Modeling Nanoscale Rheological and Mechanical Properties of Thin Film Asphalt Binder

2016 ◽  
Author(s):  
Hasan M. Faisal ◽  
Zafrul Hakim Khan ◽  
Rafiqul Tarefder
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Test Data ◽  
Asphalt Concrete ◽  
Asphalt Binder ◽  
Nanoindentation Test ◽  
Film Material ◽  
Macro Scale ◽  
Sdr Model

Traditionally, mechanical properties of asphalt concrete (AC) is evaluated through macro-scale testing. However, when aggregates are mixed with asphalt binder, it creates a thin film of 20μm to 40μm around the aggregate particles and the primary strength of AC is derived from the interaction between the binder and aggregates. Therefore, to understand the behavior of asphalt concrete it is necessary to study the binder properties in a nanoscale. Nanoindentation test has been adopted to examine the thin film material property. In a nanoindentation test, a loaded nanoindenter is used to indent the sample surface and measure the indenter displacement as a function of load. To this day, most researchers have used the Oliver-Pharr method to analyze the indentation test data and obtain Elastic modulus (E) and hardness (H) of the material. Generally, in a nanoindentation test, there is a loading and unloading phase. In an elasto-plastic material, loading phase has elastic and plastic response and unloading phase has only elastic response. In Oliver-Pharr method, elastic modulus is obtained through the slope of the unloading curve. Therefore, Oliver-Pharr method mostly applicable for the elasto-plastic metals because it does not incorporate any viscous effect. However, in case of visco-elastic material like asphalt, during the unloading phase, the slope of the unloading curve becomes negative due to the viscous flow. Therefore, using Oliver-Pharr (OP) method in this circumstances will yield an inaccurate value of modulus of elasticity. In the current study, the test data was modeled and analyzed using a well-established spring-dashpot-rigid (SDR) model for viscoelastic material to determine the elastic, plastic and viscous properties. The model assumes the indenter displacement is a function of a quadratic spring, a quadratic dashpot and a plastic rigid body. The loading phase of the nanoindentation test has three contributing parameters: elasticity (E), indentation viscosity (η) and hardness (H). During creep, only contributing parameter is indentation viscosity (η) and while unloading the contributing factors are found to be E and η. Nonlinear least square curve fitting technique was employed to model the nanoindentation test data to the SDR model to find out the contributing parameters E, η and H. In addition, the extended dwell time on the asphalt binder samples produced positive load displacement curves, which were further analyzed with Oliver-Pharr method. Comparison between two models results show traditional Oliver-Pharr model predicts the material properties 5 to 10 times lower than SDR model, as Oliver-Pharr does not consider the viscous behavior in the material.

Nano-Scale Binder Phase Identification in Asphalt Concrete

2017 ◽  
Author(s):  
Hasan M. Faisal ◽  
Zafrul Hakim Khan ◽  
Rafiqul Tarefder
Keyword(s):  
Asphalt Concrete ◽  
Coarse Aggregate ◽  
Asphalt Binder ◽  
Nanoindentation Test ◽  
Phase Identification ◽  
Binder Phase ◽  
Depth Range ◽  
Creep Response ◽  
Macro Scale ◽  
Asphalt Film

