Rate Dependence and Short-Term Creep Behavior of a Thermoset Polymer at Elevated Temperature

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
C. M. Falcone ◽  
M. B. Ruggles-Wrenn
Keyword(s):  
Creep Behavior ◽  
Viscoelastic Model ◽  
Rate Sensitivity ◽  
Monotonic Loading ◽  
Stress Rate ◽  
Creep Tests ◽  
Strain Behavior ◽  
Thermoset Polymer ◽  
Term Creep ◽  
Prior Stress

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 288°C. The effect of loading rate on monotonic stress-strain behavior as well as the effect of prior stress rate on creep behavior were explored. Positive nonlinear rate sensitivity was observed in monotonic loading. Creep response was found to be significantly influenced by prior stress rate. The effect of loading history on creep was studied in stepwise creep tests, where specimens were subjected to a constant stress rate loading followed by unloading to zero stress with intermittent creep periods on both loading and unloading paths. The strain-time response was strongly influenced by prior deformation history. Negative creep was observed on the unloading path. In addition, the behavior of the material was characterized in terms of a nonlinear viscoelastic model by means of creep and recovery tests at 288°C. The model was employed to predict the response of the material under monotonic loading/unloading and multistep load histories.

Statistical analysis of creep behavior in thermoset and thermoplastic composites reinforced with carbon and glass fibers

2020 ◽  
pp. 030932472097663
Author(s):  
Francisco Maciel Monticeli ◽  
Ana Karoline dos Reis ◽  
Roberta Motta Neves ◽  
Luis Felipe de Paula Santos ◽  
Edson Cocchieri Botelho ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Glass Fibers ◽  
Laminated Composite ◽  
Analytical Models ◽  
Thermoplastic Composites ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Thermoset Composites ◽  
Strain Behavior ◽  
Sensitivity Range

The thermoplastic and thermoset laminates reinforced with different fibers generate variations in the laminated composite mechanical behavior. This work aims to analyze thermoplastic and thermoset composites creep behavior with a reduced number of experiments, applying curve-fitting analytical models (Weibull and Findley) and statistical approach (ANOVA, F-test, and SRM) in order to describe creep behavior. Creep tests were carried out using a design of experiments to define parameter levels, aiming to reduce the number of the experiments, keeping reliability relevance. The temperature shows a stronger influence of creep deformation compared with the use of distinct materials. Thermoplastic matrices seem to be more sensitive to deformation, decreasing the reinforcement contribution. On the other hand, the creep resistance of the thermoset matrix conducts a significant contribution of strain behavior for the reinforcement used. The Findley model showed a temperature-dependent response. While, the Weibull-based model exhibits temperature and material-dependence, ensuring a greater sensitivity range of the parameters applied, an essential factor for a more realistic method description.

scholarly journals Prediction of creep behavior of laminated woven fabric with adhesive interlining under low stress in the bias direction

2016 ◽  
Vol 87 (3) ◽  
pp. 285-295 ◽  
Author(s):  
Masayuki Takatera ◽  
Ken Ishizawa ◽  
KyoungOk Kim
Keyword(s):  
Creep Strain ◽  
Creep Behavior ◽  
Viscoelastic Model ◽  
Element Model ◽  
Woven Fabric ◽  
Creep Model ◽  
Creep Tests ◽  
Viscoelastic Models ◽  
Experimental Creep ◽  
The Face

The effect of adhesive interlining on the creep behavior of a woven fabric in the bias direction was investigated. Three-element viscoelastic models were used to approximate the creep behavior of a face fabric and adhesive interlining. The creep model of a laminated fabric comprised a six-element model in which two three-element models are connected in parallel with the three-element model. Creep tests were carried out using face fabrics, adhesive interlinings, and their laminated fabrics without and with bonding adhesive interlining by hanging samples in the 45° bias direction under their own weight for 7 days. Creep strains of face fabrics bonded with adhesive interlining were found to be weaker than those of the face fabrics. The creep behavior for the face and interlining fabrics could be approximated using the three-element viscoelastic model with appropriate parameters. The experimental creep behavior of a laminated fabric without bonding was similar to the theoretical behavior. However, the experimental creep of laminated fabrics with bonding interlining was less than the calculated creep, owing to the increase in stiffness due to the adhesive. By revising the six-element model with the strains just after hanging and for 2 days, it was possible to predict the creep strain over 7 days.

