Assessment of Damage and Long-Term Strength of Polyethylene
Tensile strength of polyethylene is examined at various crosshead speeds using cylindrical specimens of 20 mm in gauge length.Through monotonic stretch with intermittent halt for load relaxation,the study shows that long-term tensile strength of polyethylene should be around half of the short-term strength determined in the standard test conditions.The study discovers a transition in the localized deformation (commonly known as necking),of which the appearance changes from opaque white to translucent when the crosshead speed is reduced from 0.05 to 0.01 mm/min,possibly due to the suppression of cavitation damage at the low crosshead speed.At a sufficiently high crosshead speed,damage generation can occur at a threshold strain as low as 4% which is way below the yield strain of the material.It is therefore concluded that determining long-term tensile strength of polyethylene needs to consider accumulation of the damage.Since this type of damage is not quantified in any of current standard methods,the study suggests that results from those tests need to be analyzed carefully to ascertain their validity for characterizing long-term performance of polyethylene products.
Long-term strength polyethylene damage neck
P-Y Ben Jar
Department of Mechanical Engineering,University of Alberta,Edmonton,AB,T6G 2G8,Canada
国际会议
北京
英文
1-9
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）