cured epoxy resin is measured to be 73.3 MPa. We report on modeling, fabrication, error analysis and experimental results.
Mugurel Turos - One of the best experts on this subject based on the ideXlab platform.
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Determination of Asphalt Mixture Creep Compliance at Low Temperatures by Using Thin Beam Specimens
Transportation Research Record, 2008Co-Authors: Adam Zofka, Mihai O. Marasteanu, Mugurel TurosAbstract:The thermal cracking (TC) module (TCMODEL) of the recently developed Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures (referred to as MEPDG) is used to predict thermally induced cracking in asphalt pavements over their service lives. The primary input to this model is the asphalt mixture Creep Compliance. The current standard test for determination of the Creep Compliance of asphalt mixtures is the indirect tensile test (IDT). This paper investigates the feasibility of using the bending beam rheometer (BBR) device to determine the low-temperature Creep Compliance of thin asphalt mixture beams (127 x 12.7 x 6.35 mm). The BBR device was used to evaluate 20 different asphalt mixtures, and the results were compared with the standard IDT results. Direct comparison of the BBR and the IDT results indicated that both methods produce slightly different Creep Compliance curves and that the relative ratio between the BBR and the IDT results varies with time and temperature. A simpl...
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Investigation of Asphalt Mixture Creep Compliance at Low Temperatures
Road Materials and Pavement Design, 2008Co-Authors: Adam Zofka, Mihai O. Marasteanu, Mugurel TurosAbstract:ABSTRACT The Creep Compliance is one of the main material characteristics used to describe low temperature behavior of the asphalt mixtures. It also serves as a primary input to the current thermal cracking model in the US that is used to predict thermally induced cracking in asphalt pavements over their service life. The current standard method in the US to determine Creep Compliance of asphalt mixtures is the Indirect Tensile (IDT) test. This paper investigates the feasibility of using the Bending Beam Rheometer (BBR) device to determine the low-temperature Creep Compliance of thin asphalt mixture beams (127x12.7x6.35mm). The BBR was used to evaluate 20 different asphalt mixtures and the results were compared with the standard IDT results. Direct comparison of the BBR and the IDT results indicate that both methods produce slightly different Creep Compliance curves and the relative ratio between the BBR and the IDT results varies with time and temperature. A simple phenomenological relation was proposed ...
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Investigation of asphalt Creep Compliance at low temperatures using thin beam specimens
2008Co-Authors: Adam Zofka, Mihai O. Marasteanu, Mugurel TurosAbstract:As a result of severe temperature drops in the northern USA and Canada transverse cracks develop at almost regular intervals that decrease ride quality and allow water to infiltrate and further damage the pavement. The current AASHTO specification is based on Indirect Tension (IDT) tests performed on relatively thick cylindrical specimens that limit the use of this test with field cores from thin layers or construction lifts. Furthermore, thick specimens do not enable the investigation of the gradual aging that occurs in asphalt layers as a result of oxidation and volatilization. The use of the Bending Beam Rheometer (BBR), as part of the bitumen PG system, was investigated with thin asphalt beams to determine the low-temperature Creep Compliance of the asphalts. Twenty different asphalts were tested at three temperature levels using both the IDT and the BBR instruments. Gyratory specimens were first cut into IDT specimen. The specimens were tested in the IDT and then thin beams were cut using a tile saw and were tested in the BBR. The analysis of the experimental results indicates that testing thin asphalt beams can be used for low-temperature characterization but several factors need closer investigation. For the covering abstract see ITRD E157233
Krystyn J. Van Vliet - One of the best experts on this subject based on the ideXlab platform.
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Quantifying plasticity-independent Creep Compliance and relaxation of viscoelastoplastic materials under contact loading
Journal of Materials Research, 2011Co-Authors: Matthieu Vandamme, Catherine A. Tweedie, Georgios Constantinides, Franz-josef Ulm, Krystyn J. Van VlietAbstract:Here we quantify the time-dependent mechanical properties of a linear viscoelastoplastic material under contact loading. For contact load relaxation, we showed that the relaxation modulus can be measured independently of concurrent plasticity exhibited during the loading phase. For indentation Creep, we showed that the rate of change of the contact Creep Compliance $$\dot L(t)$$ can be measured independently of any plastic deformation exhibited during loading through $$\dot L(t) = 2a(t)\dot h(t)/P_{\max } $$ , where a(t) is the contact radius, h(t) is the displacement of the contact probe, and Pmax is the constant applied load during the Creep phase. These analytical relations were compared with numerical simulations of conical indentation Creep for a viscoelastoplastic material and validated against sharp indentation Creep experiments conducted on polystyrene. The derived relations enable extraction of viscoelastic material characteristics, even if sharp probes confer concurrent plasticity, applicable for a general axisymmetric contact probe geometry and a general time-independent plasticity.
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Contact Creep Compliance of viscoelastic materials via nanoindentation
Journal of Materials Research, 2006Co-Authors: Catherine A. Tweedie, Krystyn J. Van VlietAbstract:The Creep Compliance of viscoelastic materials such as synthetic polymers is an established metric of the rate at which strain increases for a constant applied stress and can, in principle, be implemented at the nanoscale to compare quantitatively bulk or thin film polymers of different structures or processing histories. Here, we outline the evolution of contact Creep Compliance analysis and application for both conical and spherical indenter geometries. Through systematic experiments on four amorphous (glassy) polymers, two semi-crystalline polymers and two epoxies, we show that assumptions of linear viscoelasticity are not maintained for any of these polymers when Creep Compliance is measured via conical indentation at the nanoscale, regardless of the rate of stress application (step or ramp). Further, we show that these assumptions can be maintained to evaluate the contact Creep Compliance J c ( t ) of these bulk polymers, regardless of the rate of stress application, provided that the contact strains are reduced sufficiently through spherical indentation. Finally, we consider the structural and physical properties of these polymers in relation to J c ( t ), and demonstrate that J c ( t ) correlates positively with molecular weight between entanglements or crosslinks of bulk, glassy polymers.