After pretorsion the successor tensile yield limit and strength limit both improved very highly, but the trend of the increase of the strength limit was suspended till the pretorsional capacity reached 17, when the pretorsional capacity was greater than17 ( prestrain value was 81. 19 % of total strain ), the successor strength limit rapid failed and approached the yield limit. this illustrate the a3 steel specimen translate from plasticity into friability after pretorsion strengthen. when the specimen was operated by tension - torsion action, the yield limit had very large improved, but the strength limit changed very little. furthermore, the trend of the increase of the strength limit was suspended till the pretension capacity reached 0. 25 ( prestrain value was 66. 93 % of total strain )
A3鋼試件在
預扭轉后,后繼
拉伸屈服極限和強度極限均有很大提高,但強度極限的增大趨勢到
預扭轉量為17為止,
預扭轉量大於17 (
預應變值為總應變的81 . 19 )后強度極限迅速下降,與其屈服極限接近,這說明a3鋼試件經
預扭轉強化后逐漸由塑性轉化為脆性。該
預應變值為a3鋼試件的韌脆轉變點。 a3鋼試件在
拉伸-扭轉作用下,屈服極限有很大提高,但強度極限沒有多大改變,而且,屈服極限的增大趨勢到
預拉伸量為0 . 25應變(
預應變量為總應變量的66 . 93 )后就不再增加。
Machining deformation of aircraft monolithic component is simulated by finite element method ( fem ) and validated by experiment. the initial residual stress in pre - stretched plate is generated by simulating quenching and stretching processes. with a single tool - tooth milling process fem, the machining loads in monolithic component material removing is obtained. restart - calculation is put forward to complete the whole simulation of machining process. to verify the fem result, an experiment is carried out. the deformation distribution of the monolithic component resulting from fem shows a good agreement with the experiment result, which indicates that the key technologies presented in the paper are practicable and can be used to simulate the milling process of monolithic component to predict its deformation. lengthy and expensive trial and error experiment process can be avoided
在模擬淬火、
拉伸過程獲得含有初始殘余應力的
預拉伸板材以及模擬單齒切削過程獲得切削載荷的基礎上,提出並採用接力演算法,對一航空整體結構件的材料銑削過程進行有限元模擬,同時進行了試驗研究.結果表明,有限元模擬的整體結構件的變形與試驗具有一致性,從而證明提出的整體結構件加工模擬關鍵技術的可行性,避免了為研究加工變形而進行的繁瑣的試錯法
Using the general finite element programming package of ansys10. 0, the study of gabled frames beam - column end - plate connections is made, considering synthetically nonlinear ( material, geometry and contact ), bolt pretension forces and ratio of axial compression stress to strength. elastic - plastic finite element analyses are carried out among 28 species of 3 series under monotonic loads, in order to discuss the influence of parameters including stiffness of end - plate, bolt diameter, friction coefficients and so on
本文使用通用有限元軟體ansys10 . 0綜合考慮了三重非線性(材料非線性、幾何非線性以及狀態非線性)的影響,同時考慮了螺栓
預拉力的影響,對考慮端板厚度、端板加勁肋的設置、螺栓直徑、摩擦系數等參數不同的3個系列(端板系列,螺栓直徑系列,摩擦系數系列) 28個試件進行了有限元數值模擬,對連接節點的性能進行了分析研究。
Before plastic optical fiber widespread application, each kind of plastic optical fiber coupler must be used surely, at present the important method to manufacture the plastic optical fiber coupler is fused elongated taper. if adopt this kind of method, the conversion efficiency between the core modes and the cladding modes is low. one of the methods to solve that is
在塑料光纖廣泛應用之前必然運用到各種塑料光纖耦合器,目前熔融
拉錐法是制備塑料光纖耦合器的重要方法,然而此種方法存在纖芯模與包層模的轉換效率比較低的問題,解決這問題的一種方法是對塑料光纖進行熱
預拉錐。
The former model of staged loading and staged optimization is improved, in which the value range of pre - stress restrict in restrict equation. it provides the theoretical base for the loading time of multi - pre - stress and the value of pre - stress. and examples analyzed with linear programming and full - constrained methods prove the convergence effect well
論文在單次
預應力鋼結構的優化模型的基礎上,建立了多次
預應力鋼結構的優化模型,將原有的分級加載,分級優化的模型加以改進,在優化模型中將約束方程中的
預拉力約束的取值范圍擴大,使得多次
預應力的施加次數、施加
預拉力的數值大小的確定有了理論根據,並利用線性規劃和滿約束結合的方法進行求解,通過算例分析,收斂效果較好。
The process of rotary stretch bending without lateral compression and with lateral compression is analyzed separately, and the models of the stress distributing in the section and the springback are also presented separately to discuss the relations between pre - stretch force, lateral compression and the amount of springback. numerous experiments had been done on the equipment of ztlw - 8
本文以等邊角型材為研究對象,使用解析法分別對無側壓與側壓轉臺式
拉彎成形過程進行研究,建立了成形區截面的應力分佈模型和回彈
預測模型,從理論上探討了回彈半徑與
預拉力、側壓力的關系。
1. the measurement method of residual stress distribution in thick aluminum alloy plate is studied. aiming at the difficult problem to measure residual stress distribution in thick plate, a new method is proposed - - modified layer removal method, based on existed measurement theories and according to the characteristics of thick pre - stretched aluminum alloy plate
本文所完成的主要工作如下: 1 、鋁合金
預拉伸厚板內部殘余應力的測試方法研究針對厚板內部殘余應力測試這一技術難題,在現有測試技術研究的基礎上,結合鋁合金厚板的特點,提出了一種新的測試方法? ?改進剝層法。
Steel reinforcement bar pre - drawn platform
鋼筋預拉臺