ASTM D2659-11 Standard Test Method for Column Crushing Properties of Blown Thermoplastic Containers

The American Society for Testing and Materials (ASTM) standard "ASTM D2659-11 Standard Test Method for Column Crushing Properties of Blown Thermoplastic Containers" describes a test method for determining the mechanical properties of blown thermoplastic containers loaded under column crushing conditions at a constant pressure deflection rate, whether commercially or laboratory blown. Although this test method was developed specifically for blow molded containers, the general procedure can also be applied to containers of suitable geometries produced by thermoforming, injection molding, and other similar methods.

For the purposes of this standard, the following terms and definitions apply:

• The fracture yield load refers to the initial load at which deflection increases without an increase in load in a compressive fracture test (expressed in kilogram load units). In some cases, usually as a result of the design or style characteristics of a particular vessel or both, multiple values ​​of the fracture yield load may be observed, i.e. a small deflection occurs without an increase in the fracture load or with a decrease, followed by a continuation of the normal fracture load variation with deflection. This phenomenon cannot be ignored in the evaluation of the column crushing properties of an inflated thermoplastic vessel, as it can be a very useful identified failure point for the application in question. The load at which this sudden change occurs may be selected as a fracture yield load for the study. In such a case, the final report should be accompanied by an appropriate description of the selected fracture yield load.
• The crushing load at fracture refers to the crushing load (expressed in kilograms) applied to a blown thermoplastic container that causes a fracture by breaking or separating the material in any part of the container.
• The crushing yield deflection load refers to the reduction in length of the cup specimen produced at the crushing yield load along the centerline (crushing axis) of the test (expressed in millimeters).
• Apparent crushing stiffness expresses the ratio of the crushing load to the corresponding deflection at a point on the linear portion of the crushing load deflection curve (expressed in Newtons per metre).

Column crush tests provide information on the crushing properties of blown thermoplastic containers only when used under conditions approximating those under which the tests were conducted.

Column crushing properties include crushing yield load, deflection at crushing yield load, crushing load at fracture, and apparent crushing hardness. Blown thermoplastic containers made of materials with low ductility may fail to crush by brittle fracture. In such cases, the crushing yield load is equivalent to the crushing load at fracture. Blown thermoplastic containers made of ductile materials will not always exhibit a crushing yield load, although they will normally provide a crushing yield load value.

Column crushing tests provide a standard method of obtaining data for research and development, applications, design, quality control, acceptance or rejection according to specifications, and special purposes. The tests cannot be considered significant for engineering design in applications that differ greatly from the load-time scale of the standard test. Such applications require additional tests such as impact, creep, and fatigue.

The main equipment used in these tests includes:

• Testing machine: Any suitable testing machine capable of controlling the constant-speed movement of the crosshead and consisting essentially of the following: The drive mechanism thereon is a drive mechanism which gives the moving member of the crosshead a uniform, controlled speed relative to the fixed member. The load indicator is a load indicating mechanism capable of indicating the total crushing load carried by the test specimen. The mechanism shall be substantially free from inertia lag at the specified test rate and shall indicate the crushing load with 61 percent accuracy. The accuracy of the testing machine shall be verified at least annually.
• Extensometer: An instrument suitable for determining the distance between two surfaces to which a load is applied to a test specimen at any time during a test. It is desirable that this instrument automatically record this distance or any change in the test specimen as a function of the crushing load. The instrument shall be substantially free of inertial lag at the specified loading rate and shall comply with the requirements for a Class B-83 extensometer as defined in ASTM E23-2.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also appropriate test services in accordance with the "ASTM D2659-11 Standard test method for column crushing properties of blown thermoplastic containers" standard.