Viscoelastic Characterization of a Thermoplastic Elastomer Processed through Material Extrusion

Adrover-Monserrat, Bàrbara; García-Vilana, Silvia; Sánchez-Molina, David; Llumà, Jordi; Jerez-Mesa, Ramón; Travieso-Rodríguez, J. Antonio

doi:10.3390/polym14142914

Cited by 3 publications

(4 citation statements)

References 39 publications

(59 reference statements)

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“…Akshat Agha et al [13] utilized a dynamic thermo-mechanical analyzer to conduct shear tests on a one-component epoxy-based thermosetting adhesive to investigate viscoelasticity and plastic deformation of the material during thermal curing, developing a viscoelastic model to predict residual stresses generated in the adhesive. Bàrbara Adrover-Monserrat et al [14] determined the Prony series parameters of their viscoelastic model by conducting uniaxial relaxation tests on polyether block amide filaments, confirming the reliability of the model by rapid cyclic loading tests.…”

Section: Introductionmentioning

confidence: 87%

Characterization of Potting Epoxy Resins Performance Parameters Based on a Viscoelastic Constitutive Model

Yang,

Ding,

et al. 2024

Polymers

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To describe the evolution of residual stresses in epoxy resin during the curing process, a more detailed characterization of its viscoelastic properties is necessary. In this study, we have devised a simplified apparatus for assessing the viscoelastic properties of epoxy resin. This apparatus employs a confining cylinder to restrict the circumferential and radial deformations of the material. Following the application of load by the testing machine, the epoxy resin sample gradually reduces the gap between its surface and the inner wall of the confining cylinder, ultimately achieving full contact and establishing a continuous interface. By recording the circumferential stress–strain on the outer surface of the confining cylinder, we can deduce the variations in material bulk and shear moduli with time. This characterization spans eight temperature points surrounding the glass transition temperature, revealing the bulk and shear relaxation moduli of the epoxy resin. Throughout the experiments, the epoxy resin’s viscoelastic response demonstrated a pronounced time-temperature dependency. Below the glass transition temperature, the stress relaxation response progressively accelerated with increasing temperature, while beyond the glass transition temperature, the stress relaxation time underwent a substantial reduction. By applying the time-temperature superposition principle, it is possible to construct the relaxation master curves for the bulk and shear moduli of the epoxy resin. By fitting the data, we can obtain expressions for the constitutive model describing the viscoelastic behavior of the epoxy resin. In order to validate the reliability of the test results, a uniaxial tensile relaxation test was conducted on the epoxy resin casting body. The results show good agreement between the obtained uniaxial relaxation modulus curves and those derived from the bulk and shear relaxation modulus equations, confirming the validity of both the device design and the testing methodology.

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Section: Introductionmentioning

confidence: 87%

Characterization of Potting Epoxy Resins Performance Parameters Based on a Viscoelastic Constitutive Model

Yang,

Ding,

et al. 2024

Polymers

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“…It is common to model viscoelastic media as a combination of springs and dashpots for examples the Maxwell–Wiechert model show in Figure 3 . The frequency domain response of the system in Figure 3 can be expressed as:

where

is the complex modulus and

is the angular frequency, and

is the relaxation time [ 50 , 51 ]. For the case of a network with just three components,

and

, the model reduces to what is referred to the SLS model or Zener model [ 28 , 52 ].…”

Section: Methodsmentioning

confidence: 99%

“…where G * (ω) is the complex modulus and ω is the angular frequency, and τ k = η k /G k is the relaxation time [50,51]. For the case of a network with just three components, G ∞ , G 1 and η 1 , the model reduces to what is referred to the SLS model or Zener model [28,52].…”

Section: Viscoelasticitymentioning

confidence: 99%

Biomechanical Modelling of Porcine Kidney

Mishra,

Cleveland

2024

Bioengineering

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In this study, the viscoelastic properties of porcine kidney in the upper, middle and lower poles were investigated using oscillatory shear tests. The viscoelastic properties were extracted in the form of the storage modulus and loss modulus in the frequency and time domain. Measurements were taken as a function of frequency from 0.1 Hz to 6.5 Hz at a shear strain amplitude of 0.01 and as function of strain amplitude from 0.001 to 0.1 at a frequency of 1 Hz. Measurements were also taken in the time domain in response to a step shear strain. Both the frequency and time domain data were fitted to a conventional Standard Linear Solid (SLS) model and a semi-fractional Kelvin–Voigt (SFKV) model with a comparable number of parameters. The SFKV model fitted the frequency and time domain data with a correlation coefficient of 0.99. Although the SLS model well fitted the time domain data and the storage modulus data in the frequency domain, it was not able to capture the variation in loss modulus with frequency with a correlation coefficient of 0.53. A five parameter Maxwell–Wiechert model was able to capture the frequency dependence in storage modulus and loss modulus better than the SLS model with a correlation of 0.85.

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“…In the framework of biomechanical applications, the AE technique has been used to analyze the fracture of bone and other biological materials; however, there are few quantitative models which use AE data for the prediction of fracture [27,29,28,30]. The novel part of this work lies in the stochastic model presented in section 2.2, whose application to experimental data is discussed in section 3.…”

Section: Introductionmentioning

confidence: 99%

Acoustic emission applied to stochastic modeling of microdamage in compact bone

Sanchez-Molina,

García-Vilana

2024

Preprint

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Exploring the stochastic intricacies of bone microstructure is a promising way to make progress on the practical issue of bone fracture. This study investigates the fracture of human complete ribs subjected to bending and using Acoustic Emission (AE) for microfailure detection. As the strain increases, the number of AE signals per unit of time rises until, beyond a certain threshold, an avalanche of signals occurs, indicating the aggregation of numerous microfailures into a macroscopic fracture. Since microfailures appear randomly throughout the bending test, and given the lack of a deterministic law and the random nature of microfailures during the bending test, we opted to develop a stochastic model to account for their occurrence within the irregular and random microstructure of the cortical bone. Notable discoveries encompass the significant correlation between adjusted parameters of the stochastic model and the total number of microfailures with anthropometric variables such as age and body mass index (BMI). The progression of microfailures with strain is significantly more pronounced with age and BMI, as measured by the rate of bone deterioration. In addition, the rate of microfailures is significantly impacted by BMI alone. It is also observed that the average energy of the identified AE events adheres to a precisely defined Pareto distribution for every specimen, with the principal exponent exhibiting a significant correlation with anthropometric variables. From a mathematical standpoint, the model can be described as a double Cox stochastic and explosive (coxplosive process) model. This further provides insight into the reason why the ribs of older individuals are considerably less resilient than those of younger individuals, breaking under a considerably lower maximum strain εmax).

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Viscoelastic Characterization of a Thermoplastic Elastomer Processed through Material Extrusion

Cited by 3 publications

References 39 publications

Characterization of Potting Epoxy Resins Performance Parameters Based on a Viscoelastic Constitutive Model

Characterization of Potting Epoxy Resins Performance Parameters Based on a Viscoelastic Constitutive Model

Biomechanical Modelling of Porcine Kidney

Acoustic emission applied to stochastic modeling of microdamage in compact bone

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