Florida Institute of Technology

College of Engineering

Department of chemical Engineering

CHE 3265 – Materials Laboratory

CTE

Experiment Performed on: March 28, 2016

Report Submitted: April 11, 2016

Instructor: Prof. Vipuil Kishore

GSA: Thuy-Uyen Nguyen

Performed by: Abdullah Kurdi

Introduction:

Creep is the deformation of a solid material due to the effect of constant mechanical

stress at elevated temperatures, greater than a third of the melting point. It is an outcome of a

long term exposure of load at elevated temperatures, diffusion driven, which results in a

permanent deformation and rupture of the material.

In this experiment, the creep behavior was studied on Dr. Engblom’s plastic wood

sample, which is a composite of plastic and wood shavings and is at a temperature greater than a

third of it’s melting point just at room temperature. The study was conducted by applying

constant load on the sample and measuring the deflection as a function of time.

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Experimental Procedure:

Figure 1 below shows the overall setup of the apparatus. The wood sample is held by two

stands with clamps on both sides. A jominy bar was placed above the middle of the wood sample

to apply the constant static load and a dial gage was placed under the sample to measure the

deflection as time progresses. The following equation was used to calculate creep:

Creep=dϵdt

=K σn exp (−EcreepRT )Where K, n, and Ecreep are constants that are experimentally determined

Ecreep is the activation energy for creep

n is the creep exponent

R is the gas constant

T is the temperature in Kelvin

is the stress

dϵ is the change in strain

dt is the change in time

Figure 1: Apparatus setup for the creep study1

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Results:

Figure 2: a log-log plot of Deflection versus Time1

From Figure 2, it can be noticed that the

Discussion:

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References:

1. Dr. Kishore, Canvas.fit.edu, Materials Laboratory CHE 3265-01

Appendix A: Sample Calculations

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Appendix B: Data Sheet

Table 1: Datasheet1

Dial Gauge (in) Time (sec) Deflection (inches)

0.00000 0 0.00000

0.01750 1 0.01750

0.01862 5 0.01862

0.01905 10 0.01905

0.01935 15 0.01935

0.01950 20 0.01950

0.01967 30 0.01967

0.01992 45 0.01992

0.02020 60 0.02020

0.02021 100 0.02021

Table 2: Results and Errors1

log (time), time in sec log (Deflection), Deflection in inches Error in Time (sec) Error in Dial Gauge Reading (in)

0.000 0.0000

0.000 -1.7570 0.5 0.0001

0.699 -1.7300 1 0.00001

1.000 -1.7201 1 0.00001

1.176 -1.7133 1 0.00001

1.301 -1.7100 1 0.00001

1.477 -1.7062 1 0.00001

1.653 -1.7007 1 0.00001

1.778 -1.6946 1 0.00001

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2.000 -1.6944 1 0.00001

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Appendix C: DataFit

DataFit version 6.1.10Results from project "Untitled1"Equation ID: a*x+bNumber of observations = 9Number of missing observations = 0Solver type: LinearSum of Residuals = 4.88498130835069E-15Average Residual = 5.42775700927854E-16Residual Sum of Squares (Absolute) = 5.34333330167226E-05Residual Sum of Squares (Relative) = 5.34333330167226E-05Standard Error of the Estimate = 2.76284876316154E-03Coefficient of Multiple Determination (R^2) = 0.9830743273Proportion of Variance Explained = 98.30743273%Adjusted coefficient of multiple determination (Ra^2) = 0.9806563741Durbin-Watson statistic = 1.46076432655653Regression Variable ResultsVariable Value Standard Errort-ratio Prob(t)a 0.03222368007 0.0015981072 20.16365364 0.0b -1.753718586 0.00217296877 -807.0611093 0.068% Confidence IntervalsVariable Value 68% (+/-) Lower Limit Upper Limita 0.03222368007 0.001710454137 0.03051322594 0.03393413421b -1.753718586 0.002325728474 -1.756044314 -1.75139285790% Confidence IntervalsVariable Value 90% (+/-) Lower Limit Upper Limita 0.03222368007 0.003027773902 0.02919590617 0.03525145398b -1.753718586 0.004116906631 -1.757835492 -1.74960167995% Confidence IntervalsVariable Value 95% (+/-) Lower Limit Upper Limita 0.03222368007 0.003778884286 0.02844479579 0.03600256436b -1.753718586 0.005138201952 -1.758856788 -1.74858038499% Confidence IntervalsVariable Value 99% (+/-) Lower Limit Upper Limita 0.03222368007 0.005592576148 0.02663110393 0.03781625622b -1.753718586 0.007604304209 -1.76132289 -1.746114281Variance AnalysisSource DF Sum of Squares Mean Square F RatioProb(F)Regression 1 0.003103506667 0.003103506667 406.5729282 0Error 7 5.343333302E-005 7.633333288E-006

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Total 8 0.00315694

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