1 Scope
This document specifies the requirements and procedures for impulse testing of hose, pipe and fitting assemblies for use in aerospace hydraulic systems.
This document applies to the impulse test of hose, pipe and fitting components for aerospace hydraulic systems. This document may also be used for component testing of other applicable aerospace fluid systems.
2 Normative references
The contents of the following documents constitute essential provisions of this document by means of normative references in the text. Where the references are dated. Only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendment sheets) applies to this document.
ISO 6771 Aerospace- Fluid systems and com- ponents- Pressure and temperature classifications
ponents- Pressure and temperature classifications)
ISO 8575 Aerospace- Fluid systems- - Hydraulic system tubing
tubing)
3 Terminology and definitions
The following terms and definitions apply to this document.
3.1 Rate of rise
Rate of rise
Defines the slope of the rise in pulse pressure (straight line section) in the pressure/time characteristic curve.
Note: The rate of rise can also be defined as the rate of change in pressure between 10% and 90% of the total rise in pulse pressure from back pressure to peak pressure.
3.2
Peak pressurepeak pressure
The maximum value of the working pressure in a short period of time.
[Source: GB/T 30206.1- 2013,2.25]
4 Test conditions.
4.1 Pulse traces
When observed on an oscilloscope, the pulse traces represent approximate pressure/time cycles. These pressure/time profiles should be within the shaded area shown in Figure 1. The dynamic pulse traces produced by the pulse test equipment should be - consistent with the pulse traces shown in Figure 1.
4.2 Calculation of lift rate
The lift rate shall be calculated according to equation (1):
n a rate of rise in kilopascals per second (kPa/s);
-peak pressure in kPa (kPa);
t2 - the time required to reach the moment 0.9p in seconds (s);
t, the time required to reach the moment of 0.1p in seconds (s).
4.3 Preparation of specimens
The preparation of the specimen should be in accordance with the relevant handling and testing requirements in the product specification.
4.4 Test fluid
The test fluid shall be the specified aerospace hydraulic system fluid or other hydraulic fluid compatible with the specimen.
5 Purpose of the test
The purpose of this test method is to determine the ability of hose, pipe and fitting assemblies to withstand hydraulic shock for qualification testing under simulated conditions.
6 Test method
To test hoses. Tube and fitting assemblies. including base or port fittings. Unless otherwise specified, peak pressures and lift rates shall be set in accordance with Table 1, peak pressures and lift rates (imperial units of measurement) are given in Table 2 and the test sequence shall be performed in accordance with Table 3.
Adjust the oscilloscope. Make sure that the peak pressure rise trace fills the oscilloscope display screen and that the pulse cycle trace is accurately recorded by photographic or other more accurate recording means, with grid lines or other markings on the photograph so that the pressure and time values at each point on the trace can be accurately checked and read. The end-to-end accuracy and sampling rate of the data acquisition system and sensor should ensure that the pulse measurement uncertainty is within the pressure waveform range of this document. The accuracy of the measurements shall be in accordance with the relevant standards.
The total number of cycles shall be 200,000 unless otherwise specified in the procurement specification.
As shown in Table 3, after the temperature has stabilised at the maximum or minimum value, a minimum holding time of 1 h is required before the start of the test sequence section. if the procurement specification requires temperature control. The fluid temperature should be measured at the test manifold. The ambient temperature test position should be approximately 150 mm from the specimen.
The peak pressure should be measured at the test manifold at the furthest end of the specimen.
7 Intended use
7.1 Standardisation
The purpose of this document is to facilitate the standardisation of impulse test requirements for hydraulic hose, pipe and fitting assemblies, standard identification and procedures and equipment for evaluating impulse tests.
7.2 Citation
If this document is cited in the specification as a requirement - part. The following additional requirements shall be specified:
a) Nominal pressure;
b) Limit working temperature;
c) specimen design.
Foreword
Introduction
1 Scope
2 Normative references
3Terms and definitions
4Test conditions
5Test purpose
6Test methods
7 Intended use
Bibliographical
1范圍
本文件規定了用于航空航天液壓系統的軟管、管道和接頭組件的脈沖試驗的要求和程序。
本文件適用于航空航天液壓系統的軟管、管道和接頭組件的脈沖試驗。本文件也可用于其他適用的航空航天流體系統的部件試驗。
2規范性引用文件
下列文件中的內容通過文中的規范性引用而構成本文件必不可少的條款。其中,注日期的引用文.件，僅該日期對應的版本適用于本文件;不注日期的引用文件,其最新版本(包括所有的修改單)適用于本文件。
ISO6771航空航天 流體系統和部件 壓 力和溫度分類( Aerospace- Fluid systems and com-
ponents- Pressure and temperature classifications)
ISO 8575航空航天流體系統液 壓系統管路( Aerospace- Fluid systems- - Hydraulic system
tubing)
3術語和定義
下列術語和定義適用于本文件。
3.1
升率rate of rise
定義壓力/時間特性曲線中,脈沖壓力上升部分(直線段)的斜率。
注:升率也可定義為脈沖壓力從背壓升高到峰值壓力的總上升量的10%~90%之間的壓力變化率。
3.2
峰值壓力peak pressure
短時間內工作壓力的最大值。
[來源:GB/T 30206.1- 2013,2.25]
4試驗條件.
4.1脈沖跡線
在示波器上觀察時,脈沖跡線代表了近似的壓力/時間循環。這些壓力/時間曲線應在圖1所示的陰影區域范圍內。脈沖試驗設備產生的動態脈沖跡線應與圖1所示的脈沖跡線--致。
4.2升率的計算
升率應按公式(1)計算:
n一升率,單位為千帕每秒(kPa/s);
-峰值壓力,單位為千帕(kPa);
t2-一達到0.9p的時刻所需的時間,單位為秒(s);
t，一達到0.1p的時刻所需的時間,單位為秒(s)。
4.3試樣的制 備
試樣的制備應符合產品規范中相關的處理和測試要求。
4.4試驗 流體
試驗流體應是指定的航空航天液壓系統流體或與試樣相容的其他液壓油。
5試驗目的
本試驗方法旨在確定軟管、管道和接頭組件承受液壓沖擊的能力，以便在模擬條件下進行鑒定試驗。
6試驗方法
為測試軟管.管道和接頭組件.包括底座或端口接頭.循環速率應為(70士5)次/min。除非另有規定,峰值壓力和升率應按表1設定,表2給出了峰值壓力和升率(英制計量單位),試驗順序應按表3執行。
調整示波器.使峰值壓力上升跡線能占滿示波器顯示屏幕,采用照相或其他精度更高的記錄手段準確記錄脈沖循環跡線,照片上應有格柵線或其他標志,以便能準確地檢查和讀出跡線上各點的壓力值和時間值。數據采集系統和傳感器的端到端精度和采樣率應確保脈沖測量不確定度在本文件的壓力波形范圍內。測量的準確性應符合相關標準。
除非采購規范另有規定,循環總數應為20萬次。
如表3所示，當溫度穩定在最大值或最小值后，在試驗序列部分開始之前至少需要保溫1 h。如果采購規范要求溫度控制.則應在試驗歧管處測量流體溫度。環境溫度試驗位置應距離試樣約150mm。
應:在試樣最遠端試驗歧管處測量峰值壓力。
7預期用途
7.1標準化
本文件旨在促進液壓軟管、管道和接頭組件的脈沖試驗要求、標準鑒定和評估脈沖試驗的程序和設備的標準化。
7.2引用
如:果在規范中引用本文件作為要求的--部分.則應指定以下附加要求:
a) 名義壓力;
b) 極限工作溫度;
c) 試樣設計。
