Determining stability of side frames of skeletal furniture requires knowledge of values of both vertical load F and horizontal load H (Fig. 6.91). Value of the force F can be expressed in the form:
and the value of the force H:
a width of the furniture base,
e arm of acting of vertical force in relation to the edge of the base, x location of the furniture’s centre of gravity,
h height of the backrest,
2Q sum of the mass loads,
Fkr critical load.
The most common cause of the loss of stability of furniture, by moving the centre of gravity outside of the base area, is the erroneous distribution of elements. For asymmetrical constructions (Fig. 6.91b), it is necessary to check the position of the centre of weight x and determine the permissible loads H and F, causing the chair or armchair to tip over.