《機械設(shè)計》課件

《機械設(shè)計》PPT課件本課件僅供大家學(xué)習學(xué)習學(xué)習完畢請自覺刪除謝謝本課件僅供大家學(xué)習學(xué)習學(xué)習完畢請自覺刪除謝謝《機械設(shè)計》PPT課件本課件僅供大家學(xué)習學(xué)習材料不同，應(yīng)力集中的敏感性不同。強度極限愈高的鋼材，應(yīng)力集中越敏感，鑄鐵則遲鈍很多。常用有效應(yīng)力集中系數(shù)kσ、kτ來考慮應(yīng)力集中對疲勞強度的影響。理論應(yīng)力集中系數(shù)材料的敏感系數(shù)附表3-1附表3-2附表3-3附圖3-1

注意：若在同一截面上同時有幾個應(yīng)力集中源時，應(yīng)采用其中最大有效應(yīng)力集中系數(shù)進行計算。附表3-4、3-5附表3-6、3-7其它應(yīng)力集中系數(shù)見材料不同，應(yīng)力集中的敏感性不同。強度極限愈高二、尺寸效應(yīng)零件尺寸越大，疲勞強度越低，稱為尺寸效應(yīng)。其原因是因為尺寸大時，材料晶粒粗，出現(xiàn)缺陷的概率多，機加工后表面冷作硬化層相對較薄，疲勞裂紋容易形成。對于受彎曲和轉(zhuǎn)矩的零件，疲勞強度隨尺寸增大而降低的現(xiàn)象還與零件截面上承受非均勻分布的應(yīng)力剃度有關(guān)，如右圖所示。顯然，直徑較大的試件更容易發(fā)生破壞。二、尺寸效應(yīng)零件尺寸越大，疲勞強度越低，稱為尺寸系數(shù)愈小表示疲勞強度降低愈大。通常用、表示零件的尺寸系數(shù)。附圖3-3附圖3-2螺紋聯(lián)接件的尺寸系數(shù)（因截面為圓形，故只有尺寸影響）見下表：0.500.520.540.570.600.630.680.710.760.81180726456484032282420≤16直徑d/mm對于輪轂或滾動軸承與軸以過盈配合相聯(lián)接時，可按求出其有效應(yīng)力集中系數(shù)與尺寸系數(shù)的比值。如缺乏試驗數(shù)據(jù)，設(shè)計時可取。附表3-8尺寸系數(shù)愈小表示疲勞強度降低愈大。通常用三、表面狀態(tài)的影響零件表面質(zhì)量（主要指表面粗糙度，表面粗糙度參數(shù)值越小疲勞強度越高）對疲勞強度的影響，通常用、表示表面狀態(tài)的影響程度。1、表面質(zhì)量附圖3-42、表面處理表面處理對疲勞強度影響用強化系數(shù)表示。附表3-9附表3-10附表3-11三、表面狀態(tài)的影響零件表面質(zhì)量（主要指表面粗則零件的極限應(yīng)力圖為：綜合考慮上述三個主要方面，則可獲得綜合影響系數(shù)Kσ：ADGCO●●●●則零件的極限應(yīng)力圖為：綜合考慮上述三個主要方面，則可獲得綜合簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉伸r/dD/d∞2.001.501.301.201.101.051.031.021.010.042.702.372.151.941.700.102.452.392.332.272.182.011.811.681.581.420.152.082.041.991.951.901.781.641.551.471.330.201.861.831.801.771.731.651.541.461.401.280.251.721.691.671.651.621.551.461.401.341.240.301.611.591.581.551.531.471.401.361.311.22Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回下一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎曲r/dD/d∞2.001.501.301.201.101.051.031.021.010.042.832.792.742.702.612.452.222.021.881.660.101.991.981.961.921.891.811.701.611.531.410.151.751.741.721.701.691.631.561.491.421.330.201.611.591.581.571.561.511.461.401.341.270.251.491.481.471.461.451.421.381.341.291.230.301.411.411.401.391.381.361.331.291.241.21Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回下一頁上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭轉(zhuǎn)剪切r/dD/d∞2.001.301.201.101.051.021.010.041.971.931.891.851.741.611.451.330.101.521.511.481.461.411.351.271.200.151.391.381.371.351.321.271.211.160.201.321.311.301.281.261.221.181.140.251.271.261.251.241.221.191.161.130.301.221.221.211.201.191.171.151.12Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉伸r/dD/d2.001.501.301.201.151.101.071.051.021.010.042.802.572.392.282.141.991.921.821.561.420.101.991.891.791.691.631.561.521.461.331.230.151.771.681.591.531.481