A Study of Creep Behavior of TSV-Cu Based on Nanoindentaion Creep Test

2016 ◽  
Vol 32 (6) ◽  
pp. 717-724 ◽  
Author(s):  
W. Wu ◽  
F. Qin ◽  
T. An ◽  
P. Chen
Keyword(s):  
Strain Rate ◽  
Creep Behavior ◽  
Rate Sensitivity ◽  
Constant Load ◽  
Mean Value ◽  
Creep Tests ◽  
Rate Method ◽  
The Mean ◽  
Previous Loading ◽  
Indentation Strain

AbstractThrough-Silicon-Via (TSV) is considered to be the most potential solution for 3D electronic packaging, and the mechanical properties of TSV-Cu are critical for TSV reliability improving. In this paper, to make deeply understand the creep behavior of TSV-Cu, nanoindentation creep tests were conducted to obtain its creep parameters. At first, the TSV specimens were fabricated by means of a typical TSV manufacturing process. Then a combination programmable procedure of the constant indentation strain rate method and the constant load method was employed to study the creep behavior of TSV-Cu. To understand the influence of the previous loading schemes, including the different values of the indentation strain and the maximum depths, the nanoindentation creep tests under different loading conditions were conducted. The values of creep strain rate sensitivity m were derived from the corresponding displacement-holding time curves, and the mean value of m finally determined was 0.0149. The value of m is considered no obvious correlation with the different indentation strain rates and the maximum depths by this method. Furthermore, the mechanism for the room temperature creep was also discussed, and the grain boundaries might play an significant role in this creep behavior.

Creep Model Based on Theta Projection and Omega Method for Predicting the Creep Behavior of Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 533-536
Author(s):  
Bong Min Song ◽  
Jong Yup Kim ◽  
Joon Hyun Lee
Keyword(s):  
Creep Behavior ◽  
Constant Load ◽  
Control Mode ◽  
Creep Model ◽  
Test Results ◽  
Creep Data ◽  
Creep Tests ◽  
Omega Method ◽  
Improved Model ◽  
Term Creep

Creep testing of Alloy 718 has been carried out at various loads in the temperature range near 650°C in constant load control mode in order to understand how to predict the creep behavior including tertiary creep. The test results have been used for evaluating the existed models, such as Theta projection and Omega method that have been widely used for predicting long term creep strain and rupture time. After determining variables and material parameters of each method with the test results, estimated creep data from each model have been compared with the each measured creep data from the creep tests. The root cause of the discrepancy between estimated and measured data has been analyzed in order to improve the existed methods. The reliability of the improved model has been evaluated in relation to creep data.

The Rate (Time)-Dependent Mechanical Behavior of the PMR-15 Thermoset Polymer at 316°C: Experiments and Modeling

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. B. Ruggles-Wrenn ◽  
O. Ozmen
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Inelastic Deformation ◽  
Rate Sensitivity ◽  
Experimental Program ◽  
Strain Rates ◽  
Neat Resin ◽  
Strain Behavior ◽  
Thermoset Polymer

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 316°C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain-controlled loading were examined. Positive, nonlinear strain rate sensitivity is observed in monotonic loading. The material exhibits nonlinear, “curved” stress-strain behavior during unloading at all strain rates. The recovery of strain at zero stress is strongly influenced by the prior strain rate. The prior strain rate also has a profound effect on relaxation behavior. Likewise, creep response is significantly influenced by the prior strain rate. The experimental data are modeled with the viscoplasticity theory based on overstress (VBO). The comparison with experimental data demonstrates that the VBO successfully predicts the inelastic deformation behavior of the PMR-15 polymer under various test histories at 316°C.

Evaluation of Short-term Creep Behavior of PE-HD after Aging in Oil Derivatives

2018 ◽  
Vol 26 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Ayrton Alef Castanheira Pereira ◽  
José Roberto Moraes d'Almeida ◽  
Thiago Motta Linhares Castro
Keyword(s):  
Creep Behavior ◽  
Diesel Oil ◽  
Aging Effects ◽  
Short Term ◽  
Creep Tests ◽  
Before And After ◽  
Oil Derivatives ◽  
Term Creep ◽  
Effects Of Aging ◽  
Short Term Creep

The creep behavior of a high density polyethylene (PE-HD) was evaluated before and after aging in contact with gasoline and diesel oil. Four viscoelastic models were used to assess changes in creep properties of the material: three parameters model, four parameters model, stretched Burgers model and Findley Law. Viscoelastic properties, stationary creep rate and compliance were used to analyze and compare the behavior between samples. A strain increase could be seen in aged samples in comparison with as-received ones, caused by plasticization due to aging effects. An increase in flexibility and decrease in stiffness in aged samples was also noted. This work also shows that the effects of aging on the creep response of a polymeric material can be analyzed using short term creep tests.

