概念
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
紐馬克-法是一種將線性加速度方法普遍化的方法。紐馬克-法可認為是概括了平均常加速度和線性加速度算法的一種廣義算法。紐馬克-法有擬靜力增量方程形式和不同類型的擬靜力全量方程形式。在有限元動態分析中最常用的有中心差分法、紐馬克-法(Newmark)和威爾遜-θ法。
基本原理
![紐馬克-β法](/img/4/505/nBnauM3XxMjM1UzMzkDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL5AzL0AzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/8/485/nBnauM3X3AzM1UzMyEDMyADN0UTMyITNykTO0EDMwAjMwUzLxAzL3UzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
紐馬克法是對線性加速度假定做了修正,在 時刻的速度和位移表達式中引入兩個參數 、 ,得紐馬克法的兩個基本方程:
![紐馬克-β法](/img/d/4af/nBnauM3X0UTN3gTN0ADN3QTN1UTM1QDN5MjM5ADMwAjMwUzLwQzL2MzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/4/4a2/nBnauM3X0YjM4gzMzEzM3QTN1UTM1QDN5MjM5ADMwAjMwUzLxMzL1czLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/2/071/nBnauM3XycjMyETMzITM3QTN1UTM1QDN5MjM5ADMwAjMwUzLyEzL3AzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/e/de3/nBnauM3X1cDO2YDOxkzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL5MzLxUzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/6/585/nBnauM3X0YTM2cjNxYDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL2AzLxMzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/a/d73/nBnauM3X0MTM4EDMwgTM3QTN1UTM1QDN5MjM5ADMwAjMwUzL4EzL4UzLt92YucmbvRWdo5Cd0FmLxE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/6/585/nBnauM3X0YTM2cjNxYDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL2AzLxMzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/8/951/nBnauM3X2gjN0MDO0cDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL3AzLwUzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/b35/nBnauM3X2IDO5YzM0ITMzEzM1UTM1QDN5MjM5ADMwAjMwUzLyEzLygzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/33b/nBnauM3X3gzNzYTO1cjN1IDN0UTMyITNykTO0EDMwAjMwUzL3YzL2YzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/7da/nBnauM3X2IjNwYjM3UTN0YzM1UTM1QDN5MjM5ADMwAjMwUzL1UzLzMzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/6/585/nBnauM3X0YTM2cjNxYDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL2AzLxMzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/d/3eb/nBnauM3XxQTM0UTO5gzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL4MzL2gzLt92YucmbvRWdo5Cd0FmLxE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/b35/nBnauM3X2IDO5YzM0ITMzEzM1UTM1QDN5MjM5ADMwAjMwUzLyEzLygzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/b35/nBnauM3X2IDO5YzM0ITMzEzM1UTM1QDN5MjM5ADMwAjMwUzLyEzLygzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
若在 和 兩個式子中令 ,只保留參數 ,即為紐馬克- 法。 值常取為 ;令 , ,這就相當於加速度在 時段內線性變化,即威爾遜- 法中 的情況;若令 , ,這相當於加速度在 內為常量,其值為 兩端加速度的平均值,即為平均加速度法。
![紐馬克-β法](/img/2/071/nBnauM3XycjMyETMzITM3QTN1UTM1QDN5MjM5ADMwAjMwUzLyEzL3AzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/e/de3/nBnauM3X1cDO2YDOxkzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL5MzLxUzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
由 和 兩個式子,可得:
![紐馬克-β法](/img/7/9e5/nBnauM3XyEzM4YDO4gDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL4AzL2gzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/7/abe/nBnauM3X0cTOzgTO3cjM3QTN1UTM1QDN5MjM5ADMwAjMwUzL3IzLxIzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/4/505/nBnauM3XxMjM1UzMzkDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL5AzL0AzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
將上面兩個式子代入 時刻的動力方程,經整理後得:
![紐馬克-β法](/img/5/d85/nBnauM3XxMDO5AzN2EzM3QTN1UTM1QDN5MjM5ADMwAjMwUzLxMzLwMzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
式中
![紐馬克-β法](/img/7/c85/nBnauM3X2QTM1kTNwQzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL0MzLwYzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/7/0a5/nBnauM3X2QTO2ATN2gzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL4MzLwMzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/b35/nBnauM3X2IDO5YzM0ITMzEzM1UTM1QDN5MjM5ADMwAjMwUzLyEzLygzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/b35/nBnauM3X2IDO5YzM0ITMzEzM1UTM1QDN5MjM5ADMwAjMwUzLyEzLygzLt92YucmbvRWdo5Cd0FmLyE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/1/c4c/nBnauM3XxATMyQTM1UjM3QTN1UTM1QDN5MjM5ADMwAjMwUzL1IzLwczLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/8/cc4/nBnauM3X2UDM3IjM5EjM3QTN1UTM1QDN5MjM5ADMwAjMwUzLxIzL3UzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/b68/nBnauM3XwMjN2czN5YjN5ADN0UTMyITNykTO0EDMwAjMwUzL2YzL0IzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/0f5/nBnauM3X1QzN3gzMzkDM3QTN1UTM1QDN5MjM5ADMwAjMwUzL5AzL4IzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/f/726/nBnauM3X0ITM4UzMzQDO2UzM1UTM1QDN5MjM5ADMwAjMwUzL0gzLzgzLt92YucmbvRWdo5Cd0FmL0E2LvoDc0RHa.jpg)
![紐馬克-β法](/img/8/49f/nBnauM3X2MzM2QTO0YjM0IDN0UTMyITNykTO0EDMwAjMwUzL2IzL0YzLt92YucmbvRWdo5Cd0FmLxE2LvoDc0RHa.jpg)
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![紐馬克-β法](/img/f/8ad/nBnauM3XzQDN3UDO2UzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL1MzLzUzLt92YucmbvRWdo5Cd0FmLxE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/1/920/nBnauM3XxcDO1cDO2gzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL4MzL3gzLt92YucmbvRWdo5Cd0FmLwE2LvoDc0RHa.jpg)
![紐馬克-β法](/img/0/2da/nBnauM3XxQjM4EjMzYzM3QTN1UTM1QDN5MjM5ADMwAjMwUzL2MzL3MzLt92YucmbvRWdo5Cd0FmLzE2LvoDc0RHa.jpg)
紐馬克-法的計算精度取決於時間步長的大小。而時間步長的確定必須考慮荷載變化情況和系統自振周期的長短。為了保證感興趣的高頻分量的貢獻,通常要求小於對回響有重要影響的最小結構自振周期的。穩定性研究還表明:當時,紐馬克-法是無條件穩定的;時,則是有條件穩定的,其穩定性條件為:對於,和這三種情況,必須分別小於,和,其中為結構的最小自振周期。