大型船体结构焊接变形.doc
约95页DOC格式手机打开展开
大型船体结构焊接变形,摘要众所周知，焊接技术在现代船舶工业中的地位变得越来越重要，焊接技术水平对提高船舶焊接生产效率、缩短船舶建造周期、降低成本、提高企业竞争力具有举足轻重的作用。而在焊接过程中焊接变形不但备受重视而且又是难以控制的环节。焊接变形造成焊件形状尺寸改变，当受到工作载荷作用时，焊接变形产生的附加弯矩和应力集中现象是造成船舶结构早...
内容介绍
此文档由会员 违规屏蔽12 发布
摘要
众所周知，焊接技术在现代船舶工业中的地位变得越来越重要，焊接技术水平对提高船舶焊接生产效率、缩短船舶建造周期、降低成本、提高企业竞争力具有举足轻重的作用。而在焊接过程中焊接变形不但备受重视而且又是难以控制的环节。焊接变形造成焊件形状尺寸改变，当受到工作载荷作用时，焊接变形产生的附加弯矩和应力集中现象是造成船舶结构早期失效的主要原因。因此，预测及控制焊接变形已经是实际生产中必须要解决的问题。
预测大型复杂焊接结构的焊接变形必须解决两个问题。其一是要保证足够的预测精度，其二是要节约运算时间和成本。焊接热弹塑性有限元法在焊接数值模拟中得到广泛应用。但它需要的计算时间长、计算规模大，目前只适用于焊接接头及较小结构的焊接行为力学分析，因而用于预测大型复杂结构焊接变形时还有限。
本文采用日本学者提出的残余应力之源的固有应变的理论，开展大型复杂船体结构的焊接变形预测研究工作。固有应变法是一种相对快速的、有效的、近似的方法，并能够得到一定准确度的焊接变形值，为确定反变形量提供一种有力的、新的计算工具。这种方法具有非常大的工程实用意义和发展前景。需要注意的是，固有应变法是建立在船体结构焊接的固有应变数据库基础之上，固有应变数据库是确保预测焊接变形结果准确的前提。
本文算例采用基于固有应变预测法和弹性板单元有限元法，利用焊接结构变形专用预测软件Weld_sta对研究对象进行焊接变形模拟计算，预测其焊接变形。固有应变预测法是在大量的计算和实测数据基础上，整理得到简化的以板厚为参数的固有应变计算公式，并建立船体结构焊接的固有应变数据库，为预测大型复杂船体结构的焊接变形提供可能。
研究结果表明，基于固有应变法的专用焊接软件Weld_sta可以成功预测大型复杂船体结构的焊接变形，为确定反变形量和精度造船的实现提供一种新计算工具，为预测大型复杂结构的焊接变形提供一种新的思路和方法。
通过以上的工作基本实现了大型复杂船体结构焊接变形的预测模拟，由于焊接过程的复杂性，考虑影响焊接变形的因素不够全面，还存在一定的差距，仍然需要进行深入的研究。
关键词：固有应变理论；Weld_sta软件；曲板结构；大型复杂船体结构；焊接变形
Abstract
It is well known that welding technology is playing a more and more important role in ship industry, which can improve productive efficiency in welding of ship, shorten the production cycle, reduce cost and enhance the competitiveness of enterprise. Welding distortion, however, not only has been taken into consideration. But also it is tough to control the welding distortion in the whole welding procedure. Welding distortion existed may lead to shape and size of the ship structure to vary, what’s more, the additional bending moment and phenomenon of stress concentration which were generated by welding distortion under working load is the main reason leading to the premature failure of hull structure. For the reason above mentioned, the prediction and control of welding distortion has been a significant and emergent problem to be resolved in actual production.
There are two problems in predicting welding distortion of large and complicated ship structure. One is how to ensure enough distortion tolerance; another is how to save calculation time and cost. Thermal elastic-plastic finite element method is widely used in numerical simulation of welding, which needs computer memory of large capacity and takes more time to calculate and now is not applicable to research of other large-scale and complicated structures apart from welded joint and small structures.
The paper adopted the inherent strain theory that Japanese scholars brought forward and studied the prediction of the distortion of the large and complicated ship structure on the basic of inherent strain theory. Inherent strain method is a kind of relatively fast and effective and approximate method, what’s more, it can make sure to get values of welding distortion accurately, which offers a strong and new tool in calculating values of anti-deformation. Hence, this method must be really very important in practical significance and be with pretty good future.
This paper takes the seven examples as object, those examples adopted inherent strain method and finite element method of plastic shell element. Then, numerical simulating the welding distortion of ship structures by special software Weld_sta. In the method on the basic of inherent strain theory, getting a simplified formula is about a thickness parameter of plates through a pretty large number of calculating and measuring datas and establishing an inherent strain database of ship structures welding. It is pretty possible to predict the welding distortion of large hull structure on the basic of above mentioned.
