【作者】 任奕林；

【导师】 文友先；

【作者基本信息】 华中农业大学 ， 农产品加工及贮藏工程， 2007， 博士

【摘要】 鸡蛋在进入消费市场之前，必须经过分级、包装和检验环节，已经成为不可避免的趋势。但目前，鸡蛋所采用的分级方法比较单一，难以满足不同的市场需求。鸡蛋在采集、加工、运输、流通过程中，极易破损。为了确保生产、加工、设计的合理性，就必须深入研究鸡蛋的力学性能和破损机理，对蛋的承载力和抗冲击能力进行有效的定量分析。本文将鸡蛋的力学特性与外形指标联系起来，一方面有利于了解鸡蛋的物理特性及其变化规律，用力学特性来指导鸡蛋检测分级，完善鸡蛋品质评价体系；另一方面可更加深入分析鸡蛋的受力情况，进一步揭示鸡蛋的破损机理，从而为鸡蛋的采集、分级、加工、运输、流通过程提供一定的理论指导。本文在充分了解国内外物料物理特性及力学特性的相关研究的基础上，重点研究了鸡蛋各方面的特性，提出了鸡蛋分级的新方法，即从其两端对称度、与椭球体的匹配度、关键点的曲率变化等外形特征进行分级；在学习了国内外图像处理技术和软件编程技术的基础上，利用VC++编制了应用程序软件，运用多种算法完成了对鸡蛋型心、长短径、蛋截面积、对称度、匹配度、关键点曲率半径的检测。在此过程中首次采用了ASM方法进行鸡蛋的检测，并提出了许多新的算法来进行鸡蛋的图像处理，如直角坐标算法、鸡蛋中心的搜索算法及鸡蛋的灰度匹配法；确定了研究鸡蛋力学特性的试验方案，即选择加载方向、加载位置、加载速度、鸡蛋新鲜度、对称度、匹配度、蛋重、蛋型指数、关键点曲率半径值等作为试验因素，在万能材料试验机上分别测得鸡蛋破裂时的最大抗载。并在此基础上，以对称度、匹配度、蛋型指数、关键点曲率半径值等因素安排正交试验，对各因素与测量指标之间的关系进行了系统全面的分析，这也是鲜少有前人做过的研究。最后，利用有限元分析软件ANSYS对在各种施力状态下鸡蛋的应力应变进行了仿真分析。研究结果表明，利用本课题所搭建的机器视觉系统，对鸡蛋图像进行处理后采用直角坐标检测算法，检测到的边缘较好地保持了原图的边缘线；利用ASM方法检测鸡蛋匹配度，具有快速、准确、方便的特点。鸡蛋的匹配度符合正态分布，82.24％的鸡蛋外形与椭球体的接近程度都大于95％。其匹配度与长短径、蛋型指数及蛋重的相关性均不显著；92.93％的鸡蛋其两端的对称度都达到了92.22％，对称度与长径、蛋型指数、蛋内像素和三个因素之间的关系较为显著，而与蛋重、短径、匹配度之间的关系不显著。进一步通过曲率分布规律说明了鸡蛋形状关于其长轴基本对称，但关于短轴不对称。分析了鸡蛋各关键点曲率半径之间的关系。鸡蛋的大头顶点曲率半径与蛋型指数关系极显著，与蛋的两端对称度和蛋内像素和的关系较显著，但与匹配度的关系不显著。鸡蛋的小头顶点曲率半径与蛋型指数、两端对称度之间关系极显著，与蛋内像素和、匹配度的关系不显著。鸡蛋的中间点曲率半径大小与蛋型指数和蛋内像素和关系极显著，与蛋的两端对称度及匹配度的关系不显著。加载方向、加载位置、加载速度、鸡蛋新鲜度、对称度、匹配度、蛋型指数、关键点曲率半径值等对鸡蛋最大抗载有显著影响，而蛋重对最大抗载影响不大。按其影响主次因素依次为：对称度、蛋形指数、对称度与曲率的交互项、曲率、蛋型指数与曲率的交互项、匹配度、对称度与匹配度的交互项、匹配度与蛋型指数的交互项。有限元仿真结果表明，鸡蛋在长轴方向承载时所产生的应力比短轴方向要小，蛋型指数对应力有一定的影响，此结果与在万能试验机上试验结果相一致，可以为鸡蛋生产、运输及加工设备的设计提供参考依据。更多还原

【Abstract】 It’s an inevitable trend that eggs must be sorted, packed and inspectedbefore they enter into the market. Now, it’s difficult to meet the differentdemand because of single method of grading eggs. Eggs are easy to be broken duringthe process of collecting, processing, transporting and circulation. It’stherefore, necessary to intensively study egg’s biomechanics and quantitativeanalysis egg’s load capacity to ensure the reliability and rationality ofprocessing and design. In this article, the biomechanics and shape indicatorsof eggs are combined, one hand, it’s favorable to understand egg’s mechanics andits laws, to guide eggs grading with mechanical properties, to improve theevaluation system of egg’s quality. On the other hand, since egg’s mechanics aremore intensively researched and broken mechanism was revealed, which can conductegg’s sorting, collecting and transporting.According to the understanding of inland and oversea documents on materielcharacteristics and mechanical properties, especially eggs characteristics, newmethods of eggs grading were carried out, that is, taking symmetrical degreebetween two extremes, matching degree to ellipsoidal, Curvature of importantpoints to grade eggs. Based on the learning of image processing technology andprogramming technique, a software were produced to inspect long radium, shortradium, symmetrical degree between two extremes, matching degree to ellipsoidal,curvature of important points of eggs. ASM method was used in this process thefirst time. A experiment plan was determined, that is, taking loading director,loading velocity, loading points, egg’ s fresh, egg’ s weight, shape index,symmetrical degree between two extremes, matching degree to ellipsoidal,curvature of important points as factors and rupture force as indexes. Afterthese experiments, An orthogonal experiment was designed, the relationshipbetween every factor and index was analyzed. On the base of the above researches, the stress and train distributions of eggshell are analyzed through ANSYSsoftware.The results show that the old image’ s edge curves were perfectly kept afterimage processing through the computer vision system in this research.It’ s very fast, accurate, convenient to test matching degree to ellipsoidalwith ASM, the degree state a normal distribution and which of 82.24% eggsoverweighs 95%. The degree has little correlation with long radium, short radium,shape index and weigh. The symmetrical degree between two extremes of 92.93%eggs attend to 92.22%, which has noticeable relations with long radium, shapeindex, area and hasn’t noticeable relationship with weight, short radium andmatching degree to ellipsoidal.Some factors such as loading director, loading velocity, loading points,egg’ s fresh, shape index, symmetrical degree, matching degree, curvature ofimportant points have notable impact on counteracting load except egg’ s weight,the influence order is: symmetrical degree, shape index, interaction betweensymmetrical degree and curvature, curvature, interaction between shape indexand curvature, matching degree.The results of FEA show that the stress along long axis is smaller than alongshort axis ,egg shape index has great impact on the stress when loaded. Thesimulating result was in accord with the result of experiments, so it can conductegg’ s produce, transporting and designing of eggs processing equipments.更多还原