International Scientific Conference PRO-TECH-MA ’16

PROGRESSIVE TECHNOLOGIES AND MATERIALS

P

THE LOAD CAPACITY RESEARCH OF THE CLINCH-ADHESIVE JOINTS SUBJECTED TO BIAXIAL TENSION

Andrzej KUBIT[1], Jacek MUCHA2, Waldemar WITKOWSKI3

There are many opportunities to influence the lightness of the sheet metal products. Obviously, appropriate design concept with appropriate selected sheet material may lead to fulfill this purpose. Additional and important issues are the joining technologies used in the assembly process of thin-walled structures.

Certain mechanical properties of the joint may be obtained by applying the mechanical properties of conventional joints. During the assembly process of sheet metal parts, an additional of sealing or adhesive-sealing layers between sheets are often used with conventional joining methods like resistance spot welding or other bonding technologies, as a supporting technique to increase the strength of joints. In less responsible elements of thin-walled structures, more often the plastically formed joint like clinching are more often used. A prerequisite for fast positioning in manufacturing process is that the parts to be joined does not require previously cut holes. During the clinching with adhesive joining process, the clinching joint can be an assembly stabilizer until the adhesive reach the final properties. For this type of clinch-bonded joints the ensure of appropriate adhesive layer thickness until solidify is a problem.

Hybrid joints – clinching and adhesive – have a better resistance to moisture penetration than the standard clinching joints. Adhesives and sealants used in joining of thin-walled structures increase the tightness and corrosion resistance in the sheets contact area. The greatest advantage is that the stiffness of the construction increases. The adhesive layer also increases the damping of vibrations.

In this paper, the results of experimental research of the clinching, bonded and clinch-bonded joints strength were presented. The strength tests were carried out for the biaxial tension of joint samples. The modeling of experimental behaviors of hybrid joints according to primary load direction was realized for H-shaped samples using a specially designed apparatus (Fig. 1).The joint strength structure was determined with accordance to the ISO 12996 standard.

Fig. 1. Joint samples in special apparatus during the strength test

The maximumload-carryingpossibilities, forcing thejoint embossmentdeformation, dependingonloaddirectionwererealizedfortheangle from00 to 900 at 150. Plateswithpinholes,whichdetermined theloadangle,wereconnectedtomachineholdersby twopins (Fig. 2).

Fig. 2. Joint load conditions in a practical strength test (load specifications and loading angles)

The normal force (Ft) and shear force (Fs) can beidentified:

Ft(α)=Fy·sinα

Fs(α)=Fx·cosα

Their values are changing, depending on the sample angle of inclination α in apparatus, satisfying the equation of joint fracturecriterion in each position:

where:α the angle of the load,Ft(α) is the normal load depending on the angle α, Fs(α) the shear load depending on the angle α,Ftmax the maximum normal load during tearing test, Fsmax the maximum shear load during shearing test, anda and b the coefficients of the separation function model curves.

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[1] , 2 , , Rzeszow University of Technology, Poland