一、前言

  SESAM （Super Element Structure Analysis Module）是由挪威船级社（DNV-GL）开发的一款有限元分析（FEA）系统，它以 GeniE、HydroD 和 DeepC 等模块为核心，是海洋工程结构分析的行业标准软件，主要用于海工结构的强度评估、波浪荷载计算和系泊系统分析等。 GeniE、HydroD 和 DeepC 分别是 Sesam 系统的固定式结构分析模块、漂浮式结构分析模块和系泊系统分析模块。GeniE is Sesam modules for fixed structures.

Sesam Overview

  属性的定义与赋予是进行海工结构分析的前提，它直接影响着结构的刚度矩阵、质量矩阵等的确定。材料属性、截面属性、局部轴方向等是经常用到的属性，除此之外，根据分析的不同，可能用到一些特殊的属性。例如，导管架分析时需定义 Hydro 属性（Morison coefficients and Marine Growth）。

属性对话框

二、材料属性

新建材料

Mat1 = MaterialLinear(235, 7850 kg/m^3, 2.1e+11 Pa, 0.3, 1.2e-05 delC^-1, 0.03 N*s/m);
Mat2 = MaterialLinear(355, 7850 kg/m^3, 2.1e+11 Pa, 0.3, 1.2e-05 delC^-1, 0.03 N*s/m);

JS Command Example

三、截面属性

3.1 梁横截面

新建截面 梁截面类型：Pipe、Bar、Box、I、L、Channel、I-Unsymmetrical、General 和 Cone 。


General Section Properties

序号	参数	英文	中文
01	Area	Beam cross sectional area	梁的横截面积
02	Ix/IP	Torsional moment of inertia about shear centre	截面对剪切中心的扭转惯性矩/截面对剪心极惯性矩
03	Iy	Moment of inertia (2nd moment of area) about y-axis	截面对 y 轴的惯性矩（面积的二阶矩）
04	Iz	Moment of inertia (2nd moment of area) about Z-axis	截面对 Z 轴的惯性矩（面积的二阶矩）
05	Iyz	Product of inertia about y- and z-axes	截面对 y 轴和 z 轴的惯性积
06	Wx min	Minimum torsional sectional modulus about shear centre	截面对剪切中心的最小扭转截面模量/抗扭截面模量
07	Wy min	Minimum sectional modulus about y-axis	截面对 y 轴的最小截面模量/抗弯截面模量
08	Wz min	Minimum sectional modulus about z-axis	截面对 z 轴的最小截面模量/抗弯截面模量
09	Shary	Shear area in the direction of y-axis	y 轴方向的剪切面积
10	Sharz	Shear area in the direction of z-axis	z 轴方向的剪切面积
11	Shceny	Shear centre location y-component	剪切中心位置 y 分量
12	Shcenz	Shear centre location z-component	剪切中心位置 z 分量
13	Sy	Static area moment about y-axis	截面对 y 轴的静矩/面积矩
14	Sz	Static area moment about z-axis	截面对 z 轴的静矩/面积矩
15	Wy	Static area moment about y-axis	截面对 y 轴的塑性截面模量/塑性抗弯截面模量
16	Wz	Static area moment about z-axis	截面对 z 轴的塑性截面模量/塑性抗弯截面模量

MyBar = BarSection(.2, .05);
MyBox = BoxSection(.8, .5, .04, .04, .04);
MyI = ISection(1.2, .7, .04, .06);
MyL = LSection(.4, .03, .2, .03);
MyChannel = ChannelSection(.5, .2, .02, .04, 0 m);
MyIUnsymmetrical = UnsymISection(1.2, .04, .6, .2, .06, .7, .5, .06);
MyGeneral = GeneralSection(0.1212, 0.000128304, 0.0294681, 0.00404561, -0.00556681, 0.0021384, 0.0469075, 0.00846853, 0.062287, 0.0421075, -0.0194624, -0.117854, 0.0279933, 0.00779413);
MyGeneral.wpy = 0.05;
MyGeneral.wpz = 0.01;
MyCone = ConeSection(0.5, true);
// Log from importing sections from library:
HFRHS400X200X10 = BoxSection(400mm,200mm,10mm,10mm,10mm);
HFRHS400X200X10.description = "NVS lib : 400x200x10 NS-EN 10210";
HFRHS400X200X12 = BoxSection(400mm,200mm,12mm,12mm,12mm);
HFRHS400X200X12.description = "NVS lib : 400x200x12 NS-EN 10210";
HFRHS400X200X12_5 = BoxSection(400mm,200mm,12.5mm,12.5mm,12.5mm);
HFRHS400X200X12_5.description = "NVS lib : 400x200x12,5 NS-EN 10210";

3.2 板壳厚度

Create Thickness

Tck2 = Thickness(0.05);

3.3 截面赋予

截面的赋予

Bm1.section = Sct1;
Pl1.thickness = Tck2;