Asphalt concrete (AC) consists of asphalt binder and aggregate. Aggregate consists of: coarse aggregate and fines. Asphalt binder creates a coating or film around the aggregate, which is defined as the binder phase of AC. Fines are believed to be trapped inside an asphalt film or mixed with asphalt binder, creating a composite material called mastic. Thus, AC has three phases: mastic, asphalt film binder, and coarse aggregate. All these phases play major roles in performance of AC. Researchers have performed various tests on asphalt binder at micro scale to understand the macro scale behavior of AC. However, test methods developed and performed on binders, to this day, are mostly rheological shear and bending beam tests. No studies have been conducted on the compression stiffness or modulus and hardness of and binder, rather than shear and binders stiffness. In addition, the existing tests used in the asphalt area cannot be performed on binder and mastic while they are an integral part of AC. Nanoindentation tests can be performed on aggregate and asphalt binder while they are integral parts of AC. Because, in nanoindentation test, a nanometer size tip, which is smaller than binder film thickness as well as other phases. In the study, Performance Grade (PG) 64–28 was used for the study, same binder had been used afterwards to characterize asphalt and AC. A loading rate of 0.005 mN/sec, a dwell time of 200 sec and a maximum load 0.055 mN were employed in the study. In the current study 20 indentations were done on the asphalt binder sample and 100 indentations were done on AC sample, due to heterogeneity of the sample. However, to identify a specific phase in AC sample, the current study adopts the depth range technique for as same loading protocol. The depth rage of binder phase was acquired by independent indentation on same asphalt binder sample. As, asphalt is known to be a viscoelastic material that exhibits creep behavior, the creep compliance of asphalt binder was used for validation of the depth range assumption. The validation of phase identification was done by comparing the asphalt binder phase creep response while they are integral part of AC with creep response of independent asphalt binder sample under nanoindenter. The comparison shows depth resolution technique can successfully identify the binder phase of AC.

scholarly journals Evaluation Method of Granite Multiscale Mechanical Properties Based on Nanoindentation Technology

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Man Lei ◽  
Fa-ning Dang ◽  
Haibin Xue ◽  
Mingming He
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Uniaxial Compression ◽  
Compression Test ◽  
Evaluation Method ◽  
Poisson Ratio ◽  
Nanoindentation Test ◽  
Uniaxial Compression Test ◽  
Displacement Curve ◽  
Mineral Contents

In order to study the mechanical properties of granite at the micro- and nanoscale, the load-displacement curve, residual indentation information, and component information of the quartz, feldspar, and mica in granite were obtained using a nanoindentation test, a scanning electron microscope (SEM), and X-ray diffraction (XRD). The elastic modulus and the hardness of each component of the granite were obtained through statistical analysis. Treating rock as a composite material, the relation between the macro- and microscopic mechanical properties of rock was established through the theory of micromechanical homogenization. The transition from micromechanical parameters to macromechanical parameters was realized. The equivalent elastic modulus and Poisson’s ratio of the granite were obtained by the Self-consistent method, the Dilute method, and the Mori-Tanaka method. Compared with the elastic modulus and the Poisson ratio of granites measured by a uniaxial compression test and the available data, the applicability of the three methods were analyzed. The results show that the elastic modulus and hardness of the quartz in the granite is the largest, the feldspar is the second, the mica is the smallest. The main mineral contents in granite were analyzed using the semiquantitative method by XRD and the rock slice identification test. The elastic modulus and the Poisson ratio of granite calculated by three linear homogenization methods are consistent with those of the uniaxial compression test. After comparing the calculation results of the three methods, it is found that the Mori-Tanaka method is more suitable for studying the mechanical properties of rock materials. This method has an important theoretical significance and practical value for studying the quantitative relationship between macro- and micromechanical indexes of brittle materials. The research results provide a new method and an important reference for studying the macro-, micro-, and nanomechanical properties of rock.

Optimization of mechanical properties of thin free-standing metal films for RF-MEMS

2004 ◽  
Vol 820 ◽  
Author(s):  
Jaap M.J. den Toonder ◽  
Auke R. van Dijken
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Yield Strength ◽  
Rf Mems ◽  
High Yield ◽  
Film Material ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Aluminum Films ◽  
Materials Used

AbstractThe mechanical properties of the thin film materials used in RF-MEMS are crucial for the reliability and proper functioning of the devices. In this paper we study a large number of aluminum alloys as possible RF-MEMS thin film materials. The yield strength and creep properties are measured using nano-indentation. The results show that the mechanical properties of thin aluminum films can be improved substantially by alloying elements. Of the alloys studied in this paper, AlCuMgMn in particular seems quite promising as a thin film material for RF MEMS, having both high yield strength and little creep. Using X-ray diffraction and electron microscopy, the observed effects are partly explained.

