本文選題：鮮棗　切入點(diǎn)：壓縮特性　出處：《甘肅農(nóng)業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鮮棗屬固體粘彈性農(nóng)業(yè)物料,其在流通鏈各環(huán)節(jié)中難免會(huì)受到不同形式載荷作用(如擠壓、碰撞、搓擦、振動(dòng)等)而造成機(jī)械損傷。本研究為預(yù)測(cè)鮮棗在收獲、貯運(yùn)、加工等過程中的機(jī)械損傷及在特定狀態(tài)(常變量、定載荷)下的機(jī)械響應(yīng),對(duì)甘肅省少雨干旱地區(qū)最有可能規(guī)�；N植的4種優(yōu)良鮮食和加工兼用型棗品種進(jìn)行整果壓縮、應(yīng)力松弛及蠕變?cè)囼?yàn)研究。獲得了5種工況下的試驗(yàn)曲線,闡明了各試驗(yàn)因素與結(jié)果間的相關(guān)關(guān)系。通過試驗(yàn)結(jié)果建立了鮮棗流變學(xué)模型及其本構(gòu)方程,并運(yùn)用有限元和虛擬樣機(jī)的方法對(duì)壓縮和應(yīng)力松弛試驗(yàn)歷程進(jìn)行了數(shù)值模擬分析,拓寬了農(nóng)業(yè)物料力學(xué)的研究范圍。研究結(jié)果可為鮮棗包裝、運(yùn)輸、加工、貯藏等環(huán)節(jié)的工程分析、品質(zhì)評(píng)價(jià)及相關(guān)作業(yè)裝備設(shè)計(jì)提供科學(xué)依據(jù),并為深入了解鮮棗結(jié)構(gòu)、改進(jìn)鮮棗加工中的質(zhì)量控制及減少棗果機(jī)械損傷提供理論依據(jù)。(1)對(duì)4種甘肅特產(chǎn)鮮棗(靖遠(yuǎn)小口大棗、臨澤小棗、敦煌鳴山大棗、蘭州壇壇棗)在5種加載速率下進(jìn)行橫向和縱向上的壓縮力學(xué)特性試驗(yàn)研究。獲得相應(yīng)的力-變形曲線,得到各鮮棗品種的彈性模量、剛度、破壞能、破裂力及破裂相對(duì)變形量等力學(xué)參數(shù)。試驗(yàn)結(jié)果表明:各品種鮮棗橫向受壓時(shí)裂紋大多出現(xiàn)在棗果蒂部,縱向受壓時(shí)裂紋出現(xiàn)在棗果經(jīng)線的各個(gè)方向上,且開裂形態(tài)相對(duì)一致;橫向壓縮破裂力范圍227.52-342.8N,縱向壓縮時(shí)破裂力范圍276.82-383.17N;鮮棗品種對(duì)彈性模量具有極顯著影響,受壓方向和加載速率對(duì)彈性模量的影響不顯著;鮮棗橫向壓縮時(shí),破裂力與彈性模量、破壞能呈極顯著正相關(guān)(p0.01),而破壞能與彈性模量、破裂相對(duì)變形量呈顯著正相關(guān)(0.01p0.05);縱向壓縮時(shí),破裂力與破裂相對(duì)變形量、破壞能呈極顯著正相關(guān),與彈性模量呈極顯著負(fù)相關(guān)(p0.01),而彈性模量與破壞能、破裂相對(duì)變形量呈顯著負(fù)相關(guān),破壞能與破裂相對(duì)變形量呈顯著正相關(guān)(0.01p0.05)。運(yùn)用有限元法模擬鮮棗在橫縱兩方向的壓縮力學(xué)試驗(yàn)過程,結(jié)果顯示:鮮棗受壓時(shí),應(yīng)力應(yīng)變主要集中在加載點(diǎn)附近,這與試驗(yàn)結(jié)果鮮棗在壓頭加載處破裂一致;力-變形曲線試驗(yàn)值與仿真值最大偏差為11.4%。表明可以利用有限元法來模擬研究鮮棗的力學(xué)進(jìn)程,拓寬了生物力學(xué)的研究方法。(2)對(duì)4種甘肅特產(chǎn)鮮棗在2種壓縮位移(2mm、3mm)下進(jìn)行橫向和縱向應(yīng)力松弛特性試驗(yàn)研究。獲得應(yīng)力松弛特性曲線,并選取適當(dāng)?shù)乃沙跀?shù)學(xué)模型,通過SPSS數(shù)據(jù)統(tǒng)計(jì)分析軟件擬合出相應(yīng)的松弛特性參數(shù)。試驗(yàn)結(jié)果表明:各品種棗樣都具有明顯的應(yīng)力松弛現(xiàn)象,松弛應(yīng)力在松弛初始時(shí)迅速衰減,直至平衡應(yīng)力后趨于穩(wěn)定;縱向壓縮時(shí)松弛應(yīng)力任意時(shí)刻都大于橫向,且鮮棗的變形量越大,其最大松弛應(yīng)力越大,任意時(shí)刻的松弛應(yīng)力也越大,最終的平衡應(yīng)力越大;鮮棗的應(yīng)力松弛模型可用廣義Maxwell五元件模型進(jìn)行很好的模擬,相關(guān)系數(shù)達(dá)0.99以上;鮮棗品種、常變形量和加載方向?qū)λプ儚椥阅Ａ縀1、E2呈極顯著影響(p0.01),不同鮮棗品種對(duì)平衡彈性模量E0影響顯著(0.01p0.05);E0與E1、E2呈極顯著正相關(guān)(0.01p0.05),E1、E2之間呈極顯著正相關(guān)(p0.01),粘性系數(shù)?2與E1、E2、E0都呈極顯著正相關(guān)(0.01p0.05)。運(yùn)用流變學(xué)模型,從動(dòng)力學(xué)的角度模擬分析鮮棗流變過程,比較應(yīng)力-時(shí)間曲線試驗(yàn)值與模擬值,最大偏差為4.7%,表明可以利用虛擬樣機(jī)的方法來模擬研究鮮棗的流變進(jìn)程,為生物力學(xué)的研究提供了新的思路。(3)對(duì)4種甘肅特產(chǎn)鮮棗在2種定載荷(85N、115N)下進(jìn)行橫向和縱向上蠕變特性試驗(yàn)研究。獲得相應(yīng)的蠕變特性曲線,選取蠕變數(shù)學(xué)模型擬合出相應(yīng)的蠕變特性參數(shù),分析不同鮮棗品種及不同加載力下的蠕變特性,通過對(duì)整果模型參數(shù)分析,獲得鮮棗蠕變特性參數(shù)間的相關(guān)關(guān)系,試驗(yàn)結(jié)果表明:各鮮棗品種在受定載荷作用時(shí),變形-時(shí)間關(guān)系曲線的變化趨勢(shì)相同,且橫向蠕變變形量大于縱向蠕變的變形量;橫向壓縮時(shí),定載荷下鳴山大棗蠕變初始變形量最大(115N時(shí)為4.85mm,85N時(shí)為3.6mm),臨澤小棗最小,曲線最低(115N時(shí)為4.16mm,85N時(shí)為3.0mm);定載荷越大,變形量越大;Burgers模型能夠很好的模擬鮮棗的蠕變特性,SPSS擬合系數(shù)達(dá)0.99以上。鮮棗品種和加載方向?qū)λ矔r(shí)彈性E1具有極顯著影響(p0.01),各因素對(duì)延遲彈性系數(shù)E2的影響均不顯著。鮮棗品種、加載方向以及定載荷對(duì)?1、?2、T的影響均不顯著(p0.05)。瞬時(shí)彈性系數(shù)E1與延遲彈性系數(shù)E2呈極顯著正相關(guān)(p0.01)。瞬時(shí)粘性系數(shù)?1與彈性系數(shù)E1、E2呈顯著負(fù)相關(guān)(0.01p0.05)。延遲時(shí)間與T與彈性系數(shù)E1、E2呈負(fù)相關(guān),與粘性系數(shù)?1、?2呈正相關(guān),但均不顯著。
