Rheological characterization of non-Brownian suspensions based on structure kinetics

Vachaparambil, Kurian J.; Mårtensson, Gustaf; Essén, Lars

doi:10.1108/ssmt-08-2017-0021

Cited by 13 publications

(5 citation statements)

References 28 publications

(40 reference statements)

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“…This material model approaches the apparent viscosity with a relatively high error at lower shear rates, which can have effect also on the results of modelling stencil printing. Contrary to this, the other widely used model, the Carreau-Yasuda model can have high errors at higher shear rates, as can be seen in the results of the work by Vachaparambil et al (2018), and as also illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 88%

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Non-Newtonian numerical modelling of solder paste viscosity measurement

Al-Ma'aiteh

Krammer

2019

SSMT

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Purpose The purpose of this paper is to present the establishment of a computational fluid dynamics model for investigating different non-Newtonian rheological models of solder pastes by simulating solder paste viscosity measurement. A combined material model was established which can follow the measured, apparent viscosity values with lower error. Design/methodology/approach The model included a parallel plate arrangement of rheometers. The diameter of the plate was 50 mm, whereas the gap between the plates was 0.5 mm. Only one quarter of the plate was modelled to enable using fine enough mesh, while keeping the calculation time low. Non-Newtonian properties were set using user defined function in Ansys, based on the Cross and Carreau–Yasuda material models. The viscosity values predicted by the mathematical models were compared to measured viscosity values of different types of solder pastes. Findings It was found that the Cross model predicts the apparent viscosity with a relatively high error (even approximately 50 per cent) at lower shear rates, whereas the Carerau–Yasuda model has higher errors at higher shear rates. The application of the proposed, combined model can result in a much lower error in the apparent viscosity between the calculated and measured viscosity values. Originality/value The error of Cross and Carreau–Yasuda material models has not been investigated yet in details. The proposed, combined material model can be applied for subsequent simulations via the described UDF, e.g. in the numerical modelling of the stencil printing. This can result in a more accurate modelling of the stencil printing process, which is inevitable considering the printing of solder paste for today fine-pitch, small size components.

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Section: Introductionmentioning

confidence: 88%

“…Many research works discussed the parameters of the stencil printing process, and also the effect of solder paste rheological properties on the stencil printing process. Vachaparambil et al (2018) developed a method for estimating the parameters of material models for thixotropic suspensions. Amalu et al…”

Section: Introductionmentioning

confidence: 99%

Non-Newtonian numerical modelling of solder paste viscosity measurement

Al-Ma'aiteh

Krammer

2019

SSMT

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“…where C 0 , C 1 , and D are all calculating parameters. According to the results of Vachaparambil [43], K 1 and K 2 can be approximated as:…”

Section: The Rheological Behaviormentioning

confidence: 99%

“…The second group of calculating parameters in Equation ( 23) were calibrated with the exothermic curve with external nanoclay doped with 0.25%: 𝑊 = −0.137132, 𝛽 = 2.001, 𝑈 = 1.1022, 𝜁 = 1.0001, 𝜉 = 1 (43) After inserting all the calculating parameters in Equation ( 23) and plotting cumulative heat over time, the comparison with the exothermic curve of 0.4% with Teng's work is shown in Figure 1. The calculating parameters remain unchanged during the plotting process.…”

Section: The First Exothermic Peak-calibration and Validationmentioning

confidence: 99%

Mathematical Modeling of Initial Exothermic Behavior and Thixotropic Properties in Nanoclay-Enhanced Cementitious Materials

Xiao,

Chen,

Cao

et al. 2024

Materials

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In the realm of cementitious materials, integrating nanoclay shows promise in enhancing properties relevant to additive manufacturing. This paper presents a novel mathematical model that combines simple empirical dissolution/nucleation Avrami-like kinetics with a thixotropic kinetics equation. To analyze the initial exothermic peak, two sets of the calculation parameter function are built to describe the exothermic rate as a function of time, following an exponential pattern. This allows for the prediction of the changes in cumulative heat and heat rate during hydration, considering different concentrations of nanoclay. In the rheological aspect, the relationship between shear stress, shear rate, and time is modeled as a combination of exponential dependencies. This enables the prediction of the variations in shear stress with one variable while holding the other constant (either time or shear rate). By integrating these aspects, this model effectively describes both the first exothermal peak and the rheological behavior during cement hydration with the inclusion of nanoclay. Validated against experimental results, these models demonstrate good accuracy (overall below 3% error), reliability, and applicability. The findings offer valuable insights into the thermal and rheological aspects of concrete printing, enabling informed design decisions for both scientific and industrial applications.

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“…This index increased with increasing metal content; it was more pronounced for solder pastes intended for stencil printing. Vachaparambil et al (2018) also characterised the rheological and thixotropic behaviour of solder pastes based on structure kinetics. They showed that during the idle time in stencil printing, there is a structure build-up in the solder paste, which increases its viscosity.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on the effect of solder paste rheological behaviour and printing speed on stencil printing

Krammer

Al-Ma'aiteh

Illés

et al. 2020

SSMT

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Purpose The purpose of this paper is to investigate the effect of different viscosity models (Cross and Al-Ma’aiteh) and different printing speeds on the numerical results (e.g. pressure over stencil) of a numerical model regarding stencil printing. Design/methodology/approach A finite volume model was established for describing the printing process. Two types of viscosity models for non-Newtonian fluid properties were compared. The Cross model was fitted to the measurement results in the initial state of a lead-free solder paste, and the parameters of a Al-Ma’aiteh material model were fitted in the stabilised state of the same paste. Four different printing speeds were also investigated from 20 to 200 mm/s. Findings Noteworthy differences were found in the pressure between utilising the Cross model and the Al-Ma’aiteh viscosity model. The difference in pressure reached 33-34% for both printing speeds of 20 and 70 mm/s and reached 31% and 27% for the printing speed of 120 and 200 mm/s. The variation in the difference was explained by the increase in the rates of shear by increasing printing speeds. Originality/value Parameters of viscosity model should be determined for the stabilised state of the solder paste. Neglecting the thixotropic paste nature in the modelling of printing can cause a calculation error of even approximately 30%. By using the Al-Ma’aiteh viscosity model over the stabilised state of solder pastes can provide more accurate results in the modelling of printing, which is necessary for the effective optimisation of this process, and for eliminating soldering failures in highly integrated electronic devices.

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Rheological characterization of non-Brownian suspensions based on structure kinetics

Cited by 13 publications

References 28 publications

Non-Newtonian numerical modelling of solder paste viscosity measurement

Non-Newtonian numerical modelling of solder paste viscosity measurement

Mathematical Modeling of Initial Exothermic Behavior and Thixotropic Properties in Nanoclay-Enhanced Cementitious Materials

Numerical investigation on the effect of solder paste rheological behaviour and printing speed on stencil printing

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