Mechanical properties and creep behavior of lyocell fibers by nanoindentation and nano-tensile testing

Holzforschung ◽  
2007 ◽  
Vol 61 (3) ◽  
pp. 254-260 ◽  
Author(s):  
Seung-Hwan Lee ◽  
Siqun Wang ◽  
George M. Pharr ◽  
Matthew Kant ◽  
Dayakar Penumadu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Tensile Testing ◽  
Holding Time ◽  
Time Dependent ◽  
Nanoindentation Test ◽  
Creep Equation ◽  
Mean Values ◽  
Significant Difference ◽  
Lyocell Fibers

Abstract Mechanical and time-dependent mechanical properties of lyocell fibers have been investigated as a function of depth at a nano-scale level in longitudinal and transverse directions. The nanoindentation technique was applied and extended to continuous stiffness measurement. Lyo10 and Lyo13 lyocell fibers were investigated. The individual fiber properties were measured using a nano-tensile testing system to obtain reference data for mechanical properties. The hardness and elastic modulus obtained from nanoindentation test are described using two different approaches. The first uses mean values for a depth of 150–300 nm, while the second uses unloading values at the final indentation depth. There is no significant difference between modulus values inferred from nanoindentation and those obtained from single fiber tensile testing. Hardness and elastic modulus values were higher in the longitudinal direction than those in the transverse direction and Lyo13 values were higher than those for Lyo10 in both directions. The time-dependent mechanical properties were also investigated as a function of the holding time. Increasing the holding time led to an increase in indentation displacement and a decrease in hardness. Stress exponents were calculated from the linear relationship between contact stress and contact strain using a power-law creep equation.

scholarly journals A Direct Comparison of Three Buckling-Based Methods to Measure the Elastic Modulus of Nanobiocomposite Thin Films

2020 ◽  
Author(s):  
Taylor C. Stimpson ◽  
Daniel A. Osorio ◽  
Emily D. Cranston ◽  
Jose Moran-Mirabal
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elastic Moduli ◽  
Input Parameter ◽  
Layer By Layer ◽  
Free Standing ◽  
Film Composition ◽  
Parameter Values

<p>To engineer tunable thin film materials, accurate measurement of their mechanical properties is crucial. However, characterizing the elastic modulus with current methods is particularly challenging for sub-micrometer thick films and hygroscopic materials because they are highly sensitive to environmental conditions and most methods require free-standing films which are difficult to prepare. In this work, we directly compared three buckling-based methods to determine the elastic moduli of supported thin films: 1) biaxial thermal shrinking, 2) uniaxial thermal shrinking, and 3) the mechanically compressed, strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) method. Nanobiocomposite model films composed of cellulose nanocrystals (CNCs) and polyethyleneimine (PEI) were assembled using layer-by-layer deposition to control composition and thickness. The three buckling-based methods yielded the same trends and comparable values for the elastic moduli of each CNC-PEI film composition (ranging from 15 – 44 GPa, depending on film composition). This suggests that the methods are similarly effective for the quantification of thin film mechanical properties. Increasing the CNC content in the films statistically increased the modulus, however, increasing the PEI content did not lead to significant changes. The standard deviation of elastic moduli determined from SIEBIMM was 2-4 times larger than for thermal shrinking, likely due to extensive cracking and partial film delamination. In light of these results, biaxial thermal shrinking is recommended as the method of choice because it affords the simplest implementation and analysis and is the least sensitive to small deviations in the input parameter values, such as film thickness or substrate modulus.</p>

Mechanical Properties of Ion-Irradiated Stainless Steel Determined by Nanoindentation Tests and Finite Element Analyses