Creep Behavior of Building Silicone Sealant under Long-Term External Loading and its Time-Stress Equivalence

2014 ◽  
Vol 633 ◽  
pp. 451-454
Author(s):  
Xiao Gen Liu ◽  
Yi Wang Bao ◽  
Xiu Fang Wang
Keyword(s):  
Creep Curve ◽  
Creep Behavior ◽  
External Loading ◽  
Nonlinear Creep ◽  
Creep Tests ◽  
Time Stress ◽  
Silicone Sealant ◽  
Term Creep ◽  
Term Performance

The main mechanics behavior character of building silicone sealant is its time dependence£¬which lies in the existence of the interior timepiece or the characteristic time. The creep behaviors were fundamental to evaluating the long-term performance of the building silicone sealant under long-term external loading. A series of creep tests of building silicone sealant were conducted in the laboratory under different combinations of external loads, the characteristics of the creep curve were obtained. In this work, the creep behaviors of building silicone sealant were also investigated under various temperatures at invariable stress. The test measurements show that the creep behavior of building silicone sealant are nonlinear, Nonlinear creep behavior is analyzed by means of the equivalence principle of time-stress, the main creep curve under reference stress was obtained by fitting with the viscoelastic rheological model. So the long-term creep behavior of the building silicone sealant under lower stress can be predicted by short-term creep behavior under higher stress.

Creep characterization of gels and nonlinear viscoelastic material model

2016 ◽  
Vol 30 (18) ◽  
pp. 1650225 ◽  
Author(s):  
Kiyotaka Ishikawa ◽  
Masaki Fujikawa ◽  
Chobin Makabe ◽  
Kou Tanaka
Keyword(s):  
Creep Behavior ◽  
Viscoelastic Model ◽  
Predictive Performance ◽  
Material Model ◽  
Good Reproducibility ◽  
Creep Tests ◽  
Material Constants ◽  
Nonlinear Viscoelastic ◽  
Three Stages

In this paper, we examine gel creep behavior and develop a material model for useful and simple numerical simulation of this behavior. This study has three stages and aims: (1) gel creep behavior is examined; (2) the material model is determined and the material constants are identified; and (3) the versatility of the material model and the constants are evaluated. The creep behavior is found to be independent of the initial stress level in the present experiment. Thus, the viscoelastic model proposed by Simo is selected, and its material constants are identified using the results of creep tests. Moreover, from the results of numerical calculations and experiments, it is found that the chosen material model has good reproducibility, predictive performance and high versatility.

Creep Behavior and Microstructural Stability of Ti-46Al-9Nb with Different Microstructures

2004 ◽  
Vol 842 ◽  
Author(s):  
S. Bystrzanowski ◽  
A. Bartels ◽  
H. Clemens ◽  
R. Gerling ◽  
F.-P. Schimansky ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Sheet Material ◽  
Lamellar Microstructure ◽  
Lamellar Spacing ◽  
Activation Energies ◽  
Microstructural Stability ◽  
X Ray Diffraction ◽  
Creep Tests ◽  
Apparent Activation Energies ◽  
Term Creep

ABSTRACTIn this paper the creep behavior and the microstructural stability of Ti-46Al-9Nb (in at.%) sheet material were investigated in the temperature range of 700°C to 815°C. The study involves three different types of microstructure, namely fully lamellar with narrow lamellar spacing, duplex and massively transformed. Short-term creep experiments conducted at 700°C and 225 MPa confirmed that the lamellar microstructure with narrow lamellar spacing exhibits a much higher creep resistance when compared to the massively transformed and duplex ones. During longterm creep tests up to 1500 hours stress exponents (in the range of 4.4 to 5.8) and apparent activation energies (of about 4 eV) have been estimated by means of load and temperature changes, respectively. Both, stress exponents and activation energies suggest that under the applied conditions diffusion-assisted climb of dislocations is the dominant creep mechanism. The thermal stability of the different microstructures under various creep conditions has been analyzed by electron microscopy and X-ray diffraction. Our investigations revealed considerable stress and temperature induced microstructural changes which are reflected in the dissolution of the α2 phase accompanied by precipitation of a Ti/Nb - rich phase situated at grain boundaries. This phase was identified as a ω-related phase with B82-type structure. It was shown, that in particular the duplex microstructure is prone to such microstructural instabilities.

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