DLL 06: Cantilever beam with eccentric mass – eigenfrequencies

Description

Material	For bar AB	Modulus of elasticity
		Density
	For bar BC1	Modulus of elasticity
		Density
Geometry	Cross-section	For all bars
	Boundary conditions	In point A	Fixed support
Loads		Case 1:	Mass of 1000 kg in point B. Bar BC is not present.
		Case 2:	Mass of 1000 kg in point C. Bar BC is present.
Mesh		No. of divisions	12

^{1. The eccentricity of the mass is created by adding bar BC to the model. The purpose is that bar BC is significantly stiffer than bar AB.}

Results

Case 1

Eigen mode	Shape	Independent reference	Diamonds	Difference
1		1.65Hz	1.655Hz	-0.30%
2		16.07Hz	16.07Hz	0.00%
3		50.02Hz	50.027Hz	-0.01%
4		76.47Hz	76.45Hz	0.03%
5		80.47Hz	80.505Hz	-0.04%
6		103.2Hz	103.235Hz	-0.03%

Case 2

Eigen mode	Shape	Independent reference	Diamonds	Difference
1		1.636Hz	1.635Hz	0.06%
2		1.642Hz	1.641Hz	0.06%
3		13.46Hz	13.391Hz	0.52%
4		13.59Hz	13.562Hz	0.21%
5		28.9Hz	28.821Hz	0.27%
6		31.96Hz	30.872Hz	3.52%
7		61.61Hz	61.618Hz	-0.01%
8		63.93Hz	61.969Hz	3.16%

References