.441.401.361.261.180.201.631.561.491.441.401.371.331.311.221.150.251.541.491.431.371.341.311.291.271.201.130.301.471.431.391.331.301.281.261.241.191.12附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr返回下一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎曲r/dD/d6.03.02.01.501.201.101.051.031.021.010.042.592.402.332.212.092.001.881.801.721.610.101.881.801.731.681.621.591.531.491.441.360.151.641.591.551.521.481.461.421.381.341.260.201.491.461.441.421.391.381.341.311.271.200.251.391.371.351.341.331.311.291.271.221.170.301.321.311.301.291.271.261.251.231.201.14附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr下一頁上一頁返回簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭轉(zhuǎn)剪切r/dD/d2.01.331.201.090.041.841.791.661.320.101.461.411.331.170.151.341.291.231.130.201.261.231.171.110.251.211.181.141.090.301.181.161.121.09附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr返回上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭r/

d/D0.00.050.100.150.200.250.30d/D0.00.050.100.150.200.250.303.02.462.252.132.031.961.892.01.781.661.571.501.461.42附表3-3軸上橫向孔處的理論集中系數(shù)DdMMDdTT公稱扭轉(zhuǎn)應(yīng)力公稱彎曲應(yīng)力返回d/D0.00.050.100.150.200.1.75●●●0.88查表過程返回1.75●●●0.88查表過程返回返回返回返回返回拋光磨削精車粗車未加工400600800100012000.20.40.60.8附圖3-4鋼材的表面質(zhì)量系數(shù)返回拋光磨削精車粗車未加工400600800100012000.直徑/mm配合σB/MPa4005006007008009001000120030H7/r62.252.502.753.003.253.503.754.25H7/k61.691.882.062.252.442.632.823.19H7/h61.461.631.791.952.112.282.442.7650H7/r62.753.053.363.663.964.284.605.20H7/k62.062.282.522.762.973.203.453.90H7/h61.801.982.182.382.572.783.003.40>100H7/r62.953.283.603.944.254.604.905.60H7/k62.222.462.702.963.203.463.984.20H7/h61.922.132.342.562.763.003.183.46注：⑴滾動軸承與軸配合處的值與表內(nèi)所列H7/r6配合的值相同；⑵表中無相應(yīng)的數(shù)值時，可按插入法計算。附表3-8零件與軸過盈配合處的值返回直徑/mm配合σB/MPa40050060070080090附表3－9表面高頻淬火的強化系數(shù)βq試件種類試件直徑/mmβq無應(yīng)力集中7～201.3～1.630～401.2～1.5有應(yīng)力集中7～201.6～2.830～401.5～2.5注：表中系數(shù)值用于旋轉(zhuǎn)彎曲，淬硬層厚度為0.9～1.5。應(yīng)力集中時，強化系數(shù)較高。返回附表3－9表面高頻淬火的強化系數(shù)βq試件種類試件直徑/化學(xué)熱處理方法試件種類試件直徑/mmβq氮化，氧化層厚度0.1~0.4mm表面硬度64HRC以上無應(yīng)力集中8～151.15～1.2530～401.10～1.15有應(yīng)力集中8～151.9～3.030～401.3～2.0滲碳，滲碳層厚度0.2~0.6mm無應(yīng)力集中8～151.2～2.130～401.1～1.2有應(yīng)力集中8～151.5～2.530～401.2～2.0氧化，氰化層厚度0.2mm無應(yīng)力集中101.8附表3－10化學(xué)熱處理的強化系數(shù)βq返回化學(xué)熱處理方法試件種類試件直徑/mmβq氮化，氧化層厚度0.加工方法試件種類試件直徑/mmβq滾子滾壓無應(yīng)力集中7～101.2～1.430～401.1～1.25有應(yīng)力集中7～201.5～2..230～401.3～1.8噴丸無應(yīng)力集中7～201.1～1.330～401.1～1.2有應(yīng)力集中7～201.4～2.530～401.1～1.5附表3－11表面硬化加工的強化系數(shù)βq返回加工方法試件種類試件直徑/mmβq滾子滾壓無應(yīng)力集中7～附表3-4軸上鍵槽處的有效應(yīng)力集中系數(shù)軸材料的σB/MPa5006007007508009001000kσ1.5－－1.75－－2.0kτ－1.51.6－1.71.81.9注：公稱應(yīng)力按照扣除鍵槽的凈截面面積來求。