In this study, we perform accelerated wear tests with porous journal bearings (PJBs) on a lab test rig, providing statistically reliable results under realistic operational conditions. To this end, a custom-made tribometer consisting of 5 mechanically independent but centrally controlled units was used to test five identical bearings in parallel. The test parameters were tuned to promote enough wear under mixed lubrication by increasing the clearance gap and the radial load, while minimizing the bidirectional rotational speed. A wide range of lubricant and material combinations were evaluated, the vast majority of which performed excellently (i.e., negligible wear and low friction). Only one notable combination of a low-density iron bearing paired with a standard PAO-based lubricant failed when operating at low rotational speeds, exhibiting highly unstable frictional behavior and 10–20 times the typical wear in practical applications. An analysis of Stribeck curves, recorded periodically during the wear tests as a diagnostic tool, proved that this particular combination of materials and parameters failed to run in properly, with deteriorating tribological behavior over time. A direct relation between the total wear and the maximum temperature in the tribocontact during testing helped identify this pairing as the only one operating solely under mixed lubrication (high asperity contact), explaining the excessive wear.

Graphical Abstract

中文翻译：

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确定导致多孔轴颈轴承系统故障的材料与润滑剂的配对和工作条件

在这项研究中，我们在实验室试验台上对多孔轴颈轴承（PJB）进行了加速磨损试验，从而在实际操作条件下提供了统计上可靠的结果。为此，使用了由5个机械独立但由中央控制的单元组成的定制摩擦计来并行测试5个相同的轴承。调整测试参数以增加混合间隙和径向载荷，同时使双向旋转速度最小，从而在混合润滑下促进足够的磨损。对各种各样的润滑剂和材料组合进行了评估，其中绝大多数表现出色（即，可忽略的磨损和低摩擦）。在低转速下运行时，只有低密度铁轴承与标准的PAO基润滑剂组合的一种显着失效，表现出极不稳定的摩擦性能，是实际应用中典型磨损的10–20倍。在磨损测试过程中定期记录的Stribeck曲线分析作为一种诊断工具，证明这种特殊的材料和参数组合无法正常运行，并且随着时间的推移摩擦性能会恶化。在测试过程中，摩擦接触中的总磨损与最高温度之间的直接关系有助于将这一配对确定为唯一在混合润滑（高粗糙接触）下单独运行的配对，从而解释了过度磨损。事实证明，这种特殊的材料和参数组合无法正常运行，随着时间的推移，摩擦学行为会恶化。在测试过程中，摩擦接触中的总磨损与最高温度之间的直接关系有助于将这一配对确定为唯一在混合润滑（高粗糙接触）下单独运行的配对，从而解释了过度磨损。事实证明，这种特殊的材料和参数组合无法正常运行，随着时间的推移，摩擦学行为会恶化。在测试过程中，摩擦接触中的总磨损与最高温度之间的直接关系有助于将这一配对确定为唯一在混合润滑（高粗糙接触）下单独运行的配对，从而解释了过度磨损。

图形概要