[Abstract]:Fresh jujube is solid viscoelastic material in all aspects of agriculture, circulation chain will be influenced by the effect of different load (such as extrusion, collision, rubbing vibration, etc.) caused by mechanical damage. This study for the prediction of fresh jujube in the harvest, storage, processing and other mechanical damage in the process and in particular state (often variable and constant load) under mechanical response, 4 excellent fresh and processing and jujube varieties in Gansu Province, lack of rain and drought area is most likely the large-scale planting of whole fruit compression, experimental study on stress relaxation and creep. The 5 conditions of the test curve, expounds the relationship the test factors and between the results. Through the test results of fresh jujube rheological model and the constitutive equation is established, and by using the finite element method and the virtual prototype of the compression and stress relaxation test process was simulated and analyzed, broaden the research of agricultural material mechanics Range. The research results can be used for fresh jujube processing, packaging, transportation, storage and other aspects of the project analysis, and provide scientific basis for quality evaluation and the related work equipment design, and to understand the deep structure of fresh jujube, jujube improvement in processing quality control and provide a theoretical basis for reducing the mechanical fruit damage (1) of 4. Gansu specialty jujube (Jingyuan small jujube, Linze jujube, Dunhuang Lanzhou Mingshan big jujube, jujube jar) were on the transverse and vertical compression test study on mechanical characteristics of the 5 kinds of loading rate. To obtain the corresponding force deformation curve, elastic modulus, the fresh jujube varieties are stiffness, damage, rupture rupture force and relative deformation and other mechanical parameters. The experimental results showed that all the varieties of fresh jujube transverse compression crack occurs mostly in the jujube fruit stalk, longitudinal compression crack in each direction warp fruit, and cracking form relatively uniform transverse compression; Rupture force range of 227.52-342.8N, longitudinal compression rupture stress range 276.82-383.17N; fresh jujube varieties had significant effects on the elastic modulus, compression direction and loading rate on the elastic modulus is not significant; fresh jujube lateral compression, rupture force and elastic modulus, failure energy were positively correlated (P0.01), and the destruction of energy and the elastic modulus of rupture, relative deformation was positively correlated (0.01p0.05); longitudinal compression, rupture force and rupture relative deformation, failure was significantly positive correlation, and negative correlation with elastic modulus (P0.01), while the elastic modulus and failure, rupture of relative deformation was significantly negatively related to failure can the relative deformation and rupture were positively correlated (0.01p0.05). The simulation of fresh jujube in the transverse and longitudinal direction of two by using the finite element method of mechanical testing, results showed that the fresh jujube is pressed, the stress and strain are mainly concentrated in the loading point In this, and the test results of fresh jujube rupture in head loading site; and simulation values of maximum deviation of 11.4%. showed that mechanical process can simulation of fresh jujube using the finite element method of curve deformation test force, broaden the research methods of biomechanics. (2) of the 4 Gansu specialty in 2 kinds of fresh jujube the compression displacement (2mm, 3mm) under horizontal and vertical experimental study on stress relaxation characteristics. The