附表3-5外花鍵的有效應(yīng)力集中系數(shù)軸材料的σB40050060070080090010001200kσ1.351.451.551.601.651.701.721.75kτ矩形齒2.102.252.362.452.552.652.702.80漸開線形齒1.401.431.461.491.521.551.581.60返回附表3-4軸上鍵槽處的有效應(yīng)力集中系數(shù)軸材料的σB/M附表3-6公稱直徑12mm的普通螺紋的拉壓力集中系數(shù)材料的σB/MPa4006008001000kτ3.03.94.85.2附表3-7螺紋聯(lián)接件的尺寸系數(shù)εσ直徑d/mm≤1620242832404856647280εσ10.810.760.710.680.630.600.570.540.520.50返回附表3-6公稱直徑12mm的普通螺紋的拉壓力集中系數(shù)材料《機械設(shè)計》PPT課件本課件僅供大家學(xué)習學(xué)習學(xué)習完畢請自覺刪除謝謝本課件僅供大家學(xué)習學(xué)習學(xué)習完畢請自覺刪除謝謝《機械設(shè)計》PPT課件本課件僅供大家學(xué)習學(xué)習材料不同，應(yīng)力集中的敏感性不同。強度極限愈高的鋼材，應(yīng)力集中越敏感，鑄鐵則遲鈍很多。常用有效應(yīng)力集中系數(shù)kσ、kτ來考慮應(yīng)力集中對疲勞強度的影響。理論應(yīng)力集中系數(shù)材料的敏感系數(shù)附表3-1附表3-2附表3-3附圖3-1

注意：若在同一截面上同時有幾個應(yīng)力集中源時，應(yīng)采用其中最大有效應(yīng)力集中系數(shù)進行計算。附表3-4、3-5附表3-6、3-7其它應(yīng)力集中系數(shù)見材料不同，應(yīng)力集中的敏感性不同。強度極限愈高二、尺寸效應(yīng)零件尺寸越大，疲勞強度越低，稱為尺寸效應(yīng)。其原因是因為尺寸大時，材料晶粒粗，出現(xiàn)缺陷的概率多，機加工后表面冷作硬化層相對較薄，疲勞裂紋容易形成。對于受彎曲和轉(zhuǎn)矩的零件，疲勞強度隨尺寸增大而降低的現(xiàn)象還與零件截面上承受非均勻分布的應(yīng)力剃度有關(guān)，如右圖所示。顯然，直徑較大的試件更容易發(fā)生破壞。二、尺寸效應(yīng)零件尺寸越大，疲勞強度越低，稱為尺寸系數(shù)愈小表示疲勞強度降低愈大。通常用、表示零件的尺寸系數(shù)。附圖3-3附圖3-2螺紋聯(lián)接件的尺寸系數(shù)（因截面為圓形，故只有尺寸影響）見下表：0.500.520.540.570.600.630.680.710.760.81180726456484032282420≤16直徑d/mm對于輪轂或滾動軸承與軸以過盈配合相聯(lián)接時，可按求出其有效應(yīng)力集中系數(shù)與尺寸系數(shù)的比值。如缺乏試驗數(shù)據(jù)，設(shè)計時可取。附表3-8尺寸系數(shù)愈小表示疲勞強度降低愈大。通常用三、表面狀態(tài)的影響零件表面質(zhì)量（主要指表面粗糙度，表面粗糙度參數(shù)值越小疲勞強度越高）對疲勞強度的影響，通常用、表示表面狀態(tài)的影響程度。1、表面質(zhì)量附圖3-42、表面處理表面處理對疲勞強度影響用強化系數(shù)表示。附表3-9附表3-10附表3-11三、表面狀態(tài)的影響零件表面質(zhì)量（主要指表面粗則零件的極限應(yīng)力圖為：綜合考慮上述三個主要方面，則可獲得綜合影響系數(shù)Kσ：ADGCO●●●●則零件的極限應(yīng)力圖為：綜合考慮上述三個主要方面，則可獲得綜合簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉伸r/dD/d∞2.001.501.301.201.101.051.031.021.010.042.702.372.151.941.700.102.452.392.332.272.182.011.811.681.581.420.152.082.041.991.951.901.781.641.551.471.330.201.861.831.801.771.731.651.541.461.401.280.251.721.691.671.651.621.551.461.401.341.240.301.611.591.581.551.531.471.401.361.311.22Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回下一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎曲r/dD/d∞2.001.501.301.201.101.051.031.021.010.042.832.792.742.702.612.452.222.021.881.660.101.991.981.961.921.891.811.701.611.531.410.151.751.741.721.701.691.631.561.491.421.330.201.611.591.581.571.561.511.461.401.341.270.251.491.481.471.461.451.421.381.341.291.230.301.411.411.401.391.381.361.331.291.241.21Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回下一頁上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭轉(zhuǎn)剪切r/dD/d∞2.001.301.201.101.051.021.010.041.971.931.891.851.741.611.451.330.101.521.511.481.461.411.351.271.200.151.391.381.371.351.321.271.211.160.201.321.311.301.281.261.221.181.140.251.271.261.251.241.221.191.161.130.301.221.221.211.201.191.171.151.12Ddr附表3-1軸上環(huán)槽處的理論應(yīng)力集中系數(shù)返回上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉伸r/dD/d2.001.501.301.201.151.101.071.051.021.010.042.802.572.392.282.141.991.921.821.561.420.101.991.891.791.691.631.561.521.461.331.230.151.771.681.591.531.481.441.401.361.261.180.201.631.561.491.441.401.371.331.311.221.150.251.541.491.431.371.341.311.291.271.201.130.301.471.431.391.331.301.281.261.241.191.12附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr返回下一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）拉r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎曲r/dD/d6.03.02.01.501.201.101.051.031.021.010.042.592.402.332.212.092.001.881.801.721.610.101.881.801.731.681.621.591.531.491.441.360.151.641.591.551.521.481.461.421.381.341.260.201.491.461.441.421.391.381.341.311.271.200.251.391.371.351.341.331.311.291.271.221.170.301.321.311.301.291.271.261.251.231.201.14附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr下一頁上一頁返回簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）彎r/簡圖應(yīng)力公稱應(yīng)力公式（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭轉(zhuǎn)剪切r/dD/d2.01.331.201.090.041.841.791.661.320.101.461.411.331.170.151.341.291.231.130.201.261.231.171.110.251.211.181.141.090.301.181.161.121.09附表3-2軸肩圓角處的理論應(yīng)力集中系數(shù)Ddr返回上一頁簡圖應(yīng)力公稱應(yīng)（拉伸、彎曲）或（扭轉(zhuǎn)剪切）扭r/

d/D0.00.050.100.150.200.250.30d/D0.00.050.100.150.200.250.303.02.462.252.132.031.961.892.01.781.661.571.501.461.42附表3-3軸上橫向孔處的理論集中系數(shù)DdMMDdTT公稱扭轉(zhuǎn)應(yīng)力公稱彎曲應(yīng)力返回d/D0.00.050.100.150.200.1.75●●●0.88查表過程返回1.75●●●0.88查表過程返回返回返回返回返回拋光磨削精車粗車未加工400600800100012000.20.40.60.8附圖3-4鋼材的表面質(zhì)量系數(shù)返回拋光磨削精車粗車未加工400600800100012000.直徑/mm配合σB/MPa4005006007008009001000120030H7/r62.252.502.753.003.253.503.754.25H7/k61.691.882.062.252.442.632.823.19H7/h61.461.631.791.952.112.282.442.7650H7/r62.753.053.363.663.964.284.605.20H7/k62.062.282.522.762.973.203.453.90H7/h61.801.982.182.382.572.783.003.40>100H7/r62.953.283.603.944.254.604.905.60H7/k62.222.462.702.963.203.463.984.20H7/h61.922.132.342.562.763.003.183.46注：⑴滾動軸承與軸配合處的值與表內(nèi)所列H7/r6配合的值相同；⑵表中無相應(yīng)的數(shù)值時，可按插入法計算。附表3-8零件與軸過盈配合處的值返回直徑/mm配合σB/MPa40050060070080090附表3－9表面高頻淬火的強化系數(shù)βq試件種類試件直徑/mmβq無應(yīng)力集中7～201.3～1.630～401.2～1.5有應(yīng)力集中7～201.6～2.830～401.5～2.5注：表中系數(shù)值用于旋轉(zhuǎn)彎曲，淬硬層厚度為0.9～1.5