References
[1] Zhu, J., Z. R. L. Taylor, and O. C. Zienkiewicz. “The finite element method: its basis and fundamentals.” (2005): 54-102.
[2] Felippa, Carlos A., Qiong Guo, and K. C. Park. “Mass matrix templates: General description and 1d examples.” Archives of Computational Methods in Engineering 22.1 (2015): 1-65.
See
1、https://scicomp.stackexchange.com/questions/19704/how-to-formulate-lumped-mass-matrix-in-fem
2、https://scicomp.stackexchange.com/questions/24293/effects-of-lumping-mass-matrix