stress relaxation curve, and select the relaxation of a suitable mathematical model, through the SPSS data analysis software fitted relaxation properties of the corresponding parameters. The test results show: all varieties of jujube samples have obvious stress relaxation the stress relaxation phenomenon, decay rapidly in the initial relaxation, until balance stress tends to be stable; longitudinal compression stress relaxation at any time is greater than the horizontal, and the deformation of fresh jujube is bigger, the maximum stress relaxation is bigger, at any time loose The relaxation of stress is large, the final balance of greater stress; well simulate the stress relaxation model can be generalized Maxwell five element model of fresh jujube, the correlation coefficient is above 0.99; fresh jujube varieties, often deformation and loading direction on the decay modulus E1, E2 had significant effect (P0.01) effect of different varieties of fresh jujube, balance the elastic modulus of E0 significantly (0.01p0.05); E0 and E1, E2 had significantly positive correlation (0.01p0.05), E1, had a significantly positive correlation between E2 (P0.01), the viscosity coefficient of? 2 and E1, E2, E0 were positively correlated (0.01p0.05). With the rheological model, analysis of fresh jujube rheological process from the angle of dynamics simulation, comparing the stress time curve of test value and simulation value, the maximum deviation is 4.7%, the rheological process shows that method can use virtual prototyping to simulate study of fresh jujube, provides a new idea for the research of Biomechanics (3) of 4. A specialty of Gansu jujube In 2 kinds of loads (85N, 115N) experimental study on transverse and longitudinal creep properties were obtained. The creep curve corresponding to the selected creep mathematics model fitting creep parameters, analysis of the creep characteristics of different fresh jujube varieties and different loading force, through the analysis of the whole fruit to obtain the relevant model parameters. The relationship between the creep parameters of fresh jujube, the test results showed that the fresh jujube varieties under constant load, the change trend of deformation time curve, deformation and lateral creep deformation is larger than the longitudinal creep; transverse compression, constant load creep deformation under initial Mingshan Dazao (115N for maximum 4.85mm, 85N 3.6mm), Linze jujube (115N minimum, the minimum curve for 4.16mm, 85N 3.0mm); constant load is larger, the greater the deformation; the Burgers model can simulate the creep characteristics of fresh jujube is very good, SPSS fitting coefficient More than 0.99 varieties of fresh jujube. And the loading direction has significant effect on the instantaneous elastic E1 (P0.01), the influences of various factors on the delayed elastic coefficient E2 were not significant. The fresh jujube varieties, loading direction and constant load of? 1, 2? T, the effect was not significant (P0.05). The instantaneous elastic system the number of E1 and delayed elastic coefficient E2 showed significant positive correlation (P0.01). The transient viscosity coefficient and the coefficient of elasticity of E1? 1, E2 showed a significant negative correlation (0.01p0.05). The delay time and the coefficient of elasticity of E1 and T, E2 was negatively correlated with the viscosity coefficient of 1? 2,? Positively correlated, but not significantly.

