Clyde Spencer Hutchins

Influence of Interfacial Bond Strength on Fatigue Life and Thermo-Mechanical Behavior of a Particulate Composite: An Experimental Study

Experimental studies conducted on a particular cast acrylic composite demonstrate the significant influence of the interfacial bond strength between filler particles and the polymer matrix on the fatigue life, and mechanical properties. The composite studied in this project is composed of a ductile matrix, which is lightly cross-linked poly-methyl methacrylate (PMMA) and hard, brittle alumina trihydrate (ATH) agglomerate particle filler. In the study, high, moderate, and low levels of interfacial adhesion between the matrix and the filler are investigated, while all the other material properties are kept constant. Monotonic tension and fatigue tests are conducted at different temperatures. Material degradation is presented in terms of elastic modulus degradation, load-drop parameter, and plastic strain range.

Time Dependent Behavior of a Particle Filled Composite PMMA/ATH at Elevated Temperatures

Creep behavior of particle filled acrylic composite materials become a major concern when they are used at elevated temperatures. Therefore, for elevated temperature finite element simulations any constitutive modeling requires time— temperature dependent material properties. Unfortunately, this type of data is very difficult to come across in the literature, due to a very long time needed to conduct creep testing. In this study, the creep properties of acrylic casting dispersion PMMA/ ATH were obtained experimentally and the observed characteristics of this material are presented with the experimental data. The underlying deformation mechanisms and the steady-state creep response are also discussed.

Failure Mechanisms in PMMA/ATH Acrylic Casting Dispersion

Acrylic casting dispersion is used to fabricate particulate composites such as poly-methyl methacrylate (PMMA) filled with a fine dispersion alumina trihydrate (ATH). This composite is subjected to severe temperature variations during in-service conditions, giving rise to high thermal stresses which lead to failure by cracking. The influence of the interfacial bond strength between a particle and the matrix on the failure mechanism of acrylic casting dispersion has been investigated using in situ observations during tensile and compressive loadings. Experiments show that the failure in pure tension occurs differently than in flexure loading where the failure process is believed to be more complex. During tensile loading, it is observed that macroscopic fracture is initiated in the clusters of the reinforcing particles because of the strong interfacial bonding strength between the filler particles and matrix. For weak interfacial bond strength, the macroscopic fracture is initiated by separation of filler agglomerates from the matrix.

Experimental study of failure mechanisms in particle filled acrylic composites

Particle filled solid surface composites are used to fabricate kitchen countertops and sinks which may be subjected to severe temperature variations, giving rise to high thermal stresses. These stresses may lead to failure by cracking in regions subjected to large temperature variation. An aim of this paper is to investigate mechanisms of failure in solid surface materials using in situ observations during tensile, compressive and fatigue loading and to define test configurations that give meaningful measurements of material properties. Experiments show that the failure in tension occurs in several stages. In flexural loading the failure process is more complex. Consequently, flexural testing should not be used as a substitute for the measurement of ultimate tensile strength in a particle filled solid surface composite. The application of conventional damage mechanics to describe the failure of test specimens is also discussed.