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Due to the increasing demand for energy-efficient vehicles, there is an increasing need to design lightweight structures and these invariably use lightweight materials which are difficult or impossible to weld. Clinching technology offers an alternative to spot welding especially for joining sheet materials. The present paper deals with transverse free vibration analysis of single lap jointed encastre clinched joints using three dimensional finite element methods (FEM). The focus of the analysis Is to reveal the influence on the natural frequencies, natural frequency ratios and mode shapes of these joints caused by variations in the material properties of the sheet materials. Numerical examples show that the transverse natural frequencies of single lap jointed encastre clinched joints increase significantly as the Young's modulus of the sheets increase, but only slight changes are encountered for variations of Poisson's ratio. The mode shapes show that there are different deformations in the jointed section of clinched joints compared with the reference cantilevered beams without joint. These different deformations may cause different natural frequency values and different stress distributions. As expected, odd modes shapes were found to be symmetrical about the mid-length position and even modes were anti-symmetrical. It is also found that the material densities of the sheets have significant effects on the transverse free vibration characteristics of single lap jointed encastre clinched joints. [ABSTRACT FROM AUTHOR]