标题: 什么叫应力测试 [打印本页] 作者: wzy-007 时间: 2007-12-21 22:21 标题: 什么叫应力测试 请问什么叫应力测试作者: awen 时间: 2007-12-22 08:48
我们这里有测试配管应力,但具体不知道怎么解释 作者: caballo3157 时间: 2007-12-22 09:34
应力:当材料在外力作用下不能产生位移时,它的几何形状和尺寸将发生变化,这种形变称为应变(Strain)。材料发生形变时内部产生了大小相等但方向相反的反作用力抵抗外力,定义单位面积上的这种反作用力为应力(Sress)。按照应力和应变的方向关系,可以将应力分为正应力σ和切应力τ,正应力的方向与应变方向平行,而切应力的方向与应变垂直。按照载荷(Load)作用的形式不同,应力又可以分为拉伸压缩应力、弯曲应力和扭转应力。(------引自百度百科)/ W# q* q2 K9 [" k& q
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自然对应力的测试就叫应力测试。不同产品,不同材料,应力的测试方法和仪器各有不同。作者: Leo-Mo 时间: 2007-12-24 08:40
在标准上有没有对“应力”的定义? 作者: fasten 时间: 2007-12-24 08:53 标题: UL1598 Ver. 2.0 16.4 Mold stress relief* u* d) J6 n7 S
16.4.1 A sample of the complete thermoplastic enclosure shall be placed in a circulating air oven and: x0 N8 W7 e5 z; R2 p5 |1 N
maintained at a temperature 10 °C higher than the maximum temperature measured on the surface of the8 Z& w2 Y/ F5 u$ q
enclosure during the normal temperature test but in no case less than 70 °C, for a period of 7 h. * }; J$ ?. ?( n5 c3 u( S4 x/ L16.4.2 After the sample has cooled to room temperature, the sample shall comply with the applicable6 x: L6 Y- M) @8 X% B1 c) n$ t/ P8 O0 J
requirements of this Standard.作者: longer 时间: 2007-12-24 16:47
EN60950-1:2006 # x2 T2 R& p- V, r6 r! g! N( y4.2.7 Stress relief test: F1 Z- u( O& n4 J: W) H' X7 Y
ENCLOSURES of moulded or formed thermoplastic materials shall be so constructed that any6 k s( W8 q$ @
shrinkage or distortion of the material due to release of internal stresses caused by the% g3 N! s) L) V5 e+ n+ N4 N" @
moulding or forming operation does not result in the exposure of hazardous parts or in the0 L1 c0 S# C! K' b3 y
reduction of CLEARANCES or CREEPAGE DISTANCES below the values specified in 2.10 (or * _; {# X/ F \* W2 yAnnex G).9 p; o/ I& @) C, S
Compliance is checked by the test procedure described below or by the inspection of the 1 e9 T% p+ ?/ p, r$ j; j8 i" ~construction and the available data where appropriate. % |) s6 c8 M5 ^7 e9 Y- EOne sample consisting of the complete equipment, or of the complete ENCLOSURE together+ B( b- E3 ]" v' A# w2 @7 U. ]4 l
with any supporting framework, is placed in a circulating air oven (according to6 {" p* r# \+ ~, m
IEC 60216-4-1) at a temperature 10 K higher than the maximum temperature observed on the; L0 ?! e: r% Q2 q ~& w
ENCLOSURE during the test of 4.5.2, but not less than 70 ° C, for a period of 7 h, then permitted 9 D7 X! u# t2 F# L9 }8 `( [- j6 M, Gto cool to room temperature. / y7 k3 d# k' V1 {! ]With the concurrence of the manufacturer, it is permitted to increase the above time duration. 5 n! Z$ W9 F MFor large equipment where it is impractical to condition a complete ENCLOSURE, it is permitted 4 V6 w& K2 ?* \0 H* Q8 jto use a portion of the ENCLOSURE representative of the complete assembly with regard to 2 |( i& |, ~" P! {6 Y6 E# ithickness and shape, including any mechanical support members.1 o5 _) |6 i. ^" c2 J2 t( u# |9 I
NOTE Relative humidity need not be maintained at a specific value during this test. ! J U3 z+ |, t$ n7 i" nIf the above test is conducted, the compliance criteria of 4.2.1 apply.作者: frankzhou 时间: 2007-12-25 13:17
通俗点就是拉电源线的卡口,看是不是很耐用!!我们公司是这样测 的~作者: ferry 时间: 2008-1-12 11:09
有沒有辦法對應力進行計算? \) ]* J' I9 e2 K; T! z3 E
比如說材質不同,它的應力系數是多少等等.... ! H9 F) B9 K4 W' b N/ F4 r0 S$ W能否請一并提供此類資料,謝謝..作者: caballo3157 时间: 2008-1-12 16:50
可以查材料手册和参看材料力学等书籍作者: awen 时间: 2008-1-12 17:02
对于电源线,我们在电线和线芯上打上标记,再用156N的力拉1分钟,再根据标记的位置来确定电源线与线夹相对移动的距离和线芯与电源线外皮相对移动的距离来判断电源线有没有受到应力。作者: swk_sun 时间: 2008-4-2 23:48
搂住问得不是很准确,也就是不严禁! ! ^" V2 V7 V! G7 a在可靠性标准中应力广泛指的是:温度、湿度、振动、冲击等给产品所带来的一种影响产品功能性的环境应力。7 ]) v7 ^- t' m
不知道这样说你明白不? \7 w6 A: k+ H# v. L在针对某一产品,如电源在可靠性测试时,需要做快速稳变-40度~70度、 振动测试、机械冲击 在测试中开关机5次。在这样的条件中应力有温度应力(-40度~70度)、振动应力、冲击应力、电应力(开关机)。作者: baby28 时间: 2008-6-29 11:44
问得很简单,但是不好回答,10楼的回答我想算可以了,当然还有电应力等等!作者: jindepin 时间: 2008-7-10 16:16
可靠度應力篩選乃利用外加的環境與工作應力,使潛存於物品中製程中因較弱零組件與不良工藝等因素所造成之非設計瑕疵提早發生而曝露出來,然後利用各種適切的檢驗或測試方法,將這些帶有疵病的產品找出來予以剔除,或採取改正行動加以檢修,以便提高硬品之製造品質,維持設計時賦予之水準" x: y3 i; `1 E6 A, k/ P" Z 作者: 嘻嘻 时间: 2008-7-10 16:40
引用第9楼awenxu于2008-01-12 17:02发表的 :5 s% y$ `* b) z7 ]( F
对于电源线,我们在电线和线芯上打上标记,再用156N的力拉1分钟,再根据标记的位置来确定电源线与线夹相对移动的距离和线芯与电源线外皮相对移动的距离来判断电源线有没有受到应力。