2020 ◽  
Author(s):  
Jae Min Sim ◽  
Yoon-Suk Chang ◽  
Byeong Seo Kong ◽  
Changheui Jang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Test Data ◽  
Radiation Effects ◽  
Ion Irradiation ◽  
Nanoindentation Test ◽  
Finite Element Analyses ◽  
Stress Strain ◽  
Term Operation ◽  
Constitutive Parameters

Abstract While austenitic stainless steels (ASSs) have been widely adopted for reactor vessel internals because of their excellent material properties, diverse ageing-related degradation may occur due to high temperature, corrosive and neutron radiation environments during operation. In particular, since the change of mechanical properties is a major concern in long-term operation but it is difficult to prepare and handle standard specimens influenced by neutrons, most of experimental researches for enhanced understanding of the radiation effects have been focused on high-energetic ion-irradiation and tests of small specimens. In this study, systematic finite element analyses were carried out to quantify changing mechanical properties based on both virgin and ion-irradiated nanoindentation test data of typical ASS material. First of all, numerical analysis was carried out to obtain unirradiated material constitutive parameters by using trial set along the miniature specimen and comparing test data, and then indentation stress-strain (ISS) curve was derived. Subsequently, ISS was converted into uniaxial stress-strain response taking into account simple correlation. Finally, with regard to the irradiated material, similar analytical procedures were established. 304 SS was irradiated with 2 MeV proton and radioactivity is being measured. Comparison between analysis result and experimental one will be carried out, of which details and key findings will be discussed.

Film Stress in High Density Thin Film Interconnect

1989 ◽  
Vol 154 ◽  
Author(s):  
J. Tony Pan ◽  
Steve Poon
Keyword(s):  
Thin Film ◽  
Elastic Modulus ◽  
High Speed ◽  
High Density ◽  
Film Stress ◽  
Processing Temperature ◽  
Copper Films ◽  
Film Material ◽  
Repeated Heating ◽  
Heating And Cooling

AbstractHigh density thin film interconnects are expected to be widely used for multi-chip module application to accommodate next generation high I/O and high speed integrated circuits. These interconnects typically use polyimide as the dielectric, and aluminum or copper (with protective overcoat) as the conductor. The interconnects are typically built on silicon or alumina substrates. Large film stress occurs due to the high processing temperature required to cure polyimide and due to the mismatch in thermal coefficients of expansion (TCE) between the film materials and substrate materials. This work studies film stress for these materials.An instrument which measures thin film stress in-situ at temperatures between 25 and 450°C was used to characterize the stress in polyimide, nickel, and copper films. Two substrate materials, silicon and sapphire, were used in order to extract the TCE and elastic modulus for each film material. Three polyimide materials were evaluated. One of the polyimides studied showed complete stress relaxation at temperatures above 300°C and was almost completely elastic upon heating and cooling between 25 and 300°C. The TCE was calculated to be 41×10−6/°C and the biaxial elastic modulus was 4.0×109 Pascal. The nickel had very low stress asplated, however, high tensile stress was observed after 350°C annealing as a result of TCE mismatch. After first annealing, the nickel was almost completely elastic upon cooling and repeated heating and cooling between 25 and 350°C. Copper, on the other hand, was not completely elastic under similar thermal treatments. High thermal stress caused plastic deformation to occur in copper films. The room temperature stress in copper film after 350°C annealing depended on yield strength instead of TCE mismatch. The stress in these materials and its effects on processing and reliability for high density interconnect will be reported.

scholarly journals Structure and Tribo-Mechanical Properties of MoSx:N:Mo Thin Films Synthesized by Reactive dcMS/HiPIMS

2021 ◽  
Author(s):  
Wolfgang Tillmann ◽  
Alexandra Wittig ◽  
Dominic Stangier ◽  
Carl-Arne Thomann ◽  
Jörg Debus ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Solid Lubricant ◽  
Tribological Behavior ◽  
Sliding Contact ◽  
High Wear Resistance ◽  
Film Material ◽  
Low Friction ◽  
Property Profile

