Cross-linked polyethylene is widely used in the manufacturing of rotationally molded tanks for the agriculture, petroleum, and chemical industries. These tanks are exposed to a number of environmental effects, which can lead to material degradation. Measuring ultrasonic wave speed change in the outer wall of the tank is a method that shows promise for evaluating the ultraviolet (UV) degradation effects. In order to evaluate the UV effects in the field, however, the effect of stress and temperature on the wave speed first must be established. A series of tests was performed to establish the ultrasonic properties in cross-linked as well as linear polyethylene at a range of temperatures from $−6°Cto44°C$ ($22°Fto112°F$). The change is linear, as expected. For the stress tests, the velocity decreased with tension, also as expected. Tests were performed from approximately $689kPato9.6MPa$$(100to1400psi)$. Results from these tests were incorporated into the overall algorithm used for evaluating tank degradation.

1.
Beall
,
G.
, 1998,
Rotational Molding Design, Materials, Tooling, and Processing
,
Hansar Publishers
, Munich.
2.
Crawford
,
R. J.
, 1996,
Rotational Molding of Plastics
,
RSP
, Taunton, England.
4.
Bray
,
D. E.
, and
Stanley
,
Rod K.
, 1997,
Nondestructive Evaluation
,
CRC Press
, Boca Raton, FL.
5.
Egle
,
D. M.
, and
Bray
,
D. E.
, “
Nondestructive Measurement of Longitudinal Rail Stresses: Applications of the Acoustoelastic Effect to Rail Stress Measurement
6.
,
K.
, 2001, “
Effects of Temperature on High Density Polyethylene Piping and Accuracy of Ultrasonic Thickness Gaging
,”
Mater. Eval.
0025-5327,
59
, pp.
1033
1036
.
7.
Egle
,
D. M.
, and
Bray
,
D. E.
, 1976, “
Measurements of Acoustoelastic and Third Order Elastic Constants for Rail Steel
,”
J. Acoust. Soc. Am.
0001-4966,
60
, pp.
741
744
.
8.
Shaikh
,
N.
, 1992, “
Transducers and Technique for Ultrasonic Nondestructive Evaluation of Structural Plastics
,” in
Review of Progress in Quantitative Nondestructive Evaluation
, Vol.
11
,
D. O.
Thompson
and
D.
Chementi
, eds.,
Plenum Press
, New York, pp.
1831
1835
.
9.
Ensminger
,
D.
, 1988,
Ultrasonics
,
Marcel Dekker, Inc.
, New York.
10.
Birks
,
A. S.
,
Green
,
Robert E.
, Jr.
, and
McIntire
,
P.
, 1991,
Nondestructive Testing Handbook
,
American Society for Nondestructive Testing
, Columbus, OH.
11.
Vary
,
A.
, 1988, “
Concepts for Interrelating Ultrasonic Attenuation, Microstructure and Fracture Toughness in Polycrystalline Solids
,”
Mater. Eval.
0025-5327,
46
, pp.
642
649
.
12.
McGrath
,
S. P.
, 1997, “
Using Ultrasonic Techniques to Predict Fracture Toughness of AISI 4137 Alloy Steel
,” Masters Thesis, Department of Mechanical Engineering, Texas A&M University, College Station, TX.
13.
Vela
,
J.
, 2002, “
Ultrasonic Stress Measurements in High-Density Polyethylene
,” Senior Thesis, Department of Mechanical Engineering, Texas A&M University, College Station, TX.