3890689049

Snhmitted: 2014-12-12 Reeised: 2015-04-22 Accepted: 2015-04-22

Online: 2015-08-28

Solid State Phenomena ISSN: 1662-9779. Vol. 240. pp 161-167 doi:!0.4028/www.scientific.net/SSPJ40.161 & 2016 Trans Tech Pnhlications. Switzerland

EFFECT OF A NOTCH ON IMPACT RESISTANCE OF THE EPIDIAN 57/Z1 EPOXY MATERIAŁ AFTER "THERMAL SHOCK"

KłONICA Mariusz¹, KUCZMASZEWSKI Józef², SAMBORSKI Sylwester³

'Lublin University of Technology, 36 Nadbystrzycka St., 20-618 Lublin, Poland, [phone],

[e-mail]

²Lublin University of Technology, 36 Nadbystrzycka St., 20-618 Lublin, Poland, [phone],

[e-mail]

³Lublin University of Technology, 36 Nadbystrzycka St., 20-618 Lublin, Poland, [phone],

[e-mail]

Abstract

Adhcsivc bonding is incrcasingly bcing applicd as structural joining tcchniquc in highly rcliablc machincs and applianccs opcrating in thc circumstanccs of variablc thcrmomcchanical loads.

The manufacturcd spccimcns of thc Epidian 57/Z-l cpoxy materia! had been subjected to cyc lic thcrmal loading, with rcspcct to a defined program, in a thcrmal shock chambcr within a temperaturę rangę of -40°C to +60°C for 200 cyclcs. The accepted temperaturę rangę was typical for machincry maintcnance, including thc aireraft.

The aim of thc rcscarch was first of all determination of thcrmal load (fatiguc), as well as thc prcscncc of notch cffcct on thc rcsistancc to fracturc.

A significant measure of thc adhesivc bonds quality Ls thc repeatability of thc strength examination rcsults, both in thc summary and long lasting tests. It is oficn morę important critcrion for thc adhesivc joint selection than higher strength of thc joints using thc partie ular adhesive.

The obtained rcsults of thc conductcd rcsearch havc been elaborated statistically with rcspcct to thc appropriatc scicntific standards.

1. Introduction

The cffcct of cyclic thcrmal loading on thc summary and long lasting strength, both static and dynamie Ls rclativcly poorly rccognizcd, cspccially in thc aspcct of thc mcchanochcmical changcs taking place within thc tcxturc of thc adhcsivc joint [1,2, 11J. In numerous papers it was provcd, that thc thcrmal treatment of thc joints in thc stage of curing hasa significant cffcct on their physical propcrtics. It is conncctcd to thc so-callcd phenomenon of thc wcld after-bake, which leads to an incrcasc of thc dcgrcc of adhcsivc materia! crosslinking. This incrcasc most often induccs growth of thc longitudinal and traasvcrsal cocfficicnt of clasticity. Usually it is advantageous from thc point of vicw of thc joints cxploitation at clcvatcd temperaturę. Howcvcr, thcrc is a risk of advcr.sc changcs in impact rcsistancc, which is an important parameter, as it contributc to conclusions on thc adhcsivc joint usability in terms of dynamie loads.

In typical thcrmal circumstanccs of thc Earth climatc, for cxamplc in maintcnance of aireraft, thc airłicld temperaturę may lead to hcating of an acroplanc load-bcaring clcmcnts abovc 60°C, whcrcas after thc takcoff it quickly dccrcascs to ca. -40 °C. It is thus a thcrmal shock at thc ncuralgic moment offlight.

For thc purposc of thc possibly most surc prcdiction of thc adhesivc joints strength in terms of changeablc thcrmomcchanical loads thc knowledge on thc adhesivc joint „rcaction” to shock changcs of thc maintcnance temperaturę [7J. Thcrmal fatiguc of thc adhcsivc joint in curcd State may imply aging proccsscs, incrcasc thc polydispcrsity of thc materiał and so altcr thc mcchanical propcrtics. Impact rcsistancc can be a good estimator of such changcs, as it can allow for both thc cftccts of after-bake at thc stage of thc joint constitution, as well as thc changcs rcsulting from thcrmal fatiguc.

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