The study shows that the exclusive welding software Weld_sta on the basic of inherent strain successfully predict welding distortion of hull structure, which provides a powerful and new tool for confirming value of anti-deformation and accuracy shipbuilding to achieve, providing a kind of new idea and method for predicting the welding distortion of large-scale and complicated structure.
Though the inherent strain finite element method can predict successfully the ..
众所周知，焊接技术在现代船舶工业中的地位变得越来越重要，焊接技术水平对提高船舶焊接生产效率、缩短船舶建造周期、降低成本、提高企业竞争力具有举足轻重的作用。而在焊接过程中焊接变形不但备受重视而且又是难以控制的环节。焊接变形造成焊件形状尺寸改变，当受到工作载荷作用时，焊接变形产生的附加弯矩和应力集中现象是造成船舶结构早期失效的主要原因。因此，预测及控制焊接变形已经是实际生产中必须要解决的问题。
预测大型复杂焊接结构的焊接变形必须解决两个问题。其一是要保证足够的预测精度，其二是要节约运算时间和成本。焊接热弹塑性有限元法在焊接数值模拟中得到广泛应用。但它需要的计算时间长、计算规模大，目前只适用于焊接接头及较小结构的焊接行为力学分析，因而用于预测大型复杂结构焊接变形时还有限。
本文采用日本学者提出的残余应力之源的固有应变的理论，开展大型复杂船体结构的焊接变形预测研究工作。固有应变法是一种相对快速的、有效的、近似的方法，并能够得到一定准确度的焊接变形值，为确定反变形量提供一种有力的、新的计算工具。这种方法具有非常大的工程实用意义和发展前景。需要注意的是，固有应变法是建立在船体结构焊接的固有应变数据库基础之上，固有应变数据库是确保预测焊接变形结果准确的前提。
本文算例采用基于固有应变预测法和弹性板单元有限元法，利用焊接结构变形专用预测软件Weld_sta对研究对象进行焊接变形模拟计算，预测其焊接变形。固有应变预测法是在大量的计算和实测数据基础上，整理得到简化的以板厚为参数的固有应变计算公式，并建立船体结构焊接的固有应变数据库，为预测大型复杂船体结构的焊接变形提供可能。
研究结果表明，基于固有应变法的专用焊接软件Weld_sta可以成功预测大型复杂船体结构的焊接变形，为确定反变形量和精度造船的实现提供一种新计算工具，为预测大型复杂结构的焊接变形提供一种新的思路和方法。
通过以上的工作基本实现了大型复杂船体结构焊接变形的预测模拟，由于焊接过程的复杂性，考虑影响焊接变形的因素不够全面，还存在一定的差距，仍然需要进行深入的研究。
关键词：固有应变理论；Weld_sta软件；曲板结构；大型复杂船体结构；焊接变形
Abstract
It is well known that welding technology is playing a more and more important role in ship industry, which can improve productive efficiency in welding of ship, shorten the production cycle, reduce cost and enhance the competitiveness of enterprise. Welding distortion, however, not only has been taken into consideration. But also it is tough to control the welding distortion in the whole welding procedure. Welding distortion existed may lead to shape and size of the ship structure to vary, what’s more, the additional bending moment and phenomenon of stress concentration which were generated by welding distortion under working load is the main reason leading to the premature failure of hull structure. For the reason above mentioned, the prediction and control of welding distortion has been a significant and emergent problem to be resolved in actual production.
There are two problems in predicting welding distortion of large and complicated ship structure. One is how to ensure enough distortion tolerance; another is how to save calculation time and cost. Thermal elastic-plastic finite element method is widely used in numerical simulation of welding, which needs computer memory of large capacity and takes more time to calculate and now is not applicable to research of other large-scale and complicated structures apart from welded joint and small structures.
The paper adopted the inherent strain theory that Japanese scholars brought forward and studied the prediction of the distortion of the large and complicated ship structure on the basic of inherent strain theory. Inherent strain method is a kind of relatively fast and effective and approximate method, what’s more, it can make sure to get values of welding distortion accurately, which offers a strong and new tool in calculating values of anti-deformation. Hence, this method must be really very important in practical significance and be with pretty good future.
This paper takes the seven examples as object, those examples adopted inherent strain method and finite element method of plastic shell element. Then, numerical simulating the welding distortion of ship structures by special software Weld_sta. In the method on the basic of inherent strain theory, getting a simplified formula is about a thickness parameter of plates through a pretty large number of calculating and measuring datas and establishing an inherent strain database of ship structures welding. It is pretty possible to predict the welding distortion of large hull structure on the basic of above mentioned.
The study shows that the exclusive welding software Weld_sta on the basic of inherent strain successfully predict welding distortion of hull structure, which provides a powerful and new tool for confirming value of anti-deformation and accuracy shipbuilding to achieve, providing a kind of new idea and method for predicting the welding distortion of large-scale and complicated structure.
Though the inherent strain finite element method can predict successfully the ..
