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1 无力矩理论及其适用范围化工容器及化工设备的外壳,一般都属于薄壁回转壳体,通常是承受轴对称载荷,如内压、外压、液压和自重等。对这类壳体进行分析,有2种理论;一种是无力矩理论,又称薄膜理论。它假定壁厚与直径相比(S/D_i)很小,因而可将壳壁当作薄膜,认为它只能承受拉应力和压应力,而对于相对较小的弯曲应力则未予考虑,即考虑轴向应力σ_ψ及切向(周向)应力σ_θ,而对于相对较小的σ_τ(径向应力),则忽略不计。这种壳体中存在的应力,称为薄膜应力;另一种理论认为壳体虽然很薄,但仍有一定厚度,有一定的刚度,因而壳体中除拉应力或压应力外,还存在弯矩和弯曲应力。这种理论为有力矩理论。
1 Momentless theory and its scope Chemical containers and chemical equipment shell, are generally belong to the thin-walled shell, usually to withstand axisymmetric loads, such as internal pressure, external pressure, hydraulic and self-weight. Analysis of such shells, there are two kinds of theory; one is the momentless theory, also known as thin film theory. It assumes that the wall thickness is small compared to the diameter (S / D_i) so that the shell wall can be considered as a thin film, which is considered to be able to withstand both tensile and compressive stresses, but not considered for relatively small bending stresses, namely The axial stress σ_ψ and the tangential (circumferential) stress σ_θ are taken into account, whereas for a relatively small σ_τ (radial stress), negligible. The stress in this kind of shell is called the film stress. Another theory is that although the shell is very thin, it still has a certain thickness and a certain rigidity, so the shell can exist in addition to the tensile stress or compressive stress Bending moment and bending stress. This theory is a moment theory.