Self-heating in materials with high energy dissipation such as polymers and polymer composites under vibrational cyclic loading can lead to catastrophic failure known as “heat explosion”. Predicting safe temperature increases is essential for critical structural applications. The properties of many polymer materials are strongly temperature dependent, thus emphasizing the importance of heat generation from mechanical vibrations. The analysis is based on the model predicting stress induced heat increase for viscoelastic materials under cyclic loading conditions. A set of stress-strain and creep experiments on PMMA at ambient and elevated temperatures was performed together with the mechanical engineering department. The data was used to determine the model parameters for viscoelastic mechanical stresses. Additional data from experimental testing of PMMA under vibrational loading has been analyzed and used to verify the developed model.