四、截面偏置

4.1 梁偏置

选择梁 >> 右键 >> Edit Beam >> Beam Offset

4.2 板壳偏置

五、局部轴方向

5.1 梁的局部轴

The Local System tab is found in both Properties and Edit Beams dialogs 选择梁 >> 右键 >> Edit Beam >> Local System

  梁的轴线即梁的局部 x 轴为梁的起点指向梁的端点，默认情况下，梁横截面的局部 z 轴由下列规定确定：对于轴线与整体 Z 轴相平行的梁，局部 z 轴指向整体 Y 轴正方向。对于轴线与整体 Z 轴不平行的梁，局部 z 轴朝上，局部 xoz 平面与整体 XOY 平面垂直。局部 y 轴由右手定则确定，如下图所示。

Default beam axis system

局部z轴方向的修改

局部x轴方向的修改

5.2 板壳的法向

  板/壳（plate/shell）局部 z 轴由右手定则根据创建板/壳时角点的顺序确定，创建多边形平板（plate）时，上述定义是明确的，当通过蒙皮、扫掠和其他方法创建复杂的壳（plate）时，这个定义并不那么容易预测。 在这种情况下，与其对壳局部 z 轴的定义进行冗长的讨论，不如仅观察结果并根据需要时翻转 z 轴。

局部 z 轴的翻转

板壳局部 z 轴的显示

六、水力属性

6.1 湿表面属性

  Wet Surface is available through the Top Dropdown Menu Edit | Properties, from the Browser and from the Context Sensitive Menu under Properties. Wet Surface is normally used in connection with Dummy Hydro Pressure, see Load Case, and hydrodynamic pressure loads computed by HydroD. 湿表面承受水动力（wet surfaces shall receive hydrodynamic loads.）湿表面的法向必须朝向外。

Create Wet Surface Properties

WS1 = WetSurface();

6.2 水动力参数

  Hydro Property 对话框可由顶部菜单 Edit ->> Properties 访问，So-called ‘hydro’ properties are relevant for wave load analysis of frame structures, i.e. running Wajac. The ‘hydro’ properties are tabulated below. Each must be assigned to a part of or the complete structure to take effect.

Hydro properties

Type of property	Category	Mandatory or optional	Number of specifications
Morison - Constant	A	Mandatory for the wet part [1]	Arbitrary
Morison - Global Direction	A	Mandatory for the wet part	Arbitrary
Morison - f(Rn; Rough)	B	Mandatory for the wet part	1
Morison - f(KC; Rough)	B	Mandatory for the wet part	1
Morison - f(Diameter)	B	Mandatory for the wet part	1
Morison By Rule	B	Mandatory for the wet part	1
Air Drag - Constant	A	Mandatory for the dry part when calculating wind loads	Arbitrary
Air Drag - f(Rn)	B	Mandatory for the dry part when calculating wind loads	1
Hydrodynamic Diameter		Optional	Arbitrary
Flooding		Optional	Arbitrary
Marine Growth - Constant	A	Optional	Arbitrary
Marine Growth - f(Z)	B	Optional	Arbitrary
Element Refinement		Optional	Arbitrary
Buoyancy Area		Optional	Arbitrary
Conductor Shielding		Optional	Arbitrary

  [1]. Strictly, definition of Morison coefficients may be skipped in which case Wajac sets Cd=0.7 and Cm=2. But as several warnings are printed by Wajac in such case it is normally better to assign the coefficients in GeniE. The properties Morison, Air Drag and Marine Growth may all be functions of one or more of the parameters: Reynolds number, Keulegan-Carpenter (KC) number, roughness height, member diameter (including any marine growth) and Z level. These methods of definition are categorised as A and B in the table above. One or both of these categories may be used for specifying a certain property but not two specifications of the same category. For example, Morison properties can be specified as both constant and function of diameter but not as functions of both Reynolds number (Rn) and diameter. As indicated in the table above, for some properties only one specification is allowed. E.g., two specifications of Morison coefficients as functions of diameter and assigned to different parts of the model is not allowed. For the optional properties, see the table above, Wajac will use default data if not specified in GeniE. For example, if no Flooding property is given all members will be non-flooded, i.e. air-filled. And if no Element Refinement property has been assigned a refinement coefficient of 1.0 will be used.

七、参考文献

[1]. GeniE User Documentation

[2]. GeniE/Tutorials in Basics and Code Checking

[3]. GeniE/Tutorials Advanced Modelling

[4]. 关于风机 叶片/荷载/控制 方面的介绍请访问：https://www.zhihu.com/column/c_1485646874003058688

[5]. 关于风机 有限元分析 方面的介绍请访问：GeniE 实用教程（三）属性

[6]. 联系作者 ，Email： liyang@alu.hit.edu.cn

[7]. 联系作者 ，WeChat/Weixin： 761358045