We study the stellar morphological evolution of disk galaxies within clusters in the TNG50 and TNG100 runs from the IllustrisTNG simulation suite .
We select satellites of masses 10 ^ { 9.7 } \leq M _ { *,z = 0 } / { M } _ { \sun } \leq 10 ^ { 11.6 } residing in clusters of total masses 10 ^ { 14 } \lesssim M _ { \text { 200 c,z = 0 } } / { M } _ { \sun } \leq 10 ^ { 14.6 } at z = 0 and study those that were disks at accretion according to a kinematic morphology indicator ( the circularity fraction ) .
The galaxies ’ histories are traced from the time of accretion to z = 0 and compared to a control sample of central galaxies mass-matched at the time of accretion .

Most cluster disks become non-disky by z = 0 , in stark contrast with the control disks , of which a significant fraction remains disky over the same timescales .
The transformation to non-disky morphologies is accompanied by gas removal and star formation quenching for both cluster and control galaxies .
However , cluster disks that become non-disky by z = 0 have lost dark matter ( DM ) mass and show little growth or a loss of stellar mass , whereas the corresponding control disks show significant growth in both components .
Most cluster satellites change their morphologies on similar timescales regardless of stellar mass , in \sim 0.5 - 4 billion years after accretion .
Cluster disks that have had more numerous and closer pericentric passages show the largest change in morphology .
Morphological change in both cluster and control disks requires the presence of a gravitational perturbation to drive stellar orbits to non-disky configurations , along with gas removal/heating to prevent replenishment of the disk through continued star-formation .
For cluster disks , the perturbation is in the form of impulsive tidal shocking at pericentres and not tidal stripping of the outer disk stellar material , whereas for control disks , a combination of mergers and AGN feedback appears to be the key driving force behind morphological transformations .