| Summary |
The form-finding is analyzed by the tangent stiffness method. Two expressions of geometrical stiffness of a soap film element are applied for the form-finding. One tangent geometrical stiffness of the triangle element is derived by the condition of constant element forces in side directions. The other is derived by the condition of a constant tensile density in the element. in both methodEa node can be treated as having only one degree of freedom in normal direction on the formEbecause the form does not have any stiffness against nodal displacement on the soap film surface theoretically. Comparing the two methods with some computationsEin either caseEwe can get rational solutions with satisfactory convergence.
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