【學(xué)位授予單位】：甘肅農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S665.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王偉;楊紅英;黃新成;胡蕓莎;熊英;;紅棗果肉力學(xué)特性試驗(yàn)研究[J];江蘇農(nóng)業(yè)科學(xué);2015年06期

2 楊玲;張彩霞;康國棟;田義;叢佩華;;‘華紅’蘋果果肉的流變特性及其主成分分析[J];中國農(nóng)業(yè)科學(xué);2015年12期

3 范繼春;;基于Adams的馬鈴薯應(yīng)力松弛仿真模型建立及驗(yàn)證[J];中國農(nóng)機(jī)化學(xué)報(bào);2014年06期

4 王永剛;馬燕林;劉曉風(fēng);王曉力;王玉麗;任海偉;冷非凡;;小口大棗營養(yǎng)成分分析與評(píng)價(jià)[J];現(xiàn)代食品科技;2014年10期

5 王維;賀功民;王亞妮;;核桃的力學(xué)特性及有限元分析[J];中國農(nóng)機(jī)化學(xué)報(bào);2013年06期

6 付威;何榮;坎雜;張慧明;王麗紅;楊紅英;孫雨;;紅棗力學(xué)特性的試驗(yàn)研究[J];石河子大學(xué)學(xué)報(bào)(自然科學(xué)版);2013年04期

7 代治國;戴飛;蘇宏煜;王麗娟;楊國軍;張鋒偉;;豌豆擠壓力學(xué)特性試驗(yàn)及有限元分析[J];甘肅農(nóng)業(yè)大學(xué)學(xué)報(bào);2013年04期

8 周禹含;畢金峰;陳芹芹;劉璇;吳昕燁;陳瑞娟;邵春霖;;中國紅棗加工及產(chǎn)業(yè)發(fā)展現(xiàn)狀[J];食品與機(jī)械;2013年04期

9 白欣欣;劉繼展;李萍萍;;有限元法在農(nóng)業(yè)物料力學(xué)研究中的應(yīng)用進(jìn)展[J];農(nóng)機(jī)化研究;2013年02期

10 蘇卿;周志欽;;采后因素對(duì)果蔬產(chǎn)品營養(yǎng)和質(zhì)量安全的影響研究現(xiàn)狀[J];食品工業(yè)科技;2012年19期

相關(guān)博士學(xué)位論文 前3條

1 郭文斌;馬鈴薯壓縮、應(yīng)力松弛特性與淀粉含量相關(guān)性的研究[D];內(nèi)蒙古農(nóng)業(yè)大學(xué);2009年

2 王芳;西瓜壓縮及蠕變特性的研究[D];內(nèi)蒙古農(nóng)業(yè)大學(xué);2008年

3 王俊;梨桃各向流變特性及動(dòng)態(tài)特性的研究[D];東北農(nóng)業(yè)大學(xué);2001年

相關(guān)碩士學(xué)位論文 前6條

1 陶雪英;新疆紅棗競(jìng)爭(zhēng)力分析[D];新疆農(nóng)業(yè)大學(xué);2013年

2 石林榕;馬鈴薯力學(xué)特性與挖掘鏟減阻機(jī)理研究[D];甘肅農(nóng)業(yè)大學(xué);2013年

3 藏楠;馬鈴薯蠕變特性的研究與仿真[D];內(nèi)蒙古農(nóng)業(yè)大學(xué);2006年

4 梁鴻;中國紅棗及紅棗產(chǎn)業(yè)的發(fā)展現(xiàn)狀、存在問題和對(duì)策的研究[D];陜西師范大學(xué);2006年

5 劉春香;馬鈴薯塊莖外形與力學(xué)流變學(xué)性質(zhì)研究與應(yīng)用[D];東北農(nóng)業(yè)大學(xué);2006年

6 楊雪銀;基于有限元方法的板栗破殼機(jī)理的研究[D];華中農(nóng)業(yè)大學(xué);2005年

，

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