AbstractModifying MoS2 thin films by additional elements shows great potential in order to adjust the property profile and to meet the increasing requirements regarding high wear resistance and low friction properties of industrial components. Within that context, MoSx:N:Mo thin films were deposited by a reactive hybrid dcMS/HiPIMS process. By systematically increasing the Mo target cathode power, an investigation of the structural and the mechanical properties was conducted to understand the evolution of the tribological behavior. A low Mo target cathode power of 1 kW is related to the formation of the preferential (002) MoS2 basal-plane and thus a low friction with µ = 0.2. With an increasing amount of Mo, the film loses its solid lubricant MoS2 properties and a nitride constitution of the thin film is developing due to the formation of crystalline Mo and MoN phases. Related to this transformation, the hardness and elastic modulus are increased, but the adhesion and the tribological properties are impaired. The film loses its plasticity and the generated film material is directly removed from the contact area during the sliding contact.

scholarly journals Study on mechanical properties of granite minerals based on nanoindentation test technology

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4457-4463
Author(s):  
Man Lei ◽  
Fa-Ning Dang ◽  
Hai-Bin Xue ◽  
Zhang Yu ◽  
Ming-Ming He
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Mineral Composition ◽  
Energy Analysis ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Analysis Method ◽  
Test Technology

In this paper, the nanoscale mechanical properties of quartz, feldspar, and mica in granite are studied by the nanoindentation technique. Firstly, the surface morphol?ogy of each mineral composition in granite is obtained by a SEM. Secondly, the elastic modulus and hardness of three minerals in granite are calculated through the load-displacement curve obtained by the nanoindentation test. Based on the energy analysis method, the nanometer fracture toughness of three minerals in granite is obtained. Finally, the correlation between the elastic modulus, the hard?ness, and the fracture toughness are obtained by experimental data.

Fracture Toughness Measurement of Asphalt Concrete by Nanoindentation

2017 ◽  
Author(s):  
Zafrul Khan ◽  
Hasan M. Faisal ◽  
Rafiqul Tarefder
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Release Rate ◽  
Asphalt Concrete ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Macro Scale ◽  
Load Displacement

Fracture toughness and fracture energy release rate are two important parameters to understand the crack propagation within any material. Fracture toughness of asphalt concrete (AC) is vital to explain the fatigue cracking and low temperature cracking of asphalt pavement. These two types of distresses are still unsolved issues for asphalt researchers. Measuring fracture toughness of AC is not a new phenomenon. Recently, researchers have used several techniques to measure the fracture toughness of AC. Tests like semi-circular bending (SCB) and disk-shaped compact specimen (DCT) testing have been used to measure the fracture toughness of the AC. From the SCB or DCT tests, past researchers have shown that crack in AC propagates through mainly binder and mastic phase. All these conventional tests are carried out in macro scale. It is important to understand that before propagation of these macro scale cracks, the cracks initiates at the nano/micro scale level. With the increment of the loads these nanoscale cracks become macro scale cracks and propagates through the sample. Therefore, it is important to understand the cracks at nanoscale. In this study, nanoindentation test was introduced to measure the fracture toughness of the asphalt concrete. In a nanoindentation test, the sample surface is indented with a loaded indenter. For this test, Berkovich indenter with load control method was used. A field cored asphalt concrete sample was used for this study. The sample was collected by coring at interstate 40 (I-40) near Albuquerque, New Mexico. The sample was field aged for four years. The maximum load applied in this study was 5-mn and the unloading was done at a faster rate than the loading rate. From the load-displacement curves of the nanoindentation tests, fracture toughness of the samples was measured. The unloading curve of the nanoindentation test was further used to obtain reduced modulus of the asphalt concrete using Oliver-Pharr method. In this study, fracture energy is thought of as a portion of irreversible energy. This irreversible energy is comprised of plastic energy and energy required for propagation of crack. By analyzing the load displacement curve along with the maximum indentation depth, energy release rate and mode I fracture toughness of asphalt concrete was measured.

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