Concept question Why is the element stiffness matrix singular in a finite element formulation? 1. So that it can accomodate rigid element dis- placements without introducing spurious nodal 2 Because we made a mistake in the formula- tion the stiffness matrix should not be sin- g 3. Because we havent enforced any displace ment boundary conditions(it's a variational approach after all) Statement(1) Statement(2) Statement (3) Statements(1) and (3 DKDU++++ ++++ ++++ ++++ ++++ Concept Question ++++ ++++ ++++ ++++ ++++ Why is the element stiffness matrix singular in a finite element formulation? 1. So that it can accomodate rigid element dis￾placements without introducing spurious nodal forces. 2. Because we made a mistake in the formula￾tion, the stiffness matrix should not be sin￾gular. 3. Because we haven’t enforced any displace￾ment boundary conditions (it’s a variational approach after all) • ++++ Statement (1) • ++++ Statement (2) • ++++ Statement (3) • ++++ Statements (1) and (3) • ++++ DKDU