某型机电包装箱静动态力学性能分析及结构优化

发布时间：2018-07-26 16:25

【摘要】：当前机电包装箱的主要材料是森林原木，而我国是一个森林资源极为匮乏的国家，每年仅用于包装的木材就占商品材总量的1/6左右，因此，以新型材料如单板层积材（LVL）等替代原木用于机电产品的包装对缓解我国森林资源缺乏的矛盾有着十分重要的意义。同时，由于机电产品对精度与可靠性的要求非常高，这需要其包装箱在运输和周转的过程中具有良好的力学性能，因而必须对机电包装箱的力学性能进行研究。本文通过对南京某公司某型机电产品包装箱进行实际测绘后，基于大型三维建模软件Pro/ENGINEER创建了包装箱的几何模型，并利用经典力学理论与基于ANSYS的有限元仿真两种计算方法分别对松木与杨木LVL两种材料的包装箱结构静态力学性能进行了详细分析，通过对比分析发现：基于ANSYS的有限元分析结果与经典力学理论分析结果相吻合，两者之间的相对误差非常小，最大误差为12.189%，最小误差仅为0.102%；杨木LVL包装箱的力学性能完全符合机电包装箱实际使用的要求，因此，，杨木LVL完全可以替代松木等原木作为机电包装材料。此外，本文通过对现有包装箱结构进行模态分析，得到了包装箱结构的固有频率与相应的模态振型，为包装箱在振动、冲击等后续工况下的力学性能分析提供了一定的基础，通过模态分析可发现：包装箱的前十阶固有频率均小于30Hz，而包装箱在运输和周转的过程中通常受到的外部激励频率一般小于25Hz，容易在外部激励的作用下发生共振，因而对包装箱进行模态分析研究是十分必要的，在必要的时候需采取适当的措施避免包装箱结构与外部激励发生共振。最后，本文对现有包装箱的底架枕木与纵梁进行了优化设计。优化分析前底架枕木的截面宽度、截面高度、最大挠度与总体积分别为0.120m、0.020m、4.441×10-3m与3.504×10-3m3，优化后枕木的截面宽度、截面高度、最大挠度与总体积分别为0.044m、0.032m、3.086×10-3m与2.065×10-3m3，尽管优化后枕木的截面高度尺寸比优化前增加了60%，但优化后枕木的截面宽度尺寸、最大挠度以及总体积分别比优化前减小了63.333%、30.511%与41.067%；优化前底架纵梁的截面宽度、截面高度、最大挠度与总体积分别为0.170m、0.150m、3.389×10-3m与0.127m3，优化后纵梁的截面宽度、截面高度、最大挠度与总体积分别为0.148m、0.158m、3.370×10-3m与0.116m3，尽管优化后纵梁的截面高度尺寸比优化前增加了5.333%，但优化后纵梁的截面宽度尺寸、最大挠度以及总体积分别比优化前减少了12.941%、0.561%与8.661%。通过对比分析优化前后底架枕木（或纵梁）的力学性能可知：合理减小包装箱底架枕木（或纵梁）的截面宽度尺寸，同时适当增加其截面高度尺寸，可以使包装箱底架枕木（或纵梁）在满足使用性能要求的同时，降低木材的使用量。
[Abstract]:At present, the main material used in mechatronic packing cases is forest logs. However, China is a country with extremely scarce forest resources. The timber used for packaging alone accounts for about 1 / 6 of the total commercial timber every year. Therefore, It is of great significance to replace log packaging with new materials such as veneer laminated material (LVL) in order to alleviate the contradiction of forest resources shortage in China. At the same time, the mechanical properties of mechatronic products must be studied because of the very high requirement of precision and reliability, which requires that the packing cases have good mechanical properties in the course of transportation and turnover. After surveying and mapping a certain type of mechanical and electrical product packing box in a Nanjing company, the geometric model of the packing box is established based on the large-scale 3D modeling software Pro/ENGINEER. The static mechanical properties of the packing box structure of pine and poplar LVL are analyzed in detail by using the classical mechanics theory and the finite element simulation method based on ANSYS. It is found that the results of finite element analysis based on ANSYS are consistent with those of classical mechanics theory. The relative error between them is very small, the maximum error is 12.189 and the minimum error is only 0.102. The mechanical properties of poplar LVL packing box fully meet the requirements of mechanical and electrical packaging. Therefore, poplar LVL can completely replace pine and other logs as mechanical and electrical packaging materials. In addition, through modal analysis of the existing packing box structure, the natural frequency and the corresponding modal mode of the packaging structure are obtained, which provides a certain basis for the mechanical performance analysis of the packaging box under the following working conditions, such as vibration and impact. Modal analysis shows that the first ten natural frequencies of packing cases are all less than 30 Hz, while the external excitation frequencies of packing cases are generally less than 25 Hz in the course of transportation and turnover, which is easy to resonate under external excitation. Therefore, it is very necessary to study the modal analysis of the packing box. When necessary, appropriate measures should be taken to avoid the resonance between the packing box structure and the external excitation. Finally, this paper optimizes the design of the underrest and longitudinal beam of the existing packing box. The cross-section width, cross-section height, maximum deflection and total volume of the front bottom sleeper are 0.120 m ~ (0.020) m ~ (-3) and 3.504 脳 10 ~ (-3) m ~ (-3), respectively. The cross-section width and section height of the sleeper are optimized. The maximum deflection and the total volume are 0.044 m / m 0.032 mN 3.086 脳 10 ~ (-3) m and 2.065 脳 10 ~ (-3) m ~ (-3) respectively. Although the cross-section height dimension of the optimized sleepers is increased by 60%, the cross-section width dimension, the maximum deflection and the total volume of the optimized sleepers are reduced by 63.33330.511% and 41.067%, respectively. The cross-section width, cross-section height, maximum deflection and total volume of the longitudinal beam of the front underframe are 0.170 mg / m 0.150 mU 3.389 脳 10 ~ (-3) and 0.127 m ~ (3) respectively. After optimization, the cross-section width and cross-section height of the optimized longitudinal beam are obtained. The maximum deflection and total volume are 0.148mg / m 0.158m/ m and 0.116m3respectively. Although the cross-section height dimension of the optimized longitudinal beam increases by 5.333than that before the optimization, the cross-section width dimension, maximum deflection and total volume of the optimized longitudinal beam are reduced by 12.941% and 8.661wt%, respectively. By comparing and analyzing the mechanical properties of the underrest (or longitudinal beam) before and after optimization, it can be seen that the cross-section width of the bottom sleeper (or longitudinal beam) of the packing box can be reduced reasonably, and the cross-section height dimension of the sleeper (or the longitudinal beam) should be increased appropriately at the same time. Can make box chassis sleeper (or longitudinal beam) to meet the performance requirements, while reducing the use of wood.
【学位授予单位】：南京林业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB487

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