Experimental Measurements of Mechanical Properties of PUR Foam Used for Testing Medical Devices and Instruments Depending on Temperature, Density and Strain Rate

Abstract

Rigid polyurethane (PUR) foam is products used as a biomedical material for medical device testing. Thermal stability is a very important parameter for evaluating the feasibility of use for testing surgical instrument load during drilling. This work aimed to perform experimental measurements to determine the dependence of the mechanical properties of a certified PUR on temperature, strain rate and density. Experimental measurements were realised for three types of the PUR samples with different density 10, 25 and 40 pounds per cubic foot. The samples were characterised in terms of their mechanical properties evaluated from tensile and compression tests at temperatures of 25 °C, 90 °C and 155 °C. Furthermore, the structures of the samples were characterised using optical microscope, their thermal properties were characterised by thermogravimetric analysis, and their density and stiffness with the effect of temperature was monitored. The results show that it is optimal not only for mechanical testing but also for testing surgical instruments that generate heat during machining. On the basis of experimental measurements and evaluations of the obtained values, the tested materials are suitable for mechanical testing of medical devices. At the same time, this material is also suitable for testing surgical instruments that generate heat during machining.

Is Fracture Toughness of PUR Foams a Material Property? A Statistical Approach

“…For the statistical analysis it is denoted Y for the response variable, the mean value of the fracture toughness and five predictor variable: X1 -specimen type (1 = "SENB-TPB", 2 = "SENB-FPB", 3 = "SEC", 4 = "ASCB", 5 = "ENDB"), X2-loading speed (2 or 50), X3 -density (100 kg/m 3 , 145 kg/m 3 or 300 kg/m 3 ), X4 = direction plane (1 = "in-plane-flow", 0 = "out of plane-rise"), X5 = number of measurements (2,3,4,5).…”

“…For structural components, strength and fracture toughness are two important mechanical properties [1,2]. Yield strength is the measure of the stress that a material can withstand before plastic deformation, while the tensile strength is a measure of the maximum stress that a material can support before starting to fracture [3]. Fracture toughness is a measure of the energy required to fracture a material that contains a crack [4].…”

“…Marsavina and Linul [19] experimentally investigated closed-cell rigid PUR foams with densities between 40 kg/m 3 and 200 kg/m 3 using SENB specimens loaded in three-point bending and determined the mode I fracture toughness between 0.034-0.39 MPa•m 0.5 . Fracture toughness of low-density rigid PUR (32-84 kg/m 3 ) was obtained by Andersons et al [11] in the range 0.022-0.058 MPa•m 0.5 using Compact Tension (CT) specimens.…”

Experimental investigation of the temperature during bone drilling using thermocouples and numerical finite element analysis

“…A PUR block with installed thermocouples for detection of the temperature inside the block was fixed in a table in the same horizontal axis as the surgical drilling machine, and in the drilling direction. In front of the PUR block an IR camera (FLIR) was installed for recording the temperature at the cutting edge of experimental drills during perforating the PUR Block [32].…”

“…The axial movement of a drill is one of the important parameters [34,35], in our case it was in all cases 30 mm/min, which was discussed with an experienced dentist. The influence of a drill diameter and drilling force were not investigated [32,36].…”